ADSP-218x DSP Instruction Set Reference (Rev. 2.0)

ADSP-218x DSP
Instruction Set Reference
Revision 2.0, November 2004
Part Number
82-002000-01
Analog Devices, Inc.
One Technology Way
Norwood, Mass. 02062-9106
a
Copyright Information
©2004 Analog Devices, Inc., ALL RIGHTS RESERVED. This document
may not be reproduced in any form without prior, express written consent
from Analog Devices, Inc.
Printed in the USA.
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The Analog Devices logo, EZ-ICE, and VisualDSP++ are registered trademarks of Analog Devices, Inc.
All other brand and product names are trademarks or service marks of
their respective owners.
CONTENTS
INTRODUCTION
Audience ...................................................................................... 1-1
Contents Overview ....................................................................... 1-2
Development Tools ....................................................................... 1-4
Additional Product Information .................................................... 1-7
For Technical or Customer Support ............................................... 1-7
What’s New in This Manual .......................................................... 1-8
Related Documents ....................................................................... 1-8
Conventions ................................................................................. 1-8
PROGRAMMING MODEL
Overview ...................................................................................... 2-1
Data Address Generators .......................................................... 2-2
Always Initialize L Registers ................................................ 2-4
Program Sequencer .................................................................. 2-4
Interrupts ........................................................................... 2-5
Loop Counts ....................................................................... 2-5
Status and Mode Bits .......................................................... 2-6
Stacks ................................................................................. 2-6
ADSP-218x DSP Instruction Set Reference
iii
CONTENTS
Computational Units .............................................................. 2-7
Bus Exchange .......................................................................... 2-8
Timer ..................................................................................... 2-8
Serial Ports .............................................................................. 2-8
Memory Interface and SPORT Enables ................................... 2-9
Program Example ....................................................................... 2-10
Example Program: Setup Routine Discussion ......................... 2-13
Example Program: Interrupt Routine Discussion .................... 2-15
Hardware Overlays and Software Issues ....................................... 2-16
Libraries and Overlays ........................................................... 2-17
Interrupts and Overlays ......................................................... 2-17
Loop Hardware and Overlays ................................................ 2-19
SOFTWARE EXAMPLES
Overview ...................................................................................... 3-1
System Development Process ....................................................... 3-3
Single-Precision Fir Transversal Filter ............................................ 3-5
Cascaded Biquad IIR Filter ........................................................... 3-7
Sine Approximation ...................................................................... 3-9
Single-Precision Matrix Multiply ................................................. 3-11
Radix-2 Decimation-in-Time FFT .............................................. 3-13
Main Module ........................................................................ 3-14
DIT FFT Subroutine ............................................................ 3-16
Bit-Reverse Subroutine .......................................................... 3-21
Block Floating-Point Scaling Subroutine ................................ 3-22
iv
ADSP-218x DSP Instruction Set Reference
CONTENTS
INSTRUCTION SET
Quick List Of Instructions ............................................................ 4-2
Instruction Set Overview ............................................................... 4-5
Multifunction Instructions ............................................................ 4-7
ALU/MAC With Data and Program Memory Read .................. 4-7
Data and Program Memory Read ............................................. 4-9
Computation With Memory Read ........................................... 4-9
Computation With Memory Write ........................................ 4-10
Computation With Data Register Move ................................. 4-10
ALU, MAC and Shifter Instructions ............................................ 4-14
ALU Group ........................................................................... 4-14
MAC Group .......................................................................... 4-16
Shifter Group ........................................................................ 4-18
MOVE: Read and Write Instructions ........................................... 4-20
Program Flow Control ................................................................ 4-22
Miscellaneous Instructions .......................................................... 4-25
Extra Cycle Conditions ............................................................... 4-27
Multiple Off-Chip Memory Accesses ...................................... 4-27
Wait States ............................................................................ 4-27
SPORT Autobuffering and DMA ........................................... 4-28
Instruction Set Syntax ................................................................. 4-28
Punctuation and Multifunction Instructions ........................... 4-28
Syntax Notation Example ...................................................... 4-29
Status Register Notation ........................................................ 4-30
ADSP-218x DSP Instruction Set Reference
v
CONTENTS
ALU Instructions ........................................................................ 4-31
Add/Add With Carry ............................................................ 4-32
Subtract X-Y/Subtract X-Y With Borrow ............................... 4-35
Subtract Y-X/Subtract Y-X With Borrow ................................ 4-39
Bitwise Logic: AND, OR, XOR ............................................. 4-42
Bit Manipulation: TSTBIT, SETBIT, CLRBIT, TGLBIT ....... 4-45
Clear: PASS .......................................................................... 4-48
Negate .................................................................................. 4-52
NOT .................................................................................... 4-54
Absolute Value: ABS ............................................................. 4-56
Increment ............................................................................. 4-59
Decrement ............................................................................ 4-61
Divide Primitives: DIVS and DIVQ ...................................... 4-63
Generate ALU Status Only: NONE ....................................... 4-71
MAC Instructions ...................................................................... 4-73
Multiply ............................................................................... 4-74
Multiply With Cumulative Add ............................................. 4-78
Multiply With Cumulative Subtract ...................................... 4-82
Squaring ............................................................................... 4-86
MAC Clear ........................................................................... 4-90
MAC Transfer MR ................................................................ 4-92
Conditional MR Saturation ................................................... 4-94
vi
ADSP-218x DSP Instruction Set Reference
CONTENTS
Shifter Instructions ..................................................................... 4-96
Arithmetic Shift .................................................................... 4-97
Logical Shift ........................................................................ 4-100
Normalize ........................................................................... 4-103
Derive Exponent ................................................................. 4-106
Block Exponent Adjust ........................................................ 4-110
Arithmetic Shift Immediate ................................................. 4-112
Logical Shift Immediate ....................................................... 4-114
Move Instructions ..................................................................... 4-116
Register Move ..................................................................... 4-117
Load Register Immediate ..................................................... 4-119
Data Memory Read (Direct Address) .................................... 4-122
Data Memory Read (Indirect Address) ................................. 4-124
Program Memory Read (Indirect Address) ............................ 4-126
Data Memory Write (Direct Address) ................................... 4-128
Data Memory Write (Indirect Address) ................................ 4-130
Program Memory Write (Indirect Address) ........................... 4-133
IO Space Read/Write ........................................................... 4-135
Program Flow Instructions ........................................................ 4-137
JUMP ................................................................................. 4-138
CALL .................................................................................. 4-140
JUMP or CALL on Flag In Pin ............................................ 4-142
Modify Flag Out Pin ........................................................... 4-144
RTS (Return from Subroutine) ............................................ 4-146
ADSP-218x DSP Instruction Set Reference
vii
CONTENTS
RTI (Return from Interrupt) ............................................... 4-148
Do Until ............................................................................. 4-150
Idle ..................................................................................... 4-153
MISC Instructions .................................................................... 4-155
Stack Control ...................................................................... 4-156
TOPPCSTACK .................................................................. 4-159
Mode Control ..................................................................... 4-162
Interrupt Enable and Disable ............................................... 4-165
Program Memory Overlay Register Update .......................... 4-166
Data Memory Overlay Register Update ................................ 4-169
Modify Address Register ...................................................... 4-172
No Operation ..................................................................... 4-174
Multifunction Instructions ........................................................ 4-175
Computation With Memory Read ....................................... 4-176
Computation With Register-to-Register Move ..................... 4-182
Computation With Memory Write ...................................... 4-187
Data and Program Memory Read ......................................... 4-192
ALU/MAC With Data and Program Memory Read .............. 4-194
viii
ADSP-218x DSP Instruction Set Reference
CONTENTS
INSTRUCTION CODING
Opcode Definitions ..................................................................... A-2
Opcode Mnemonics ..................................................................... A-9
AMF ALU / MAC Function Codes ......................................... A-9
BO ....................................................................................... A-10
CC ....................................................................................... A-10
COND Status Condition Codes ........................................... A-11
CP Counter Stack Pop Codes ................................................ A-11
D Direction Codes ............................................................... A-12
DD Double Data Fetch Data Memory
Destination Codes ............................................................. A-12
DREG Data Register Codes .................................................. A-12
DV Divisor Codes for Slow Idle Instruction (IDLE (n)) ........ A-14
FIC FI Condition Codes ...................................................... A-14
FO Control Codes for Flag Output Pins
(FO, FL0, FL1, FL2) ......................................................... A-14
G Data Address Generator Codes .......................................... A-15
I Index Register Codes .......................................................... A-15
LP Loop Stack Pop Codes .................................................... A-15
M Modify Register Codes ..................................................... A-16
PD Dual Data Fetch Program Memory
Destination Codes ............................................................. A-16
PP PC Stack Pop Codes ........................................................ A-16
REG Register Codes ............................................................. A-17
S Jump/Call Codes ............................................................... A-18
ADSP-218x DSP Instruction Set Reference
ix
CONTENTS
SF Shifter Function Codes .................................................... A-18
SPP Status Stack Push/Pop Codes .......................................... A-19
T Return Type Codes ............................................................ A-19
TERM Termination Codes for DO UNTIL ........................... A-20
X X Operand Codes .............................................................. A-21
Y Y Operand Codes .............................................................. A-21
YY ........................................................................................ A-21
Z ALU/MAC Result Register Codes ...................................... A-22
YY, CC, BO ALU / MAC Constant Codes (Type 9) ............... A-22
INDEX
x
ADSP-218x DSP Instruction Set Reference
1 INTRODUCTION
The ADSP-218x DSP Instruction Set Reference provides assembly syntax
information for the ADSP-218x Digital Signal Processor (DSP). The syntax descriptions for instructions that execute within the DSP’s processor
core include processing elements, program sequencer, and data address
generators. For architecture and design information on the DSP, see the
ADSP-218x DSP Hardware Reference.
Audience
DSP system designers and programmers who are familiar with signal processing concepts are the primary audience for this manual. This manual
assumes that the audience has a working knowledge of microcomputer
technology and DSP-related mathematics.
DSP system designers and programmers who are unfamiliar with signal
processing can use this manual, but should supplement this manual with
other texts, describing DSP techniques.
All readers, particularly programmers, should refer to the DSP’s development tools documentation for software development information. For
additional suggested reading, see the section “Additional Product Information” on page 1-7.
ADSP-218x DSP Instruction Set Reference
1-1
Contents Overview
Contents Overview
The Instruction Set Reference is a four-chapter book that describes the
instructions syntax for the ADSP-218x DSPs.
Chapter 1, “Introduction”, provides introductory information including
contacts at Analog Devices, an overview of the development tools, related
documentation and conventions.
Chapter 2, “Programming Model”, describes the computational units of
the ADSP-218x DSPs and provides a programming example with
discussion.
Chapter 3, “Software Examples”, describes the process to create executable
programs for the ADSP-218x DSPs. It provides several software examples
that can be used to create programs.
Chapter 4, “Instruction Set”, presents information organized by the type
of instruction. Instruction types relate to the machine language opcode
for the instruction. On this DSP, the opcodes categorize the instructions
by the portions of the DSP architecture that execute the instructions.
Appendix A, “Instruction Coding”, provides a summary of the complete
instruction set of the ADSP-218x DSPs with opcode descriptions.
Each reference page for an instruction shows the syntax of the instruction,
describes its function, gives one or two assembly-language examples, and
identifies fields of its opcode. The instructions are also referred to by type,
ranging from 1 to 31. These types correspond to the opcodes that
ADSP-218x DSPs recognize, but are for reference only and have no bearing on programming.
Some instructions have more than one syntactical form; for example,
instruction “Multiply” on page 4-73 has many distinct forms.
1-2
ADSP-218x DSP Instruction Set Reference
Introduction
Many instructions can be conditional. These instructions are prefaced by
IF cond; for example:
IF EQ MR = MX0 * MY0 (SS);
In a conditional instruction, the execution of the entire instruction is
based on the condition.
The following instructions groups are available for ADSP-218x DSPs:
• “Quick List Of Instructions” on page 4-2—This section provides a
a quick reference to all instructions.
• “ALU Instructions” on page 4-31—These instruction specify operations that occur in the DSP’s ALU.
• “MAC Instructions” on page 4-72—These instructions specify
operations that occur in the DSP’s Multiply–Accumulator.
• “Shifter Instructions” on page 4-94—These instructions specify
operations that occur in the DSP’s Shifter.
• “Move Instructions” on page 4-113—These instructions specify
memory and register access operations.
• “Program Flow Instructions” on page 4-133—These instructions
specify program sequencer operations.
• “MISC Instructions” on page 4-151—These instructions specify
memory access operations.
• “Multifunction Instructions” on page 4-171—These instructions
specify parallel, single-cycle operations.
Appendix A, “Instruction Coding”, lists the instruction encoding fields by
type number and defines opcode mnemonics as listed alphabetically.
ADSP-218x DSP Instruction Set Reference
1-3
Development Tools
Development Tools
The ADSP-218x DSPs are supported by VisualDSP++®, an easy-to-use
programming environment, comprised of a VisualDSP++ Integrated
Development and Debugging Environment (IDDE). VisualDSP++ lets
you manage projects from start to finish from within a single, integrated
interface. Because the project development and debug environments are
integrated, you can move easily between editing, building, and debugging
activities.
Flexible Project Management. VisualDSP++ IDDE provides flexible
project management for the development of DSP applications. VisualDSP++ includes access to all the activities necessary to create and debug
DSP projects. You can create or modify source files or view listing or map
files with the IDDE Editor. This powerful Editor is part of VisualDSP++
and includes multiple language syntax highlighting, OLE drag and drop,
bookmarks, and standard editing operations such as undo/redo,
find/replace, copy/paste/cut, and goto.
Also, VisualDSP++ includes access to the C Compiler, C Runtime
Library, Assembler, Linker, Loader, Simulator, and Splitter tools You
specify options for these tools through property dialog boxes. Tool dialog
boxes are easy to use, and make configuring, changing, and managing your
projects simple. These options control how the tools process inputs and
generate outputs, and have a one-to-one correspondence to the tools’
command line switches. You can define these options once, or modify
them to meet changing development needs. You can also access the tools
from the operating system command line if you choose.
Greatly Reduced Debugging Time. The Debugger has an easy-to-use,
common interface for all processor simulators and emulators available
through Analog Devices and third parties or custom developments. The
Debugger has many features that greatly reduce debugging time. You can
view C source interspersed with the resulting Assembly code. You can profile execution of a range of instructions in a program; set simulated watch
1-4
ADSP-218x DSP Instruction Set Reference
Introduction
points on hardware and software registers, program and data memory; and
trace instruction execution and memory accesses. These features enable
you to correct coding errors, identify bottlenecks, and examine DSP performance. You can use the custom register option to select any
combination of registers to view in a single window. The Debugger can
also generate inputs, outputs, and interrupts so you can simulate real
world application conditions.
Software Development Tools. The Software Development Tools, which
support the ADSP-218x DSPs, allow you to develop applications that take
full advantage of the DSP architecture, including shared memory and
memory overlays. Software Development tools include C Compiler, C
Runtime Library, DSP and Math Libraries, Assembler, Linker, Loader,
Simulator, and Splitter.
C Compiler and Assembler. The C Compiler generates efficient code that
is optimized for both code density and execution time. The C Compiler
allows you to include Assembly language statements inline. Because of
this, you can program in C and still use Assembly for time-critical loops.
You can also use pretested Math, DSP, and C Runtime Library routines to
help shorten your time to market. The ADSP-218x Assembly language is
based on an algebraic syntax that is easy to learn, program, and debug.
The add instruction, for example, is written in the same manner as the
actual equation using registers for variables (for example, AR = AX0 +
AY0;).
Linker and Loader. The Linker provides flexible system definition
through Linker Description Files (.LDF). In a single .LDF file, you can
define different types of executables for a single or multiprocessor system.
The Linker resolves symbols over multiple executables, maximizes memory use, and easily shares common code among multiple processors. The
Loader supports creation of a 16-bit host port and 8-bit PROM boot
images. Along with the Linker, the Loader allows a variety of system configurations with smaller code and faster boot time.
ADSP-218x DSP Instruction Set Reference
1-5
Development Tools
Simulator. The Simulator is a cycle-accurate, instruction-level simulator
that allows you to simulate your application in real time.
Emulator. The EZ-ICE® serial emulator system provides state-of-the-art
emulation for the ADSP-218x DSPs using a controlled environment for
observing, debugging, and testing activities in a target system. The key
features of the ADSP-218x EZ-ICE include a shielded enclosure with the
reset switch, a high speed RS-232 serial port interface, and support for
2.5, 3.3 and 5.0V DSPs. The EZ-ICE connects directly to the target processor via the emulation interface port. It’s ease of use, full speed
emulation, and shield board ensures that your design process runs
smoothly.
3rd Party Extensible. The VisualDSP++ environment enables third party
companies to add value using Analog Devices’ published set of Application Programming Interfaces (API). Third party products including
runtime operating systems, emulators, high-level language compilers, multiprocessor hardware can interface seamlessly with VisualDSP++ thereby
simplifying the tools integration task. VisualDSP++ follows the COM API
format. Two API tools, Target Wizard and API Tester, are also available
for use with the API set. These tools help speed the time-to-market for
vendor products. Target Wizard builds the programming shell based on
API features the vendor requires. The API tester exercises the individual
features independently of VisualDSP++. Third parties can use a subset of
these APIs that meets their application needs. The interfaces are fully supported and backward compatible.
Further details and ordering information are available in the VisualDSP++
Development Tools data sheet. This data sheet can be requested from any
Analog Devices sales office or distributor.
1-6
ADSP-218x DSP Instruction Set Reference
Introduction
Additional Product Information
Analog Devices can be found on the internet at http://www.analog.com.
Our Web pages provide information about the company and products,
including access to technical information and documentation, product
overviews, and product announcements.
You may obtain additional information about Analog Devices and its
products in any of the following ways:
Visit our World Wide Web site at www.analog.com
• FAX questions or requests for information to 1(781)461-3010.
• Access the division’s File Transfer Protocol (FTP) site at ftp
ftp.analog.com or ftp 137.71.23.21 or ftp://ftp.analog.com.
For Technical or Customer Support
You can reach our Customer Support group in the following ways:
• E-mail questions to:
dsp.support@analog.com, dsptools.support@analog.com
dsp.europe@analog.com
or
(European customer support)
• Contact your local ADI sales office or an authorized ADI
distributor
• Send questions by mail to:
Analog Devices, Inc.
One Technology Way
P.O. Box 9106
Norwood, MA 02062-9106
USA
ADSP-218x DSP Instruction Set Reference
1-7
What’s New in This Manual
What’s New in This Manual
This edition of the ADSP-218x DSP Instruction Set Reference is formatted
for easy reading and conversion to online help. Some technical information is also updated or corrected.
Related Documents
For more information about Analog Devices DSPs and development
products, see the following documents:
• ADSP-218x DSP Hardware Reference
• VisualDSP++ Getting Started Guide for ADSP-218x DSPs
• VisualDSP++ User's Guide for ADSP-218x DSPs
• VisualDSP++ C Compiler & Library Manual for ADSP-218x DSPs
• VisualDSP++ Assembler Manual for ADSP-218x DSPs
• VisualDSP++ Linker & Utilities Manual for ADSP-218x DSPs
All the manuals are included in the software distribution CD-ROM. To
access these manuals, use the Help Topics command in the VisualDSP
environment’s Help menu and select the Online Manuals book. From this
Help topic, you can open any of the manuals, which are in Adobe Acrobat
PDF format.
Conventions
Throughout this manual there are tables summarizing the syntax of the
instruction groups. Table 1-1 identifies the notation conventions that
apply to all chapters. Note that additional conventions, which apply only
to specific chapters, may appear throughout this manual.
1-8
ADSP-218x DSP Instruction Set Reference
Introduction
Table 1-1. Instruction Set Notation
Notation
Meaning
UPPERCASE
Explicit syntax—assembler keyword. The assembler is caseinsensitive.
;
A semicolon terminates an instruction line.
,
A comma separates multiple, parallel instructions in the same
instruction line.
// single line comment
/* multi line comment */
// or /* */ indicate comments or remarks that explain program code,
but that the assembler ignores. For more details, see the VisualDSP++ Assembler Manual for ADSP-218x DSPs.
operands
Some instruction operands are shown in lowercase letters. These
operands may take different values in assembly code. For example,
the operand yop may be one of several registers: AY0, AY1, or AF.
<exp>
Denotes exponent (shift value) in Shift Immediate instructions;
must be an 8-bit signed integer constant.
<data>
Denotes an immediate data value.
<addr>
Denotes an immediate address value to be encoded in the instruction. The <addr> may be either an immediate value (a constant) or a
program label.
<reg>
Refers to any accessible register; see Table 4-7 “Processor Registers:
reg and dreg” on page 4-22.
[brackets]
Refers to optional instruction extensions
<dreg>
Refers to any data register; see Table 4-7 “Processor Registers: reg
and dreg” on page 4-22.
0x
Denotes number in hexadecimal format (0xFFFF).
h#
Denotes number in hexadecimal format (h#FFFF).
b#
Denotes number in binary format (b#0001000100010001).
ADSP-218x DSP Instruction Set Reference
1-9
Conventions
Table 1-1. Instruction Set Notation (Cont’d)
Notation
L
[
Meaning
A note, providing information of special interest or identifying a
related topic. In the online version of this book, the word Note
appears instead of this symbol.
A caution, providing information about critical design or programming issues that influence operation of a product. In the online version of this book, the word Caution appears instead of this symbol.
Immediate values such as <exp>, <data>, or <addr> may be a constant in
decimal, hexadecimal, octal or binary format. The default format is
decimal.
1-10
ADSP-218x DSP Instruction Set Reference
2 PROGRAMMING MODEL
This chapter provides an overview of ADSP-218x registers and their operations used in processor programming.
This chapter contains:
• “Overview” on page 2-1
• “Program Example” on page 2-10
• “Hardware Overlays and Software Issues” on page 2-16
Overview
From a programming standpoint, the ADSP-218x DSPs consist of three
computational units (ALU, MAC and Shifter), two data address generators, and a program sequencer, plus on-chip peripherals and memory that
vary with each processor. Almost all operations using these architectural
components require one or more registers to store data, to keep track of
values such as pointers, or to specify operating modes.
Internal registers hold data, addresses, control information or status information. For example, AX0 stores an ALU operand (data); I4 stores a
DAG2 pointer (address); ASTAT contains status flags from arithmetic operations; fields in the wait state register control the number of wait states for
different zones of external memory.
ADSP-218x DSP Instruction Set Reference
2-1
Overview
There are two types of accesses for registers. The first type of access is
made to dedicated registers such as MX0 and IMASK. These registers can be
read and written explicitly in assembly language. For example,
MX0=1234;
IMASK=0xF;
The second type of access is made to memory-mapped registers such as the
system control register, wait state control register, timer registers and
SPORT registers. These registers are accessed by reading and writing the
corresponding data memory locations.
For example, the following code clears the Wait State Control Register,
which is mapped to data memory location 0x3FFE:
AX0=0;
DM(0x3FFE)=AX0;
In this example, AX0 is used to hold the constant 0 because there is no
instruction to write an immediate data value to memory using an immediate address.
The ADSP-218x registers are shown in Figure 2-1. The registers are
grouped by function: data address generators (DAGs), program sequencer,
computational units (ALU, MAC, and shifter), bus exchange (PX), memory interface, timer, SPORTs, host interface, and DMA interface.
Data Address Generators
DAG1 and DAG2 each have twelve 14-bit registers: four index (I) registers for storing pointers, four modify (M) registers for updating pointers
and four length (L) registers for implementing circular buffers. DAG1
addresses data memory only and has the capability of bit-reversing its outputs. DAG2 addresses both program and data memory and can provide
addresses for indirect branching (jumps and calls) as well as for accessing
data.
2-2
ADSP-218x DSP Instruction Set Reference
Programming Model
Processor Core
DATA ADDRESS GENERATORS
DAG1
(DM addressing only)
DAG2
(DM and PM addressing)
Bit-reverse capability
Indirect branch capability
TIMER
MEMORY INTERFACE
0x3FFD TPERIOD
I0
L0
M0
I4
L4
M4
I1
L1
M1
I5
L5
M5
I2
L2
M2
I6
L6
M6
I3
L3
14
M3
14
I7
14
L7
M7
14
14
14
0x3FFC TCOUNT
0x3FFB TSCALE
System Control
Register
Wait
States
4
4
DMOVLAY PMOVLAY
0x3FFF
0x3FFE
SPORT 0
PROGRAM SEQUENCER
18
5
LOOP
STACK
4 X 18
14
ICNTL
16
IFC*
14
RX0
OWRCNTR
0x3FFA
10
7
CNT
IMASK* MSTAT*
ASTAT
R
COUNT
STACK
STATUS STACK*
4X
14
* Status Stack Depth = 12 memory locations, Width = 25
bits
ALU
MAC
AX0 AX1
AY0 AY1
MX0 MX1
8
AR
AF
MY
0
MY1
MR2 MR1 MR0
MF
16
16
TX0
Multichannel enables
PC
STACK
16 X
14 8
SSTA
8T
0x3FF9
RX 3116 15-0
RX
0x3FF8
TX 31-16
TX 150
SPORT0 Control
0x3FF
Control
0x3FF7
6
0x3FF
5
0x3FF
SCLKDIV
4
0x3FF
3
Autobuffer
RFSDIV
SHIFTER
8
SI
BUS EXCHANGE
5
SE
8
SB
PX
IDMA Registers
Control
0x3FE0 IDMA
Register
RX1
TX1
0x3FF2
Control
0x3FF1
SCLKDIV
BDMA Registers
0x3FE BWCOUNT
4
0x3FE3 BDMA Control
Programmable
Flag Registers
0x3FE2
BEAD
0x3FE6
PFTYPE
0x3FE1
BIAD
0x3FE5
PFDATA
SPORT 1
SPORT1 Control
16
IDMA PORT
BDMA PORT
PROGRAMMABLE FLAGS
RFSDIV
0x3FF0
0x3FEF Autobuffer
SR1 SR0
Figure 2-1. ADSP-218x DSP Registers
ADSP-218x DSP Instruction Set Reference
2-3
Overview
The following example is an indirect data memory read from the location
pointed to by I0. Once the read is complete, I0 is updated by M0.
AX0=DM(I0,M0);
The following example is an indirect program memory data write to the
address pointed to by I4 with a post modify by M5:
PM(I4,M5)=MR1;
The following example is an example of an indirect jump:
JUMP (I4);
Always Initialize L Registers
The ADSP-218x processors allow two addressing modes for data memory
accesses: direct and register indirect. Indirect addressing is accomplished
by loading an address into an I (index) register and specifying one of the
available M (modify) registers.
The L registers are provided to facilitate wraparound addressing of circular
data buffers. A circular buffer is only implemented when an L register is
set to a non-zero value.
linear(that is, non-circular) indirect addressing, the register
[ For
corresponding to the register used must be set to zero. Do not
L
I
assume that the L registers are automatically initialized or may be
ignored; the I, M, and L registers contain random values following
processor reset. Your program must initialize the L registers corresponding to any I registers it uses.
Program Sequencer
Registers associated with the program sequencer control subroutines,
loops, and interrupts. They also indicate status and select modes of
operation.
2-4
ADSP-218x DSP Instruction Set Reference
Programming Model
Interrupts
The ICNTL register controls interrupt nesting and external interrupt sensitivity. The IFC register which is 16 bits wide lets you force and clear
interrupts in software. The IMASK register which is 10 bits wide masks (disables) individual interrupts. ADSP-218x processors support twelve
interrupts, two of which (reset, powerdown) are non-maskable.
The ADSP-2181 DSP supports a global interrupt enable instruction (ENA
INTS) and interrupt disable instruction ( DIS INTS). Executing the disable
interrupt instruction causes all interrupts to be masked without changing
the contents of the IMASK register. Disabling interrupts does not affect
serial port autobuffering, which operate normally whether or not interrupts are enabled. The disable interrupt instruction masks all user
interrupts including the powerdown interrupt. The interrupt enable
instruction allows all unmasked interrupts to be serviced again.
Loop Counts
The CNTR register stores the count value for the currently executing loop.
The count stack allows the nesting of count-based loops to four levels. A
write to CNTR pushes the current value onto the count stack before writing
the new value. The following example pushes the current value of CNTR on
the count stack and then loads CNTR with 10.
CNTR=10;
is a special syntax with which you can overwrite the count value
for the current loop without pushing CNTR on the count stack.
OWRCNTR
be read (for example, used as a source register), and
L must notcannot
be written in the last instruction of a
loop.
OWRCNTR
DO UNTIL
ADSP-218x DSP Instruction Set Reference
2-5
Overview
Status and Mode Bits
The stack status (SSTAT) register contains full and empty flags for stacks.
The arithmetic status (ASTAT) register contains status flags for the computational units. The mode status (MSTAT) register contains control bits for
various options. MSTAT contains 4 bits that control alternate register selection for the computational units, bit-reverse mode for DAG1, and overflow
latch and saturation modes for the ALU. MSTAT also has 3 bits to control
the MAC result placement, timer enable, and Go mode enable.
Use the Mode Control instruction (ENA or
disable processor modes.
DIS)
to conveniently enable or
Stacks
The program sequencer contains four stacks that allow loop, subroutine
and interrupt nesting.
The PC stack is 14 bits wide and 16 locations deep. It stores return
addresses for subroutines and interrupt service routines, and top-of-loop
addresses for loops. PC stack handling is automatic for subroutine calls
and interrupt handling. In addition, the PC stack can be manually pushed
or popped using the PC Stack Control instructions TOPPCSTACK=reg and
reg=TOPPCSTACK.
The loop stack is 18 bits wide, 14 bits for the end-of-loop address and 4
bits for the termination condition code. The loop stack is four locations
deep. It is automatically pushed during the execution of a DO UNTIL
instruction. It is popped automatically during a loop exit if the loop was
nested. The loop stack may be manually popped with the POP LOOP
instruction.
The status stack, which is automatically pushed when the processor services an interrupt, accommodates the interrupt mask (IMASK), mode status
(MSTAT) and arithmetic status (ASTAT) registers. The depth and width of
the status stack varies with each processor, since each of the processors has
2-6
ADSP-218x DSP Instruction Set Reference
Programming Model
a different numbers of interrupts. The status stack is automatically popped
when the return from interrupt (RTI) instruction is executed. The status
stack can be pushed and popped manually with the PUSH STS and POP STS
instructions.
The count stack is 14 bits wide and holds counter (CNTR) values for nested
counter-based loops. This stack is pushed automatically with the current
CNTR value when there is a write to CNTR. The counter stack may be manually popped with the POP CNTR instruction.
Computational Units
The registers in the computational units store data. The ALU and MAC
require two inputs for most operations. The AX0, AX1, MX0, and MX1 registers store X inputs, and the AY0, AY1, MY0, and MY1 registers store Y inputs.
The AR and AF registers store ALU results; AF can be fed back to the ALU Y
input, whereas AR can provide the X input of any computational unit.
Likewise, the MR0, MR1, MR2, and MF register store MAC results and can be
fed back for other computations. The 16-bit MR0 and MR1 registers together
with the 8-bit MR2 register can store a 40-bit multiply/accumulate result.
The shifter can receive input from the ALU or MAC, from its own result
registers, or from a dedicated shifter input (SI) register. It can store a
32-bit result in the SR0 and SR1 registers. The SB register stores the block
exponent for block floating-point operations. The SE register holds the
shift value for normalize and denormalize operations.
Registers in the computational units have secondary registers, shown in
Figure 2-1 on page 2-3 as second set of registers behind the first set. Secondary registers are useful for single-cycle context switches. The selection
of these secondary registers is controlled by a bit in the MSTAT register; the
bit is set and cleared by these instructions:
ENA SEC_REG;
/*select secondary registers*/
DIS SEC_REG;
/*select primary registers*/
ADSP-218x DSP Instruction Set Reference
2-7
Overview
Bus Exchange
The PX register is an 8-bit register that allows data transfers between the
16-bit DMD bus and the 24-bit PMD bus. In a transfer between program
memory and a 16-bit register, PX provides or receives the lower eight bits
implicitly.
Timer
The TPERIOD, TCOUNT, and TSCALE hold the timer period, count, and scale
factor values, respectively. These registers are memory-mapped at locations 0x3FFD, 0x3FFC, and 0x3FFB respectively.
Serial Ports
SPORT0 and SPORT1 each have receive (RX), transmit (TX) and control
registers. The control registers are memory-mapped registers at locations
0x3FEF through 0x3FFA in data memory. SPORT0 also has registers for
controlling its multichannel functions. Each SPORT control register contains bits that control frame synchronization, companding, word length
and, in SPORT0, multichannel options. The SCLKDIV register for each
SPORT determines the frequency of the internally generated serial clock,
and the RFSDIV register determines the frequency of the internally generated receive frame sync signal for each SPORT. The autobuffer registers
control autobuffering in each SPORT.
Programming a SPORT consists of writing to its control register and,
depending on the modes selected, writing to its SCLKDIV and/or RFSDIV
registers as well. The following example code may be used to program
SPORT0 for 8-bit µ-law companding with normal framing and an internally generated serial clock. RFSDIV is set to 255 for 256 SCLK cycles
between RFS assertions. SCLKDIV is set to 2, resulting in an SCLK frequency
that is 1/6 of the CLKIN frequency.
2-8
ADSP-218x DSP Instruction Set Reference
Programming Model
SI=0xB27;
DM(0X3FF6)=SI;
/*SPORT0 control register*/
SI=2;
DM(0x3FF5)=SI;
/*SCLKDIV = 2*/
SI=255;
DM(0x3FF4)=SI;
/*RFSDIV = 255*/
Memory Interface and SPORT Enables
The system control register, memory-mapped at DM(0x3fff), contains
SPORT0 and SPORT1 enable bits (bits 12 and 11 respectively) as well as
the SPORT1 configuration selection bit (bit 10). On all ADSP-218x processors, the system control register also contains fields for external
program memory wait states. For the following processors, the system
control register contains the disable BMS bit, which allows the external signal BMS to be disabled during byte memory accesses.
This feature can be used, for example, to allow the DSP to boot from an
EPROM and then access a Flash memory, or other byte-wide device, at
runtime via the CMS signal.
ADSP-2184
ADSP-2184L
ADSP-2185M
ADSP-2184N
ADSP-2186
ADSP-2185L
ADSP-2186M
ADSP-2185N
ADSP-2186L
ADSP-2188M
ADSP-2186N
ADSP-2187L
ADSP-2189 M
ADSP-2187N
ADSP-2188N
ADSP-2189 N
The wait state control register, memory-mapped at DM(0x3ffe), contains
fields that specify the number of wait states for external data memory, and
four banks of external I/O memory space.
ADSP-218x DSP Instruction Set Reference
2-9
Program Example
On the following processors, bit 15 of the register, the wait state mode
select bit, determines whether the assigned wait state value operates in a
“1x” or “2x+1” mode:
ADSP-2185M
ADSP-2185N
ADSP-2186M
ADSP-2186N
ADSP-2188M
ADSP-2187N
ADSP-2189M
ADSP-2188N
ADSP-2189N
Other memory-mapped registers control the IDMA port and byte memory DMA (BDMA) port for booting and runtime operations. These
registers can be used in many ways that includes selecting the byte memory page, operating in data packing mode, or forcing the boot from
software.
Program Example
Listing 2-1 presents an example of an FIR filter program written for the
ADSP-2181 DSP followed by a discussion of each part of the program.
The program can also be executed on any other ADSP-218x processor,
with minor modifications. This FIR filter program demonstrates much of
the conceptual power of the ADSP-218x architecture and instruction set.
Listing 2-1. Include File, Constants Initialization
/*ADSP-2181 FIR Filter Routine
-serial port 0 used for I/O
-internally generated serial clock
-40.000 MHz processor clock rate is divided to generate a
1.5385 MHz serial clock
-serial clock divided to 8 kHz frame sampling rate*/
2-10
ADSP-218x DSP Instruction Set Reference
Programming Model
See Notes: Section A
#include <def2181.h>
#define taps 15
#define taps_less_one 14
See Notes: Section B
.section/dmdm_data;
.var/circdata_buffer[taps];
/* dm data buffer */
.section/pmpm_data;
.var/circ/init24coefficient[taps] = "coeff.dat";
.section/pm
Interrupts;
See Notes: Section C
start:
jump main; rti; rti; rti;
rti; rti; rti; rti;
/* 0x0000: ~Reset vector */
/* 0x0004: ~IRQ2
rti; rti; rti; rti;
*/
/* 0x0008: ~IRQL1 */
rti; rti; rti; rti;
/* 0x000c: ~IRQL0 */
rti; rti; rti; rti;
/* 0x0010: SPORT0 Transmit */
jump fir_start; rti; rti; rti; /* 0x0014: SPORT0 Receive
rti; rti; rti; rti;
*/
/* 0x0018: ~IRQE */
rti; rti; rti; rti;
/* 0x001c: BDMA
*/
rti; rti; rti; rti;
/* 0x0020: SPORT1 Transmit or ~IRQ1 */
rti; rti; rti; rti;
/* 0x0024: SPORT1 Receive or ~IRQ0
rti; rti; rti; rti;
/* 0x0028: Timer */
rti; rti; rti; rti;
/* 0x002c: Power Down (non-maskable */
.section/pm
pm_code;
*/
See Notes: Section D
main:
l0 = length (data_buffer);
/* setup circular buffer length */
l4 = length (coefficient);
/*setup circular buffer */
m0 = 1;
/* modify =1 for increment
m4 = 1;
*/
/* through buffers */
ADSP-218x DSP Instruction Set Reference
2-11
Program Example
i0 = data_buffer;
/* point to start of buffer */
i4 = coefficient;
/* point to start of buffer */
ax0 = 0;
cntr = length(data_buffer);
/* initialize loop counter */
do clear until ce;
clear: dm(i0,m0) = ax0;
/* clear data buffer */
/* setup divide value for 8KHz RFS */
See Notes: Section E
ax0 = 0x00c0;
dm(Sport0_Rfsdiv) = ax0;
/* 1.5385 MHz internal serial clock */
ax0 = 0x000c;
dm(Sport0_Sclkdiv) = ax0;
/* multichannel disabled, internally generated sclk,
receive frame sync required, receive width = 0, transmit
frame sync required, transmit width = 0,
external transmit frame sync, internal receive frame
sync,u-law companding, 8-bit words */
ax0 = 0x69b7;
dm(Sport0_Ctrl_Reg) = ax0;
ax0 = 0x1000;
/* enable sport0 */
dm(Sys_Ctrl_Reg) = ax0;
icntl = 0x00;
/* disable interrupt nesting */
imask = 0x0060;
/* enable sport0 rx and tx interrupts only */
2-12
ADSP-218x DSP Instruction Set Reference
Programming Model
mainloop:
idle;
/* wait here for interrupt */
jump mainloop;
/* jump back to idle after rti */
Example Program: Setup Routine Discussion
The setup and main loop routine performs initialization and then loops
on the IDLE instruction to wait until the receive interrupt from SPORT0
occurs. The filter is interrupt-driven. When the interrupt occurs, control
shifts to the interrupt service routine shown in Listing 2-2.
NOTES:
Section A of the program declares two constants and includes a header file
of definitions named def2181.h.
Section B of the program includes the assembler directives defining two
circular buffers in on-chip memory: one in data memory RAM that is used
to hold a delay line of samples and one in program memory RAM that is
used to store coefficients for the filter. The coefficients are actually loaded
from an external file by the linker. These values can be changed without
reassembling; only another linking is required.
Section C shows the setup of interrupts. The first instruction is placed at
the reset vector: address PM (0x0000). The first location is the reset vector
instruction, which jumps to main. Interrupt vectors that are not used are
filled with a return from interrupt instruction. This is a preferred programming practice rather than a necessity. The SPORT0 receive interrupt
vector jumps to the interrupt service routine.
Section D, main, sets up the index (I), length (L), and modify (M) registers
used to address the two circular buffers. A non-zero value for length activates the processor’s modulus logic. Each time the interrupt occurs, the I
register pointers advance one position through the buffers. The clear loop
sets all values in the data memory buffer to zero.
ADSP-218x DSP Instruction Set Reference
2-13
Program Example
Section E sets up the processor’s memory-mapped control registers used in
this system. See Appendix B in the ADSP-218x Hardware Reference Manual for control register initialization information.
SPORT0 is set up to generate the serial clock internally at 1.5385 MHz,
based on a processor clock rate of 40 MHz. The receive and transmit signals are both required. The receive signal is generated internally at 8
KHz, while the transmit signal comes from the external device communicating with the processor.
Finally, SPORT0 is enabled and the interrupts are enabled. Now the IDLE
instruction causes the processor to wait for interrupts. After the return
from interrupt instruction, execution resumes at the instruction following
the IDLE instruction. Once these setup instructions have been executed, all
further activity takes place in the interrupt service routine shown in
Listing 2-2.
Listing 2-2. Interrupt Routine
fir_start:
si = rx0;
/* read from sport0 */
dm(i0,m0) = si;
/* transfer data to buffer */
mr = 0, my0 = pm(i4,m4), mx0 = dm(i0,m0);
/* setup multiplier for loop */
cntr = taps_less_one;
/* perform loop taps-1 times */
do convolution until ce;
convolution:
mr = mr + mx0 * my0 (ss), my0 = pm(i4,m4), mx0 = dm(i0,m0);
/* perform MAC and fetch next values */
mr = mr + mx0 * my0 (rnd);
/* Nth pass of loop with rounding of result */
if mv sat mr;
tx0 = mr1;
rti;
2-14
/* write result to sport0 tx */
/* return from interrupt */
ADSP-218x DSP Instruction Set Reference
Programming Model
Example Program: Interrupt Routine Discussion
This subroutine transfers the received data to the next location in the circular buffer overwriting the oldest sample. All samples and coefficients are
then multiplied and the products are accumulated to produce the next
output value. The subroutine checks for overflow and saturates the output
value to the appropriate full scale. It then writes the result to the transmit
section of SPORT0 and returns.
The subroutine begins by reading a new sample from SPORT0’s receive
data register, RX0, into the SI register. The choice of SI is of no particular
significance. Then, the data is written into the data buffer. Because of the
automatic circular buffer addressing, the new data overwrites the oldest
sample. The N-most recent samples are always in the buffer.
The third instruction of the routine, MR=0, MY0=PM(I4,M4),
clears the multiplier result register (MR) and fetches the
first two operands. This instruction accesses both program and data memory but still executes in a single cycle because of the processor’s
architecture. The counter register (CNTR) directs the loop to be performed
taps-1 times.
MX0=DM(I0,M0),
The convolution label identifies the loop itself, consisting of only two
instructions, one instruction setting up the loop (DO UNTIL) and one
instruction nested in the loop. The MAC instruction multiplies and accumulates the previous set of operands while fetching the next ones from
each memory. This instruction also accesses both memories.
The final result is written back to the SPORT0 transmit data register TX0
to be sent to the communicating device.
ADSP-218x DSP Instruction Set Reference
2-15
Hardware Overlays and Software Issues
Hardware Overlays and Software Issues
Hardware overlay pages can be used for both program execution and data
storage. Switching between hardware overlay memory pages can be done
in a single processor cycle with no effect latencies. The following examples
show the assembly instructions for managing different program memory
hardware overlay regions:
pmovlay = ax0;
pmovlay = 5;
Since the program memory hardware overlay regions reside in address
locations PM 0x2000 through 0x3fff, programs are restricted to execute
the pmovlay= instruction from within the fixed program memory region,
located at addresses PM 0x0000 through 0x1FFF.
If a pmovlay = instruction were to be executed from a program memory
hardware overlay page, the next instruction would be fetched and executed
from the subsequent address of the new hardware overlay page. In this scenario, there is no possibility to specify a well-defined address of the target
program memory overlay region. Therefore, the portion of your program
that controls the management of the program memory overlay pages must
reside within the fixed/non-overlay program memory region.
If the program flow requires execution from a module that resides in an
overlay region, it is good programming practice to have the calling function access the overlay module using a CALL instruction versus a JUMP
instruction. Executing a call instruction pushes the address of the subsequent address after the call instruction onto the program counter stack,
which is the return address after the overlay module is completed. Upon
return from the overlay subroutine via the rts instruction, program execution resumse with the instruction following the subroutine call.
2-16
ADSP-218x DSP Instruction Set Reference
Programming Model
The example below shows one application of switching between program
memory overlay regions at runtime:
main:
. . .
pmovlay = 4;
/* switch to PM overlay #4 */
call Ovl4Function;
pmovlay = 5;
/* call overlay function
*/
/* return from overlay #4 & goto overlay #5 */
call Ovl5Function;
/* call overlay function */
. . .
Libraries and Overlays
Because the program sequencer works independently from the program
memory overlay register (PMOVLAY), program modules that run within an
overlay page have no direct access to any program modules resident in
other overlay pages. This means that all the required libraries and
sub-functions must be placed either in the same page as the calling function or in the fixed memory/non-overlay area. Place libraries that are used
by multiple modules located in different pages in the fixed program memory region as well. Unfortunately, for some applications there is a limited
amount of fixed program memory. In this case, the linker places parts of
the library in different overlay pages to help balance the memory usage in
the system.
Interrupts and Overlays
The interrupt vector table occupies program memory addresses 0x0000
through 0x002f. When an unmasked interrupt is raised, ASTAT, MSTAT and
IMASK are pushed onto the status stack in this specific order. The current
value of the program counter which contains the address of the next
instruction is placed onto the PC stack. This allows the program execution
to continue with the next instruction of the main program after the interrupt is serviced.
ADSP-218x DSP Instruction Set Reference
2-17
Hardware Overlays and Software Issues
The ADSP-218x interrupt controller has no knowledge of the PMOVLAY
and DMOVLAY registers. Therefore, the values of these registers must be
saved or restored by the programmer in the interrupt service routine.
Whenever the interrupt service routine is located within the fixed program
memory region, no special context saving of the overlay registers is
required. However, if you would like to place the ISR within an overlay
page, some additional instructions are needed to facilitate the saving or
restoring of the PMOVLAY and DMOVLAY registers. The interrupt vector table
features only four instruction locations per interrupt. Listing 2-3 is an
example of a four instruction implementation that restores the PMOVLAY
register after an interrupt.
Listing 2-3. PMOVLAY Register Restoration
Interrupt Vector:
ax0 = PMOVLAY;
/* save PMOVLAY value into ax0
Toppcstack = ax0;
/* push PMOVLAY value onto PC stack */
Jump My_ISR;
/* jump to interrupt subroutine
Rti;
/* placeholder in vector table (4 locations total
*/
*/
*/
My_ISR:
/* ISR code goes here */
jump I_Handler;
/* use instead of rti to restore PMOVLAY
reg */
I_Handler:
/* this subroutine should reside in fixed PM */
ax0 = Toppcstack;
/* pop PMOVLAY value into ax0
*/
nop;
/* one cycle effect latency
*/
rti;
/* return from interrupt
*/
If the interrupt service routine also accesses alternate data memory overlay
pages, the DMOVLAY register must be saved and restored like the PMOVLAY
register. Listing 2-4 is an example of a DMOVLAY register restoration.
2-18
ADSP-218x DSP Instruction Set Reference
Programming Model
Listing 2-4. DMOVLAY Register Restoration
Interrupt Vector:
jump I_Handler;
/* jump to interrupt handler */
rti;
/* unreachable instructions
rti;
/* used as placeholders to
rti;
I_Handler:
*/
*/
/* occupy all 4 locations of the vector */
/* this subroutine should reside in fixed PM */
ax0 = PMOVLAY;
/* save PMOVLAY value into ax0 */
dm(save_PMOVLY)= ax0;/* save PMOVLAY value to DM variable*/
ax0 = DMOVLAY;
/* save DMOVLAY value into ax0
*/
dm(save_DMOVLY)= ax0;/*save DMOVLAY value to DM variable */
PMOVLAY = 5;
/* isr is in PM page 5
*/
DMOVLAY = 4;
/* isr accesses DM page 4
*/
call My_ISR;
ax0 = dm(save_DMOVLY);
/* return from isr and restore DMOVLAY */
DMOVLAY = ax0;
/* restore DMOVLAY value */
ax0 = dm(save_PMOVLY);
/* restore “saved” PMOVLAY from memory */
PMOVLAY = ax0;
/* restore PMOVLAY value
*/
rti;
/* return from interrupt
*/
My_ISR:
rts;
/* isr code goes here
*/
/* return to I_Handler instead of rti
*/
Loop Hardware and Overlays
The loop hardware of the ADSP-218x DSPs operates independent of the
PMOVLAY register. Once a DO UNTIL instruction has been executed, the loop
comparator compares the next address generated by the program
sequencer to the address of the last instruction of the loop. The loop com-
ADSP-218x DSP Instruction Set Reference
2-19
Hardware Overlays and Software Issues
pares the address value only. This comparison is performed independently
from the value of the PMOVLAY register. Whenever the PMOVLAY register is
updated to point to another overlay page while a loop in another overlay
page is still active, the loop comparator may detect an end-of-loop address
and force the PC to branch to an undesired memory location. In a real system design, this scenario may happen when a loop within an overlay page
is exited temporarily by an interrupt service routine that runs in a different
overlay page.
memory region for program memory occupies addresses
L The fixedthrough
; the program memory overlay region occu0x0000
0x1fff
pies addresses 0x2000 through 0x3fff.
To avoid the improper execution of a loop:
• Place hardware loops either in the fixed program memory or in
overlay pages. Do not place loops whose loop bodies cross the
boundary between program memory and an overlay page.
• Always place interrupt service routines in fixed program memory or
in non-overlay program memory.
• Avoid end-of-loop addresses in ISRs.
2-20
ADSP-218x DSP Instruction Set Reference
3 SOFTWARE EXAMPLES
This chapter provides a brief summary of the development process that
you use to create executable programs for the ADSP-218x DSPs. The
overview is followed by software examples that you can use as a guide
when writing your own applications.
The chapter contains:
• “Overview” on page 3-1
• “System Development Process” on page 3-3
• “Single-Precision Fir Transversal Filter” on page 3-5
• “Cascaded Biquad IIR Filter” on page 3-7
• “Sine Approximation” on page 3-9
• “Single-Precision Matrix Multiply” on page 3-11
• “Radix-2 Decimation-in-Time FFT” on page 3-13
Refer to the VisualDSP++ 3.5 Compiler amd Library Manual for
ADSP-218x DSPs for information on appropriate library functions.
Overview
The software examples presented in this chapter are used for a variety of
DSP operations. The FIR filter and cascaded biquad IIR filter are general
filter algorithms that can be tailored to many applications. Matrix multiplication is used in image processing and other areas requiring vector
ADSP-218x DSP Instruction Set Reference
3-1
Overview
operations. The sine function is required for many scientific calculations.
The FFT (fast Fourier transform) has wide application in signal analysis.
Each of these examples is described in greater detail in Digital Signal Processing Applications Using The ADSP-2100 Family, Volume1, available
from our website at www.analog.com. They are presented here to show
some aspects of typical programs.
The FFT example is a complete program, including a subroutine that performs the FFT, a main calling program that initializes registers and calls
the FFT subroutine, and an auxiliary routine.
Each of the other examples is shown as a subroutine in its own module.
The module starts with a .SECTION assignment for data or code, using the
section name defined in the .LDF file. The subroutine can be called from a
program in another module that declares the starting label of the subroutine as an external symbol .EXTERN. This is the same label that is declared
with the .GLOBAL directive in the subroutine module. This makes the subroutine callable from routines defined in other .ASM files. The last
instruction in each subroutine is the RTS instruction, which returns control to the calling program.
Each module is prefaced by a comment block that provides the information shown in Table 3-1.
Table 3-1. Subroutine Modules and Comment Information
3-2
Module
Comment Information
Calling Parameters
Register values that the calling program must set before
calling the subroutine
Return Values
Registers that hold the results of the subroutine
Altered Registers
Register used by the subroutine. The calling program
must save them before calling the subroutine and restore
them afterward in order to preserve their values
Computation Time
The number of instruction cycles needed to perform the
subroutine
ADSP-218x DSP Instruction Set Reference
Software Examples
System Development Process
The ADSP-218x DSPs are supported by a complete set of development
tools. Programming aids and processor simulators facilitate software
design and debug. In-circuit emulators and demonstration boards help in
hardware prototyping.
Figure 3-1 shows a flow chart of the system development process.
L in ke r
Descript io n File
(. LDF)
Step 1: Architecture D es cription
Step 2: C ode Generation
G ene rat e
Assem bly
S ource
(.DSP, . ASM)
Asse mbler
EASM2 18x
(. DOJ)
L in ker
linker.exe
and/or
Gene ra te C
So urce
(.C)
C Com piler
cc218x
(. DX E)
VisualDSP
De bugg er
de bu gapp
Step 3: Sys tem V erification
Ha rd wa re Evaluat io n
EZ-Kit L it e
Target V erification
EZ-ICE
Step 4: Software Verification
NO
Working
Cod e?
YES
ROM Pro duction
E LFS PL21
Figure 3-1. ADSP-218x DSP System Development Process
Software development tools include a C Compiler, C Runtime Library,
DSP and Math Libraries, Assembler, Linker, Loader, Simulator, and Splitter. These tools are described in detail in the following documents:
• VisualDSP++ Assembler and Preprocessor Manual for ADSP-218x
DSPs
• VisualDSP++ C Compiler & Library Manual for ADSP-218x DSPs
ADSP-218x DSP Instruction Set Reference
3-3
System Development Process
• Product Bulletin for VisualDSP++ and ADSP-218x DSPs
• VisualDSP++ User’s Manual for ADSP-218x DSPs
• VisualDSP++ Linker & Utilities Manual for ADSP-218 DSPs
These documents are included in the software distribution CD-ROM and
can be downloaded from our website at www.analog.com.
The development process begins with the task of describing the system
and generating source code. You describe the system in the Linker
Description File (.LDF) and you generate source code in C and/or assembly language.
Describing the system in the .LDF file includes providing information
about the hardware environment and memory layout. Refer to the
VisualDSP++ Linker & Utilities Manual for ADSP-218x DSPs for details.
Generating source code requires creating code modules, which can be
written in either assembly language or C language. These modules include
a main program, subroutines, or data variable declarations. The C modules are compiled by the C compiler cc218x.exe. Each code module is
assembled separately by the assembler, which produces an object file
(.DOJ).
The .DOJ file is input to the Linker linker.exe, along with the .LDF file.
The linker links several object modules together to form an executable
program .DXE. The linker reads the target hardware information from the
.LDF file to determine appropriate addresses for code and data. You specify
the segment your code or data belongs to in the assembly file. You specify
the location of the segment in the .LDF file.
The linker places non-relocatable code or data modules at the specified
memory addresses, provided the memory area has the correct attributes.
The linker selects addresses for relocatable object. The linker generates a
3-4
ADSP-218x DSP Instruction Set Reference
Software Examples
memory image file .DXE containing a single executable program, which
may be loaded into a VisualDSP debugger session (simulator or emulator)
for testing.
The simulator provides windows that display different portions of the
hardware environment. To replicate the target hardware, the simulator
configures memory according to the memory specification in the .LDF
file. The resulting simulation allows you to debug the system and analyze
performance before committing to a hardware prototype.
After fully simulating your system and software, you can use an EZ-ICE
in-circuit emulator in the prototype hardware to test circuitry, timing, and
real-time software execution.
The PROM splitter software tool elfpsl21.exe translates the .DXE file
into an industry-standard file format for a PROM programmer. Once you
program the code in PROM devices and install an ADSP-218x processor
into your prototype, it is ready to run.
Single-Precision Fir Transversal Filter
An FIR transversal filter structure can be obtained directly from the equation for discrete-time convolution:
N–1
y(n) ≡
∑
h k ( n )x ( n – k )
k=0
In this equation, x(n) and y(n) represent the input to and output from
the filter at time n. The output y(n) is formed as a weighted linear combination of the current and past input values of x, x(n–k). The weights,
hk(n), are the transversal filter coefficients at time n.
ADSP-218x DSP Instruction Set Reference
3-5
Single-Precision Fir Transversal Filter
In the equation, x(n–k) represents the past value of the input signal “contained” in the (k+1)th tap of the transversal filter. For example, x(n), the
present value of the input signal, would correspond to the first tap, while
x(n–42) would correspond to the forty-third filter tap.
The subroutine that realizes the sum-of-products operation used in computing the transversal filter is shown in Listing 3-1.
Listing 3-1. Single-Precision FIR Transversal Filter
.SECTION/CODE program;
/*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*/
3-6
FIR Transversal Filter Subroutine
Calling Parameters
I0 -> Oldest input data value in delay line
L0 = Filter length (N)
I4 -> Beginning of filter coefficient table
L4 = Filter length (N)
M1,M5 = 1
CNTR = Filter length - 1 (N-1)
Return Values
MR1 = Sum of products (rounded and saturated)
I0 -> Oldest input data value in delay line
I4 -> Beginning of filter coefficient table
Altered Registers
MX0,MY0,MR
Computation Time
N - 1 + 5 + 2 cycles
All coefficients and data values are assumed to be
in 1.15 format.
ADSP-218x DSP Instruction Set Reference
Software Examples
.GLOBAL fir;
fir:
sop:
MR=0, MX0=DM(I0,M1), MY0=PM(I4,M5);
DO sop UNTIL CE;
MR=MR+MX0*MY0(SS), MX0=DM(I0,M1), MY0=PM(I4,M5);
MR=MR+MX0*MY0(RND);
IF MV SAT MR;
RTS;
Cascaded Biquad IIR Filter
A second-order biquad IIR filter section is represented by the transfer
function (in the z-domain):
H(z) = Y(z)/X(z) = ( B0+ B1 z
–1+ B z –2)/( 1 + A z–1+ A z –2)
2
1
2
where A1, A2, B0, B1 and B2 are coefficients that determine the desired
impulse response of the system H(z). The corresponding difference equation for a biquad section is:
Y(n) = B0X(n) + B1X(n–1) + B2 X(n–2) – A1 Y(n–1) – A2 Y(n–2)
Higher-order filters can be obtained by cascading several biquad sections
with appropriate coefficients. The biquad sections can be scaled separately
and then cascaded in order to minimize the coefficient quantization and
the recursive accumulation errors.
A subroutine that implements a high-order filter is shown in Listing 3-2.
A circular buffer in program memory contains the scaled biquad coefficients. These coefficients are stored in the order: B2, B1. B0, A2 and A1 for
each biquad. The individual biquad coefficient groups must be stored in
the order that the biquads are cascaded.
ADSP-218x DSP Instruction Set Reference
3-7
Cascaded Biquad IIR Filter
Listing 3-2. Cascaded Biquad IIR Filter
.SECTION/DATA data1;
.var number_of_biquads;
.SECTION/CODE program;
/*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
3-8
Nth order cascaded biquad filter subroutine
Calling Parameters:
SR1=input X(n)
I0 -> delay line buffer for X(n-2), X(n-1),
Y(n-2), Y(n-1)
L0 = 0
I1 -> scaling factors for each biquad section
L1 = 0 (in the case of a single biquad)
L1 = number of biquad sections
for multiple biquads)
I4 -> scaled biquad coefficients
L4 = 5 x [number of biquads]
M0, M4 = 1
M1 = -3
M2 = 1 (in the case of multiple biquads)
M2 = 0 (in the case of a single biquad)
M3 = (1 - length of delay line buffer)
Return Value:
SR1 = output sample Y(n)
Altered Registers:
SE, MX0, MX1, MY0, MR, SR
Computation Time (with N even):
ADSP-218X: (8 x N/2) + 5 cycles
ADSP-218X: (8 x N/2) + 5 + 5 cycles
All coefficients and data values are assumed to
be in 1.15 format
/
ADSP-218x DSP Instruction Set Reference
Software Examples
.GLOBAL
biquad;
biquad:
CNTR = number_of_biquads;
DO sections UNTIL CE;
/* Loop once for each biquad */
SE=DM(I1,M2);
/* Scale factor for biquad
*/
MX0=DM(I0,M0), MY0=PM(I4,M4);
MR=MX0*MY0(SS), MX1=DM(I0,M0), MY0=PM(I4,M4);
MR=MR+MX1*MY0(SS), MY0=PM(I4,M4);
MR=MR+SR1*MY0(SS), MX0=DM(I0,M0), MY0=PM(I4,M4);
MR=MR+MX0*MY0(SS), MX0=DM(I0,M1), MY0=PM(I4,M4);
DM(I0,M0)=MX1, MR=MR+MX0*MY0(RND);
sections: DM(I0,M0)=SR1, SR=ASHIFT MR1 (HI);
DM(I0,M0)=MX0;
DM(I0,M3)=SR1;
RTS;
Sine Approximation
The following formula approximates the sine of the input variable x (in
radians):
y(x) = sin(x)
= 3.140625(x/π) + 0.02026367(x/π)
2 – 5.325196(x/π)3
4
5
+ 0.5446778(x/π) + 1.800293(x/π)
where:
0
< X < (π/2)
The approximation is a 5th order polynomial fit, accurate for any value of
x from 0° to 90° (the first quadrant). However, because sin(–x) =
-sin(x) and sin(x) = sin(180° – x), you can infer the sine of any angle
from the sine of an angle in the first quadrant.
ADSP-218x DSP Instruction Set Reference
3-9
Sine Approximation
The routine that implements this sine approximation, accurate to within
two LSBs, is shown in Listing 3-3. This routine accepts input values in
1.15 format. The coefficients, which are initialized in data memory in
4.12 format, have been adjusted to reflect an input value scaled to the
maximum range allowed by this format. On this scale, 180° ( π radians)
equals the maximum positive value, 0x7FFF, while –180° ( π radians)
equals the maximum negative value, 0x8000.
The routine shown in Listing 3-3 first adjusts the input angle to its equivalent in the first quadrant. The sine of the modified angle is calculated by
multiplying increasing powers of the angle by the appropriate coefficients.
The result is adjusted if necessary to compensate for the modifications
made to the original input value.
Listing 3-3. Sine Approximation
/*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*/
Sine Approximation
Y = Sin(x)
Calling Parameters
AX0 = x in scaled 1.15 format
M3 = 1
L3 = 0
Return Values
AR = y in 1.15 format
Altered Registers
AY0,AF,AR,MY1,MX1,MF,MR,SR,I3
Computation Time
25 cycles
.SECTION/DATA data1;
.VAR sin_coeff[5] = 0x3240, 0x0053, 0xAACC, 0x08B7, 0x1CCE;
3-10
ADSP-218x DSP Instruction Set Reference
Software Examples
.SECTION/CODE program;
.GLOBAL sin;
sin:
approx:
I3=sin_coeff;
/* Pointer to coeff. buffer
AY0=0x4000;
AR=AX0;
/* Copy x */
AF=AX0 AND AY0;
/* Check 2nd or 4th Quad
IF NE AR = -AX0;
/* If yes, negate
AY0=0x7FFF;
AR=AR AND AY0;
/* Remove sign bit
MY1=AR;
/* Copy x */
MF=AR*MY1 (RND); MX1=DM(I3,M3);
2
/* MF = x , Get 1st coeff
MR=MX1*MY1 (SS); MX1=DM(I3,M3);
/* MR = x * 1st coeff, Get 2nd coeff
CNTR=3;
DO approx UNTIL CE;
MR=MR+MX1*MF (SS);
3
4
5
MF=AR*MF (RND);
/* MF = x , x , x
MX1=DM(I3,M3);
/* Get coeff. C,D,E
MR=MR+MX1*MF (SS);
SR=ASHIFT MR1 BY 3 (HI); /* Convert to 1.15 fmt
SR=SR OR LSHIFT MR0 BY 3 (LO);
AR=PASS SR1;
IF LT AR=PASS AY0;
AF=PASS AX0;
IF LT AR=-AR;
RTS;
*/
*/
*/
*/
*/
*/
*/
*/
*/
/* Saturate if needed
*/
/* Negate output if needed
*/
Single-Precision Matrix Multiply
The routine presented in this section multiplies two input matrices: X and
Y. X is an RxS (R rows, S columns) matrix stored in data memory. Y is an
SxT (S rows, T columns) matrix stored in program memory. The output,
Z, is an RxT (R rows, T columns) matrix written to data memory.
ADSP-218x DSP Instruction Set Reference
3-11
Single-Precision Matrix Multiply
The matrix multiply routine is shown in Listing 3-4. It requires that you
initialize a number of registers as listed in the Calling Parameters section
of the initial comment. SE must contain the value necessary to shift the
result of each multiplication into the desired format. For example, SE
would be set to zero to obtain a matrix of 1.31 values from the multiplication of two matrices of 1.15 values.
Listing 3-4. Single-Precision Matrix Multiply
/*
Single-Precision Matrix Multiplication
*
*
S
Z(i,j) =
*
∑[X(i,k) ×
Y(k,j)] i=0 to R; j=0 to T
k=0
*
*
X is an RxS matrix, Y is an SxT matrix, Z is an RxT matrix
*
* Calling Parameters
*
I1 -> Z buffer in data memory
*
I2 -> X, stored by rows in data memory
L2 = 0
*
I6 -> Y, stored by rows in program memory
L6 = 0
*
M0 = 1 M1 = S
*
M4 = 1 M5 = T
*
L0,L4,L5 = 0
*
SE = Appropriate scale value
*
CNTR = R
*
* Return Values
*
Z Buffer filled by rows
*
* Altered Registers
*
I0,I1,I2,I4,I5,MR,MX0,MY0,SR
*
3-12
ADSP-218x DSP Instruction Set Reference
L1 = 0
Software Examples
* Computation Time
*
((S + 8)
×
T + 4)
×
R + 2 + 2 cycles
*/
.SECTION/CODE program;
.GLOBAL spmm;
spmm:
DO row_loop UNTIL CE;
I5=I6;/* I5 = start of Y */
CNTR=M5;
DO column_loop UNTIL CE;
I0=I2;
/* Set I0 to current X row */
I4=I5;
/* Set I4 to current Y col */
CNTR=M1;
MR=0, MX0=DM(I0,M0), MY0=PM(I4,M5)
/* Get 1st data */
DO element_loop UNTIL CE;
element_loop:
MR=MR+MX0*MY0 (SS), MX0=DM(I0,M0),
MY0=PM(I4,M5);
SR=ASHIFT MR1 (HI), MY0=DM(I5,M4); /* Update I5 */
SR=SR OR LSHIFT MR0 (LO);
/* Finish Shift */
column_loop:
DM(I1,M0)=SR1;
/* Save Output
row_loop:
MODIFY(I2,M1);
*/
/* Update I2 to next X row */
RTS;
Radix-2 Decimation-in-Time FFT
The FFT program includes three subroutines. The first subroutine scrambles the input data placing the data in bit-reversed address order, so that
the FFT output is in the normal, sequential order. The next subroutine
computes the FFT. The third subroutine scales the output data to maintain the block floating-point data format.
ADSP-218x DSP Instruction Set Reference
3-13
Radix-2 Decimation-in-Time FFT
The program is contained in four modules. The main module declares and
initializes data buffers and calls subroutines. The other three modules contain the FFT, bit reversal, and block floating-point scaling subroutines.
The main module calls the FFT and bit reversal subroutines. The FFT
module calls the data scaling subroutine.
The FFT is performed in place; that is, the outputs are written to the same
buffer that the inputs are read from.
Main Module
The dit_fft_main module is shown in Listing 3-5. N is the number of
points in the FFT (in this example, N=1024) and N_div_2 is used for specifying the lengths of buffers. To change the number of points in the FFT,
you change the value of these constants and the twiddle factors.
The data buffers twid_real and twid_imag in program memory hold the
twiddle factor cosine and sine values. The inplacereal, inplaceimag,
inputreal and inputimag buffers in data memory store real and imaginary
data values. Sequentially ordered input data is stored in inputreal and
inputimag. This data is scrambled and written to inplacereal and inplaceimag. A four-location buffer called “padding” is placed at the end of
inplaceimag to allow data accesses to exceed the buffer length. This buffer
assists in debugging but is not necessary in a real system. Variables
(one-location buffers) named groups, bflys_per_group, node_space and
blk_exponent are declared last.
The real parts (cosine values) of the twiddle factors are stored in the buffer
twid_real. This buffer is initialized from the file twid_real.dat. Likewise, twid_imag.dat values initialize the twid_imag buffer that stores the
sine values of the twiddle factors. In an actual system, the hardware would
be set up to initialize these memory locations.
3-14
ADSP-218x DSP Instruction Set Reference
Software Examples
The variable called groups is initialized to N_div_2. The variables
bflys_per_group and node_space are each initialized to 2 because there
are two butterflies per group in the second stage of the FFT. The
blk_exponent variable is initialized to zero. This exponent value is
updated when the output data is scaled.
After the initializations are complete, two subroutines are called. The first
subroutine places the input sequence in bit-reversed order. The second
performs the FFT and calls the block floating-point scaling routine.
Listing 3-5. Main Module, Radix-2 DIT FFT
.SECTION/CODE
#define N
#define N_div_2
program;
1024
512
.SECTION/DATA
data1;
.VAR
padding [4]=0,0,0,0;
.VAR
.VAR
.GLOBAL
inputreal [N] = "inputreal.dat";
inputimag [N] = "inputimag.dat";
inputreal, inputimag;
.VAR
.VAR
.GLOBAL
inplacereal[N];
inplaceimag[N] = "inputimag.dat";
inplacereal, inplaceimag;
.VAR
.VAR
.VAR
.VAR
.GLOBAL
groups = N_div_2;
bflys_per_group = 2;
node_space = 2;
blk_exponent = 0;
groups, bflys_per_group, node_space, blk_exponent;
.SECTION/DATA
data2;
.VAR
.VAR
twid_real [N_div_2]
twid_imag [N_div_2]
/* For 2048 points */
= "twid_real.dat";
= "twid_imag.dat";
ADSP-218x DSP Instruction Set Reference
3-15
Radix-2 Decimation-in-Time FFT
.GLOBAL
twid_real, twid_imag;
.SECTION/CODE
program;
.EXTERN
scramble, fft_strt;
CALL scramble;
CALL fft_strt;
IDLE;
/* subroutine calls */
/* halt program
*/
DIT FFT Subroutine
The radix-2 DIT FFT routine is shown in Listing 3-6. The constants N
and log2N are the number of points and the number of stages in the FFT,
respectively. To change the number of points in the FFT, you modify
these constants.
The first and last stages of the FFT are performed outside of the loop that
executes all the other stages. Treating the first and last stages individually
allows them to execute faster. In the first stage, there is only one butterfly
per group, so the butterfly loop is unnecessary. The twiddle factors are all
either 1 or 0 making multiplications unnecessary. In the last stage, there is
only one group. Therefore, the group loop is unnecessary and the setup
operations for the next stage.
Listing 3-6. Radix-2 DIT FFT Routine, Conditional Block Floating-Point
/* 1024 point DIT radix 2 FFT
* Block Floating Point Scaling */
.SECTION/CODE
/*
*
*
*
*
*
3-16
program;
Calling Parameters
inplacereal=real input data in scrambled order
inplaceimag=all zeroes (real input assumed)
twid_real=twiddle factor cosine values
twid_imag=twiddle factor sine values
groups=N/2
ADSP-218x DSP Instruction Set Reference
Software Examples
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*/
bflys_per_group=1
node_space=1
Return Values
inplacereal=real FFT results, sequential order
inplaceimag=imag. FFT results, sequential order
Altered Registers
I0,I1,I2,I3,I4,I5,L0,L1,L2,L3,L4,L5
M0,M1,M2,M3,M4,M5
AX0,AX1,AY0,AY1,AR,AF
MX0,MX1,MY0,MY1,MR,SB,SE,SR,SI
Altered Memory
inplacereal, inplaceimag, groups, node_space,
bflys_per_group, blk_exponent
#define
#define
#define
#define
log2N
N
nover2
nover4
10
1024
512
256
.EXTERN
.EXTERN
.EXTERN
.EXTERN
.GLOBAL
twid_real, twid_imag;
inplacereal, inplaceimag;
groups, bflys_per_group, node_space;
bfp_adj;
fft_strt;
fft_strt:
CNTR=log2N - 2;
/* Initialize stage counter */
M0=0;
M1=1;
L1=0;
L2=0;
L3=0;
L4=LENGTH(twid_real);
L5=LENGTH(twid_imag);
L6=0;
SB=-2;
ADSP-218x DSP Instruction Set Reference
3-17
Radix-2 Decimation-in-Time FFT
/* ---- STAGE 1 ---- */
I0=inplacereal;
I1=inplacereal + 1;
I2=inplaceimag;
I3=inplaceimag + 1;
M2=2;
CNTR=nover2;
AX0=DM(I0,M0);
AY0=DM(I1,M0);
AY1=DM(I3,M0);
group_lp:
DO group_lp UNTIL CE;
AR=AX0+AY0, AX1=DM(I2,M0);
SB=EXPADJ AR, DM(I0,M2)=AR;
AR=AX0-AY0;
SB=EXPADJ AR;
DM(I1,M2)=AR, AR=AX1+AY1;
SB=EXPADJ AR, DM(I2,M2)=AR;
AR=AX1-AY1, AX0=DM(I0,M0);
SB=EXPADJ AR, DM(I3,M2)=AR;
AY0=DM(I1,M0);
AY1=DM(I3,M0);
CALL bfp_adj;
/* ----- STAGES 2 TO N-1----- */
DO stage_loop UNTIL CE;
/*
I0=inplacereal;
/*
I2=inplaceimag;
/*
SI=DM(groups);
SR=ASHIFT SI BY -1(LO);
DM(groups)=SR0;
CNTR=SR0;
M4=SR0;
/*
M2=DM(node_space);
/*
I1=I0;
MODIFY(I1,M2);
/*
3-18
Compute all stages in FFT
*/
I0 ->x0 in 1st grp of stage */
I2 ->y0 in 1st grp of stage */
/* groups / 2
*/
/* groups=groups / 2 */
/* CNTR=group counter */
M4=twiddle factor modifier */
M2=node space modifier
*/
I1 ->y0 of 1st grp in stage */
ADSP-218x DSP Instruction Set Reference
Software Examples
MODIFY(I3,M2);
/* I3 ->y1 of 1st grp in stage */
DO group_loop UNTIL CE;
I4=twid_real;
I5=twid_imag;
CNTR=DM(bflys_per_group);
MY0=PM(I4,M4),MX0=DM(I1,M0);
MY1=PM(I5,M4),MX1=DM(I3,M0);
DO bfly_loop UNTIL CE;
MR=MX0*MY1(SS),AX0=DM(I0,M0);
bfly_loop:
/*
/*
/*
/*
/*
I4 -> C of W0
*/
I5 -> (-S) of W0 */
CNTR=bfly count */
MY0=C,MX0=x1
*/
MY1=-S,MX1=y1
*/
/* MR=x1(-S),AX0=x0 */
MR=MR+MX1*MY0(RND),AX1=DM(I2,M0);
/* MR=(y1(C)+x1(-S)),AX1=y0 */
AY1=MR1,MR=MX0*MY0(SS);
/* AY1=y1(C)+x1(-S),MR=x1(C) */
MR=MR-MX1*MY1(RND);
/* MR=x1(C)-y1(-S)
*/
AY0=MR1,AR=AX1-AY1;
/* AY0=x1(C)-y1(-S), */
/* AR=y0-[y1(C)+x1(-S)] */
SB=EXPADJ AR,DM(I3,M1)=AR;
/* Check for bit growth, */
/* y1=y0-[y1(C)+x1(-S)] */
AR=AX0-AY0,MX1=DM(I3,M0),MY1=PM(I5,M4);
/* AR=x0-[x1(C)-y1(-S)],
*/
/* MX1=next y1,MY1=next (-S) */
SB=EXPADJ AR,DM(I1,M1)=AR;
/* Check for bit growth, */
/* x1=x0-[x1(C)-y1(-S)] */
AR=AX0+AY0,MX0=DM(I1,M0),MY0=PM(I4,M4);
/* AR=x0+[x1(C)-y1(-S)], */
/* MX0=next x1,MY0=next C */
SB=EXPADJ AR,DM(I0,M1)=AR;
/* Check for bit growth, */
/* x0=x0+[x1(C)-y1(-S)] */
AR=AX1+AY1;
/* AR=y0+[y1(C)+x1(-S)] */
SB=EXPADJ AR,DM(I2,M1)=AR;
/* Check for bit growth, */
/* y0=y0+[y1(C)+x1(-S)] */
MODIFY(I0,M2);
/* I0 ->1st x0 in next group */
MODIFY(I1,M2);
/* I1 ->1st x1 in next group */
MODIFY(I2,M2);
/* I2 ->1st y0 in next group */
ADSP-218x DSP Instruction Set Reference
3-19
Radix-2 Decimation-in-Time FFT
group_loop: MODIFY(I3,M2);
/* I3 ->1st y1 in next group */
CALL bfp_adj;
/* Compensate for bit growth */
SI=DM(bflys_per_group);
SR=ASHIFT SI BY 1(LO);
DM(node_space)=SR0;
/* node_space=node_space / 2 */
stage_loop: DM(bflys_per_group)=SR0;
/* bflys_per_group=bflys_per_group / 2 */
/* ---- LAST STAGE ---- */
I0=inplacereal;
I1=inplacereal+nover2;
I2=inplaceimag;
I3=inplaceimag+nover2;
CNTR=nover2;
M2=DM(node_space);
M4=1;
I4=twid_real;
I5=twid_imag;
MY0=PM(I4,M4),MX0=DM(I1,M0);
MY1=PM(I5,M4),MX1=DM(I3,M0);
DO bfly_lp UNTIL CE;
MR=MX0*MY1(SS),AX0=DM(I0,M0);
/* MY0=C,MX0=x1 */
/* MY1=-S,MX1=y1 */
/* MR=x1(-S),AX0=x0 */
MR=MR+MX1*MY0(RND),AX1=DM(I2,M0);
/* MR=(y1(C)+x1(-S)),AX1=y0 */
AY1=MR1,MR=MX0*MY0(SS);
/* AY1=y1(C)+x1(-S),MR=x1(C) */
MR=MR-MX1*MY1(RND);
/* MR=x1(C)-y1(-S) */
AY0=MR1,AR=AX1-AY1;
/* AY0=x1(C)-y1(-S), */
/* AR=y0-[y1(C)+x1(-S)] */
SB=EXPADJ AR,DM(I3,M1)=AR;
/* Check for bit growth, */
/* y1=y0-[y1(C)+x1(-S)] */
AR=AX0-AY0,MX1=DM(I3,M0),MY1=PM(I5,M4);
/* AR=x0-[x1(C)-y1(-S)],
*/
3-20
ADSP-218x DSP Instruction Set Reference
Software Examples
bfly_lp:
/* MX1=next y1,MY1=next (-S) */
SB=EXPADJ AR,DM(I1,M1)=AR;
/* Check for bit growth, */
/* x1=x0-[x1(C)-y1(-S)] */
AR=AX0+AY0,MX0=DM(I1,M0),MY0=PM(I4,M4);
/* AR=x0+[x1(C)-y1(-S)], */
/* MX0=next x1,MY0=next C */
SB=EXPADJ AR,DM(I0,M1)=AR;
/* Check for bit growth, */
/* x0=x0+[x1(C)-y1(-S)] */
AR=AX1+AY1;
/* AR=y0+[y1(C)+x1(-S)] */
SB=EXPADJ AR,DM(I2,M1)=AR;
/* Check for bit growth */
CALL bfp_adj;
RTS;
Bit-Reverse Subroutine
The bit-reversal routine, called scramble, puts the input data in
bit-reversed order so that the results are in sequential order. This routine
(Listing 3-7) uses the bit-reverse capability of the ADSP-218x processors.
Listing 3-7. Bit-Reverse Routine (Scramble)
.SECTION/CODE program;
/* Calling Parameters
*
Sequentially ordered input data in inputreal
*
* Return Values
*
Scrambled input data in inplacereal
*
* Altered Registers
*
I0,I4,M0,M4,AY1
*
ADSP-218x DSP Instruction Set Reference
3-21
Radix-2 Decimation-in-Time FFT
* Altered Memory
*
*/
inplacereal
#define
#define
N
mod_value
1024
0x0010;
.EXTERN
inputreal, inplacereal;
.GLOBAL
scramble;
/* Initialize constants */
scramble: I4=inputreal;
/* I4->sequentially ordered data */
I0=inplacereal;
/* I0->scrambled data
*/
M4=1;
M0=mod_value;
/* M0=modifier for reversing N Bits */
L4=0;
L0=0;
CNTR = N;
brev:
ENA BIT_REV; /* Enable bit-reversed outputs on DAG1
DO brev UNTIL CE;
AY1=DM(I4,M4); /* Read sequentially ordered data
DM(I0,M0)=AY1;
/* Write data in bit-reversed location
DIS BIT_REV;
/* Disable bit-reverse
RTS;
/* Return to calling program
*/
*/
*/
*/
*/
Block Floating-Point Scaling Subroutine
The bfp_adj routine checks the FFT output data for bit growth and scales
the entire set of data if necessary. This check prevents data overflow for
each stage in the FFT. The routine, shown in Listing 3-8, uses the exponent detection capability of the shifter.
3-22
ADSP-218x DSP Instruction Set Reference
Software Examples
Listing 3-8. Radix-2 Block Floating-Point Scaling Routine
.SECTION/CODE program;
/* Calling Parameters
* Radix-2 DIT FFT stage results in inplacereal and inplaceimag
*
* Return Parameters
* inplacereal and inplaceimag adjusted for bit growth
*
* Altered Registers
* I0,I1,AX0,AY0,AR,MX0,MY0,MR,CNTR
*
* Altered Memory
* inplacereal, inplaceimag, blk_exponent
*/
#define
Ntimes
2048
.EXTERN
inplacereal, blk_exponent;
/* Begin declaration */
.GLOBAL
bfp_adj;
bfp_adj:
AY0=CNTR;
AR=AY0-1;
IF EQ RTS;
AY0=-2;
AX0=SB;
AR=AX0-AY0;
IF EQ RTS;
/* Check for last stage */
/* If last stage, return */
I0=inplacereal;
I1=inplacereal;
AY0=-1;
MY0=0x4000;
/*
/*
/*
/*
/*
Check for SB=-2
IF SB=-2, no bit
growth, return
I0=read pointer
I1=write pointer
*/
*/
*/
*/
*/
/* Set MY0 to shift 1 */
/* bit right
*/
AR=AX0-AY0,MX0=DM(I0,M1);
/* Check if SB=-1 */
ADSP-218x DSP Instruction Set Reference
3-23
Radix-2 Decimation-in-Time FFT
/* Get 1st sample */
IF EQ JUMP strt_shift;
strt_shift:
shift_loop:
/* If SB=-1, shift block
*/
/* data 1 bit
*/
AX0=-2;
/* Set AX0 for block
*/
/* exponent update
*/
MY0=0x2000;
/* Set MY0 to shift 2
*/
/* bits right
*/
CNTR=Ntimes2 - 1;
/* initialize loop counter */
DO shift_loop UNTIL CE;
/* Shift block of data*/
MR=MX0*MY0(RND),MX0=DM(I0,M1);
/* MR=shifted data */
/* MX0=next value */
DM(I1,M1)=MR1;
/* Unshifted data */
/* shifted data */
MR=MX0*MY0(RND);
/* Shift last data word */
AY0=DM(blk_exponent); /* Update block exponent */
/*and store last shifted sample */
DM(I1,M1)=MR1,AR=AY0-AX0;
DM(blk_exponent)=AR;
RTS;
3-24
ADSP-218x DSP Instruction Set Reference
4 INSTRUCTION SET
This chapter is a complete reference for the instruction set of the
ADSP-218x DSPs.
The chapter contains:
• “Quick List Of Instructions” on page 4-2
• “Instruction Set Overview” on page 4-5
• “Multifunction Instructions” on page 4-7
• “ALU, MAC and Shifter Instructions” on page 4-14
• “MOVE: Read and Write Instructions” on page 4-20
• “Program Flow Control” on page 4-22
• “Miscellaneous Instructions” on page 4-25
• “Extra Cycle Conditions” on page 4-27
• “Instruction Set Syntax” on page 4-28
• “ALU Instructions” on page 4-31
• “MAC Instructions” on page 4-72
• “Shifter Instructions” on page 4-94
• “Move Instructions” on page 4-113
• “Program Flow Instructions” on page 4-133
• “MISC Instructions” on page 4-151
• “Multifunction Instructions” on page 4-171
ADSP-218x DSP Instruction Set Reference
4-1
Quick List Of Instructions
Quick List Of Instructions
The instruction set is organized by instruction group and, within each
group, by individual instruction. The list below shows all of the instructions and the reference page for each instruction.
ALU Instructions
• “Add/Add With Carry” on page 4-32
• “Subtract X-Y/Subtract X-Y With Borrow” on page 4-35
• “Subtract Y-X/Subtract Y-X With Borrow” on page 4-39
• “Bitwise Logic: AND, OR, XOR” on page 4-42
• “Bit Manipulation: TSTBIT, SETBIT, CLRBIT, TGLBIT” on
page 4-45
• “Clear: PASS” on page 4-48
• “Syntax” on page 4-32
• “NOT” on page 4-54
• “Absolute Value: ABS” on page 4-56
• “Increment” on page 4-58
• “Decrement” on page 4-60
• “Divide Primitives: DIVS and DIVQ” on page 4-62
• “Generate ALU Status Only: NONE” on page 4-70
MAC Instructions
• “Multiply” on page 4-73
• “Multiply With Cumulative Add” on page 4-77
• “Multiply With Cumulative Subtract” on page 4-81
4-2
ADSP-218x DSP Instruction Set Reference
Instruction Set
• “Squaring” on page 4-85
• “MAC Clear” on page 4-88
• “MAC Transfer MR” on page 4-90
• “Conditional MR Saturation” on page 4-92
Shifter Instructions
• “Arithmetic Shift” on page 4-95
• “Logical Shift” on page 4-98
• “Normalize” on page 4-101
• “Derive Exponent” on page 4-104
• “Block Exponent Adjust” on page 4-107
• “Arithmetic Shift Immediate” on page 4-109
• “Logical Shift Immediate” on page 4-111
Move Instructions
• “Register Move” on page 4-114
• “Load Register Immediate” on page 4-116
• “Data Memory Read (Direct Address)” on page 4-118
• “Data Memory Read (Indirect Address)” on page 4-120
• “Program Memory Read (Indirect Address)” on page 4-122
• “Data Memory Write (Direct Address)” on page 4-124
• “Data Memory Read (Indirect Address)” on page 4-120
• “Program Memory Write (Indirect Address)” on page 4-129
• “IO Space Read/Write” on page 4-131
ADSP-218x DSP Instruction Set Reference
4-3
Quick List Of Instructions
Program Flow Instructions
• “JUMP” on page 4-134
• “CALL” on page 4-136
• “JUMP or CALL on Flag In Pin” on page 4-138
• “Modify Flag Out Pin” on page 4-140
• “RTS (Return from Subroutine)” on page 4-142
• “RTI (Return from Interrupt)” on page 4-144
• “Do Until” on page 4-146
• “Idle” on page 4-149
MISC Instructions
• “Stack Control” on page 4-152
• “Program Memory Overlay Register Update” on page 4-162
• “Data Memory Overlay Register Update” on page 4-165
• “Modify Address Register” on page 4-168
• “No Operation” on page 4-170
Multifunction Instructions
• “Computation With Memory Read” on page 4-172
• “Computation With Register-to-Register Move” on page 4-178
• “Computation With Memory Write” on page 4-183
• “Data and Program Memory Read” on page 4-188
• “ALU/MAC With Data and Program Memory Read” on
page 4-190
4-4
ADSP-218x DSP Instruction Set Reference
Instruction Set
Instruction Set Overview
This chapter provides an overview and detailed reference for the instruction set of the ADSP-218x DSPs. The instruction set is grouped into the
following categories:
• Computational: ALU, MAC, Shifter
• Move
• Program Flow
• Multifunction
• Miscellaneous
The instruction set is tailored to the computation-intensive algorithms
common in DSP applications. For example, sustained single-cycle multiplication/accumulation operations are possible. The instruction set
provides full control of the processors’ three computational units: the
ALU, MAC and Shifter. Arithmetic instructions can process single-precision 16-bit operands directly; provisions for multiprecision operations are
available.
The high-level syntax of ADSP-218x source code is both readable and efficient. Unlike many assembly languages, the ADSP-218x instruction set
uses an algebraic notation for arithmetic operations and for data moves,
resulting in highly readable source code. There is no performance penalty
for this; each program statement assembles into one 24-bit instruction
which executes in a single cycle. There are no multicycle instructions in
the instruction set. (If memory access times require, or contention for
off-chip memory occurs, overhead cycles are required, but all instructions
can otherwise execute in a single cycle.)
ADSP-218x DSP Instruction Set Reference
4-5
Instruction Set Overview
In addition to JUMP and CALL, the instruction set’s control instructions
support conditional execution of most calculations and a DO UNTIL looping instruction. Return from interrupt (RTI) and return from subroutine
(RTS) are also provided.
The IDLE instruction is provided for idling the processor until an interrupt
occurs. IDLE puts the processor into a low-power state while waiting for
interrupts.
Two addressing modes are supported for memory fetches. Direct addressing uses immediate address values; indirect addressing uses the I registers
of the two data address generators (DAGs).
The 24-bit instruction word allows a high degree of parallelism in performing operations. The instruction set allows for single-cycle execution
of any of the following combinations:
• Any ALU, MAC or Shifter operation (conditional or
non-conditional)
• Any register-to-register move
• Any data memory read or write
• A computation with any data register to data register move
• A computation with any memory read or write
• A computation with a read from two memories
The instruction set allows maximum flexibility. It provides moves from
any register to any other register, and from most registers to/from memory. In addition, almost any ALU, MAC or Shifter operation may be
combined with any register-to-register move or with a register move to or
from internal or external memory.
4-6
ADSP-218x DSP Instruction Set Reference
Instruction Set
Because the multifunction instructions best illustrate the power of the
processors’ architecture, in the next section we begin with a discussion of
this group of instructions.
Multifunction Instructions
Multifunction operations take advantage of the inherent parallelism of the
ADSP-218x architecture by providing combinations of data moves, memory reads/memory writes, and computation, all in a single cycle.
ALU/MAC With Data and Program Memory Read
Perhaps the single most common operation in DSP algorithms is the sum
of products, performed as follows:
• Fetch two operands (such as a coefficient and data point)
• Multiply the operands and sum the result with previous products
The ADSP-218x processors can execute both data fetches and the multiplication/accumulation in a single-cycle. Typically, a loop of
multiply/accumulates can be expressed in ADSP-218x source code in just
two program lines. Since the on-chip program memory of the ADSP-218x
processors is fast enough to provide an operand and the next instruction in
a single cycle, loops of this type can execute with sustained single-cycle
throughput. An example of such an instruction is:
MR=MR+MX0*MY0(SS), MX0=DM(I0,M0), MY0=PM(I4,M5);
The first clause of this instruction (up to the first comma) says that MR, the
MAC result register, gets the sum of its previous value plus the product of
the (current) X and Y input registers of the MAC (MX0 and MY0) both
treated as signed (SS).
ADSP-218x DSP Instruction Set Reference
4-7
Multifunction Instructions
In the second and third clauses of this multifunction instruction, two new
operands are fetched. One is fetched from the data memory (DM) pointed
to by index register zero (I0, post modified by the value in M0) and the
other is fetched from the program memory location (PM) pointed to by I4
(post-modified by M5 in this instance). Note that indirect memory addressing uses a syntax similar to array indexing, with DAG registers providing
the index values. Any I register may be paired with any M register within
the same DAG.
As discussed in the ADSP-218x DSP Hardware Reference Manual, Chapter
2, “Computational Units”, registers are read at the beginning of the cycle
and written at the end of the cycle. The operands present in the MX0 and
MY0 registers at the beginning of the instruction cycle are multiplied and
added to the MAC result register, MR. The new operands fetched at the
end of this same instruction overwrite the old operands after the multiplication has taken place and are available for computation on the following
cycle. You may, of course, load any data registers in conjunction with the
computation, not just MAC registers with a MAC operation as in our
example.
The computational part of this multifunction instruction may be any
unconditional ALU instruction except division or any MAC instruction
except saturation. Certain other restrictions apply: the next X operand
must be loaded into MX0 from data memory and the new Y operand must
be loaded into MY0 from program memory (internal and external memory
are identical at the level of the instruction set). The result of the computation must go to the result register (MR or AR) not to the feedback register
(MF or AF).
4-8
ADSP-218x DSP Instruction Set Reference
Instruction Set
Data and Program Memory Read
This variation of a multifunction instruction is a special case of the multifunction instruction described above in which the computation is
omitted. It executes only the dual operand fetch, as shown below:
AX0=DM(I2,M0), AY0=PM(I4,M6);
In this example we have used the ALU input registers as the destination.
As with the previous multifunction instruction, X operands must come
from data memory and Y operands from program memory (internal or
external memory in either case, for the processors with on-chip memory).
Computation With Memory Read
If a single memory read is performed instead of the dual memory read of
the previous two multifunction instructions, a wider range of computations can be executed. The legal computations include all ALU operations
except division, all MAC operations and all Shifter operations except
SHIFT IMMEDIATE. Computation must be unconditional. An example of
this kind of multifunction instruction is:
AR=AX0+AY0, DM(I0,M0)=AX0;
Here, an addition is performed in the ALU while a single operand is
fetched from data memory. The restrictions are similar to those for previous multifunction instructions. The value of AX0, used as a source for the
computation, is the value at the beginning of the cycle. The data read
operation loads a new value into AX0 by the end of the cycle. For this same
reason, the destination register (AR in the example above) cannot be the
destination for the memory read.
ADSP-218x DSP Instruction Set Reference
4-9
Multifunction Instructions
Computation With Memory Write
The computation with memory write instruction is similar in structure to
the computation with memory read: the order of the clauses in the
instruction line, however, is reversed. First the memory write is performed, then the computation, as shown below:
DM(I0,M0)=AR, AR=AX0+AY0;
Again the value of the source register for the memory write (AR in this
example) is the value at the beginning of the instruction. The computation loads a new value into the same register; this is the value in AR at the
end of this instruction. Reversing the order of the clauses would imply
that the result of the computation is written to memory when, in fact, the
previous value of the register is what is written. There is no requirement
that the same register be used in this way although this usually is the case
in order to pipeline operands to the computation.
The restrictions on computation operations are identical to those given
above. All ALU operations except division, all MAC operations, and all
Shifter operations except SHIFT IMMEDIATE are legal. Computations must
be unconditional.
Computation With Data Register Move
This final type of multifunction instruction performs a data register to
data register move in parallel with a computation. Most of the restrictions
applying to the previous two instructions also apply to this instruction.
AR=AX0+AY0, AX0=MR2;
Here, an ALU addition operation occurs while a new value is loaded into
AX0 from MR2. As before, the value of AX0 at the beginning of the instruction is the value used in the computation. The move may be from or to all
ALU, MAC and Shifter input and output registers except the feedback
registers (AF and MF) and SB.
4-10
ADSP-218x DSP Instruction Set Reference
Instruction Set
In the example, the data register move loads the AX0 register with the new
value at the end of the cycle. All ALU operations except division, all MAC
operations and all Shifter operations except SHIFT IMMEDIATE are legal.
Computation must be unconditional.
A complete list of data registers is given in “Processor Registers: reg and
dreg” on page 4-22. A complete list of the permissible xops and yops for
computational operations is given in the reference page for each instruction. Table 4-1 shows the legal combinations for multifunction
instructions (described in Table 4-2). You may combine operations on the
same row with each other.
Table 4-1. Summary of Valid Combinations for Multifunction
Instructions
Unconditional Computations
Data Move
(DM=DAG1)
Data Move
(PM=DAG2)
None or any ALU (except Division) or MAC
DM read
PM read
Any MAC
Any ALU except Division
Any Shift except Immediate
DM read
—
DM write
—
Register-to-Register
—
PM read
—
PM write
ADSP-218x DSP Instruction Set Reference
4-11
Multifunction Instructions
Table 4-2. Multifunction Instructions
<ALU>*†
,
AX0
=
DM (
I0
,
M0
),
AY0
=
PM (
I4
,
M4
),
<MAC>*†
AX0
I1
,
M1
AY1
I5
,
M5
MX0
I2
,
M2
MY0
I6
,
M6
MX1
I3
,
M3
MY1
I7
,
M7
I0
,
M0
AX1
I1
,
M1
AY1
MX0
I2
,
M2
MY0
I6
,
M6
MX1
I3
,
M3
MY1
I7
,
M7
<ALU>*
=
AX1
DM (
, dreg =
DM (
) ,
AY0
=
I0
,
M0
<MAC>*
I1
,
M1
<SHIFT>*
I2
,
M2
I3
,
M3
I4
,
M4
I5
,
M5
I6
,
M6
I7
,
M7
PM (
I4
,
M4
I5
,
M5
I6
,
M6
I7
,
M7
PM (
)
I4
,
M4
I5
,
M5
;
)
* May not be conditional instruction
4-12
ADSP-218x DSP Instruction Set Reference
);
Instruction Set
DM (
PM (
I0
,
M0
I1
,
M1
<MAC>*
I2
,
M2
<SHIFT>*
I3
,
M3
I4
,
M4
I5
,
M5
I6
,
M6
I7
,
M7
I4
,
M4
I5
,
M5
I6
,
M6
I7
,
M7
<ALU>*
)
= dreg,
<ALU>*
;
)
, dreg = dreg;
<MAC>*
<SHIFT>*
<ALU>
Any ALU instructions (except DIVS, DIVQ)
<MAC>
Any multiply/accumulate instruction
<SHIFT>
Any shifter instruction (except Shift Immediate)
* May not be conditional instruction
† AR, MR result registers must be used-- not AF, MF feedback registers
or NONE.
SEE ALSO:
• “ALU/MAC With Data and Program Memory Read” on
page 4-190
ADSP-218x DSP Instruction Set Reference
4-13
ALU, MAC and Shifter Instructions
ALU, MAC and Shifter Instructions
This group of instructions performs computations. All of these instructions can be executed conditionally except the ALU division instructions
and the Shifter SHIFT IMMEDIATE instructions.
ALU Group
The following is an example of one ALU instruction, Add/Add with
Carry:
IF AC AR=AX0+AY0+C;
The (optional) conditional expression, IF AC, tests the ALU Carry bit
(AC); if there is a carry from the previous instruction, this instruction executes, otherwise a NOP occurs and execution continues with the next
instruction. The algebraic expression AR=AX0+AY0+C means that the ALU
result register (AR) gets the value of the ALU X input and Y input registers
plus the value of the carry-in bit.
Table 4-3 gives a summary list of all ALU instructions. In this list, condition stands for all the possible conditions that can be tested and xop and
yop stand for the registers that can be specified as input for the ALU. The
conditional clause is optional and is enclosed in square brackets to show
this. A complete list of the permissible xops and yops is given in the reference page for each instruction.
A complete list of conditions is given in Table 4-9 on page 4-24.
4-14
ADSP-218x DSP Instruction Set Reference
Instruction Set
Table 4-3. ALU Instructions
[IF cond]
AR
= xop
+ yop
AF
;
+ C
+ yop + C
+ constant
+ constant + C
[IF cond]
AR
= xop
– yop
AF
;
– yop + C – 1
+ C – 1
–
–1
[IF cond]
AR
=
–
AF
[IF cond]
AR
AR
constant + C
– 1
;
yop
= NOT
AF
[IF cond]
xop
constant
xop
;
yop
= ABS
xop;
= yop
+ 1;
= yop
– 1;
AF
[IF cond]
AR
AF
[IF cond]
AR
AF
DIVS yop, xop ;
DIVQ xop ;
NONE = <ALU> ;
ADSP-218x DSP Instruction Set Reference
4-15
ALU, MAC and Shifter Instructions
[IF cond]
AR
=
yop
– xop
AF
;
– xop + C – 1
– xop + C – 1
– xop + constant
– xop + constant + C –1
[IF cond]
AR
= xop
AF
AND
yop
OR
constant
;
XOR
[IF cond]
AR
=
AF
TSTBIT n OF xop
;
SETBIT n OF xop
CLRBIT n OF xop
TGLBIT n OF xop
[IF cond]
AR
= PASS
AF
xop
;
yop
constant
MAC Group
Here is an example of one of the MAC instructions,
Multiply/Accumulate:
IF NOT MV MR=MR+MX0*MY0(UU);
The conditional expression, IF NOT MV, tests the MAC overflow bit. If the
condition is not true, a NOP is executed. The expression MR=MR+MX0*MY0 is
the multiply/accumulate operation: the multiplier result register (MR) gets
the value of itself plus the product of the X and Y input registers selected.
The modifier in parentheses (UU) treats the operands as unsigned. There
4-16
ADSP-218x DSP Instruction Set Reference
Instruction Set
can be only one such modifier selected from the available set. The modifier (SS) means both are signed, while (US) and (SU) mean that either the
first or second operand is signed; (RND) means to round the (implicitly
signed) result.
Table 4-4 gives a summary list of all MAC instructions. In this list,
condition stands for all the possible conditions that can be tested and xop
and yop stand for the registers that can be specified as input for the MAC.
A complete list of the permissible xops and yops is given in the reference
page for each instructions.
Table 4-4. MAC Instructions
[IF cond]
MR
= xop
*
MF
yop
(
xop
SS
);
SU
US
UU
RND
[IF cond]
MR
= MR + xop *
MF
yop
(
xop
SS
);
SU
US
UU
RND
[IF cond]
MR
MF
= MR – xop *
yop
xop
(
SS
);
SU
US
UU
RND
ADSP-218x DSP Instruction Set Reference
4-17
ALU, MAC and Shifter Instructions
Table 4-4. MAC Instructions (Cont’d)
[IF cond]
MR
= 0;
MF
[IF cond]
MR
= MR [(RND)];
MF
IF MV SAT MR ;
Shifter Group
Here is an example of one of the Shifter instruction, Normalize:
IF NOT CE SR= SR OR NORM SI (HI);
The conditional expression, IF NOT CE, tests the “not counter expired”
condition. If the condition is false, a NOP is executed. The destination of
all shifting operations is the Shifter Result register, SR. The destination of
exponent detection instructions is SE or SB, as shown in Table 4-5. In this
example, SI, the Shifter Input register, is the operand. The amount and
direction of the shift is controlled by the signed value in the SE register in
all shift operations except an immediate shift. Positive values cause left
shifts; negative values cause right shifts.
The optional SR OR modifier logically ORs the result with the current contents of the SR register; this allows you to construct a 32-bit value in SR
from two 16-bit pieces. NORM is the operator and HI is the modifier that
determines whether the shift is relative to the HI or LO (16-bit) half of SR.
If SR OR is omitted, the result is passed directly into SR.
Table 4-5 gives a summary list of all Shifter instructions. In this list, condition stands for all the possible conditions that can be tested.
4-18
ADSP-218x DSP Instruction Set Reference
Instruction Set
Table 4-5. Shifter Instructions
[IF cond]
SR
=
[SR OR] ASHIFT xop
(
HI
);
LO
[IF cond]
SR
=
[SR OR] LSHIFT xop
(
HI
);
LO
[IF cond] SR
=
[SR OR] NORM xop
(
HI
);
LO
[IF cond] SE
=
EXP xop
(
HI
);
LO
HIX
[IF cond] SB
=
SR = [SR OR] ASHIFT xop BY <exp>
EXPADJ xop;
(
HI
);
LO
SR = [SR OR] LSHIFT xop BY <exp>
(
HI
);
LO
ADSP-218x DSP Instruction Set Reference
4-19
MOVE: Read and Write Instructions
MOVE: Read and Write Instructions
Move instructions, shown in Table 4-6, move data to and from data registers and external memory. Registers are divided into two groups, referred
to as reg which includes almost all registers and dreg, or data registers,
which is a subset. Only the program counter (PC) and the ALU and MAC
feedback registers (AF and MF) are not accessible.
Table 4-6. Move Instructions
reg = reg ;
reg = DM (<address>) ;
(
dreg = DM
DM (
4-20
I0
,
M0
I1
,
M1
I2
,
M2
I3
,
M3
I0
,
M0
I1
,
M1
I2
,
M2
I3
,
M3
I4
,
M4
I5
,
M5
I6
,
M6
I7
,
M7
)
=
dreg
);
;
<data>
ADSP-218x DSP Instruction Set Reference
Instruction Set
Table 4-6. Move Instructions (Cont’d)
I4
,
M4
I5
,
M5
I6
,
M6
I7
,
M7
DM (<address>) = reg ;
reg = <data> ;
(
dreg = PM
PM (
I4
’
M4
I5
’
M5
I6
’
M6
I7
’
M7
I4
’
M4
I5
’
M5
I6
’
M6
I7
’
M7
)
=
);
dreg;
Table 4-7 shows how registers are grouped. These registers are read and
written via their register names.
ADSP-218x DSP Instruction Set Reference
4-21
Program Flow Control
Table 4-7. Processor Registers: reg and dreg
reg (registers)
dreg (Data Registers)
SB
PX
I0 – 17, M0 – M7, L0 – L7
AX0, AX1, AY0, AY1, AR
CNTR
MX0, MX1, MY0, MY1, MR0,
MR1, MR2
ASTAT, MSTAT, SSTAT
SI, SE, SR0, SR1
IMASK, ICNTL, IFC
TX0, TX1, RX0, RX1
Program Flow Control
Program flow control on the ADSP-218x processors is simple but powerful. Here is an example of one instruction:
IF EQ JUMP my_label;
JUMP,
of course, is a familiar construct from many other languages.
is any identifier you wish to use as a label for the destination
jumped to. Instead of the label, an index register in DAG2 may be explicitly used. The default scope for any label is the source code module in
which it is declared. The assembler directive .ENTRY makes a label visible as
an entry point for routines outside the module. Conversely, the .EXTERNAL
directive makes it possible to use a label declared in another module.
My_label
If the counter condition (DO UNTIL CE, IF NOT CE) is to be used, an assignment to CNTR must be executed to initialize the counter value. JUMP and
CALL permit the additional conditionals FLAG_IN and NOT FLAG_IN to be
used for branching on the state of the FI pin, but only with direct addressing, not with DAG2 as the address source.
4-22
ADSP-218x DSP Instruction Set Reference
Instruction Set
and RTI provide for conditional return from CALL or interrupt vectors
respectively.
RTS
The IDLE instruction provides a way to wait for interrupts. IDLE causes the
processor to wait in a low-power state until an interrupt occurs. When an
interrupt is serviced, control returns to the instruction following the IDLE
statement. IDLE uses less power than loops created with NOPs.
Table 4-8 gives a summary of all program flow control instructions. The
condition codes are described in Table 4-9.
Table 4-8. Program Flow Control Instructions
[IF cond]
JUMP
(I4)
;
(I5)
(I6)
(I7)
<address>
IF
FLAG_IN
JUMP
<address>;
NOT FLAG_IN
[IF cond]
CALL
(I4)
;
(I5)
(I6)
(I7)
<address>
IF
FLAG_IN
CALL
<address>;
NOT FLAG_IN
[IF cond]
RTS;
ADSP-218x DSP Instruction Set Reference
4-23
Program Flow Control
Table 4-8. Program Flow Control Instructions (Cont’d)
[IF cond]
RTI;
DO <address> [UNTIL termination];
IDLE [(n)];
Table 4-9. IF Status Condition Codes
Syntax
Status Condition
True If:
EQ
Equal Zero
AZ = 1
NE
Not Equal Zero
AZ = 0
LT
Less Than Zero
AN .XOR. AV = 1
GE
Greater Than or Equal Zero
AN .XOR. AV = 0
LE
Less Than or Equal Zero
(AN .XOR. AV) .OR. AZ = 1
GT
Greater Than Zero
(AN .XOR. AV) .OR. AZ = 0
AC
ALU Carry
AC = 1
NOT AC
Not ALU Carry
AC = 0
AV
ALU Overflow
AV = 1
NOT AV
Not ALU Overflow
AV = 0
MV
MAC Overflow
MV = 1
NOT MV
Not MAC Overflow
MV = 0
NEG X
Input Sign Negative
AS = 1
POS
X Input Sign Positive
AS = 0
NOT CE
Not Counter Expired
FLAG_IN1
FI pin
Last sample of FI pin = 1
NOT FLAG_IN1
Not FI pin
Last sample of FI pin = 0
1
4-24
Only available on JUMP and CALL instructions
ADSP-218x DSP Instruction Set Reference
Instruction Set
Miscellaneous Instructions
There are several miscellaneous instructions. NOP is a no operation instruction. The PUSH/POP instructions allow you to explicitly control the status,
counter, PC and loop stacks; interrupt servicing automatically pushes and
pops these stacks.
The Mode Control instruction enables and disables processor modes of
operation: bit-reversal on DAG1, latching ALU overflow, saturating the
ALU result register, choosing the primary or secondary register set, GO
mode for continued operation during bus grant, multiplier shift mode for
fractional or integer arithmetic, and timer enabling.
A single ENA or DIS can be followed by any number of mode identifiers,
separated by commas; ENA and DIS can also be repeated. All seven modes
can be enabled, disabled, or changed in a single instruction.
The MODIFY instruction modifies the address pointer in the I register
selected with the value in the selected M register, without performing any
actual memory access. As always, the I and M registers must be from the
same DAG; any of I0-I3 may be used only with one from M0-M3 and the
same for I4-I7 and M4-M7. If circular buffering is in use, modulus logic
applies. See the ADSP-218x DSP Hardware Reference Manual, Chapter 4,
“Data Address Generators” for more information.
The FO (Flag Out), FL0, FL1, and FL2 pins can each be set, cleared, or toggled. This instruction provides a control structure for multiprocessor
communication.
ADSP-218x DSP Instruction Set Reference
4-25
Miscellaneous Instructions
Table 4-10. Miscellaneous Instructions
NOP;
[
PUSH
STS] [, POP CNTR]
[, POP PC]
[,POP LOOP];
POP
ENA
BIT_REV
DIS
AV_LATCH
[,]
;
AR_SAT
SEC_REG
G_MODE
M_MODE
TIMER
MODIFY
(
[IF cond]
I0
,
M0
I1
,
M1
I2
,
M2
I3
,
M3
I4
,
M4
I5
,
M5
I6
,
M6
I7
,
M7
);
SET
FLAG_OUT
RESET
FL0
TOGGLE
FL1
FL2
ENA
INTS;
DIS
4-26
ADSP-218x DSP Instruction Set Reference
[,];
Instruction Set
Extra Cycle Conditions
All instructions execute in a single cycle except under certain conditions,
as explained below.
Multiple Off-Chip Memory Accesses
The data and address buses of the ADSP-218x processors are multiplexed
off-chip. Because of this occurrence, the processors can perform only one
off-chip access per instruction in a single cycle. If two off-chip accesses are
required such as the instruction fetch and one data fetch, or data fetches
from both program and data memory, then one overhead cycle occurs. In
this case the program memory access occurs first, followed by the data
memory access. If three off-chip accesses are required—the instruction
fetch as well as data fetches from both program and data memory—then
two overhead cycles occur.
A multifunction instruction requires three items to be fetched from memory: the instruction itself and two data words. No extra cycle is needed to
execute the instruction as long as only one of the fetches is from external
memory. This excludes external wait states or bus request holdoffs. Two
fetches must be from on-chip memory, either PM or DM.
Wait States
All family processors allow the programming of wait states for external
memory chips. Up to 15 extra wait state cycles for the ADSP-2185M,
ADSP-2186M, ADSP-2188M, ADSP-2189M, ADSP-2188N,
ADSP-2185N, ADSP-2186N, ADSP-2187N and ADSP-2189N DSPs
and up to seven extra wait state cycles for all other ADSP-218x models
may be added to the processor’s access time for external memory. Extra
cycles inserted due to wait states are in addition to any cycles caused by
multiple off-chip accesses. Wait state programming is described in the
ADSP-218x DSP Hardware Reference, Chapter 8, “Memory Interface”.
ADSP-218x DSP Instruction Set Reference
4-27
Instruction Set Syntax
Wait states and multiple off-chip memory accesses are the two cases when
an extra cycle is generated during instruction execution. The following
case, SPORT autobuffering and DMA, causes the insertion of extra cycles
between instructions.
SPORT Autobuffering and DMA
If serial port autobuffering or DMA is being used to transfer data words to
or from internal memory, then one memory access is “stolen” for each
transfer. The stolen memory access occurs only between complete instructions. If extra cycles are required to execute any instruction (for one of the
two reasons above), the processor waits until it is completed before “stealing” the access cycle.
Instruction Set Syntax
The following sections describe instruction set syntax and other notation
conventions used in the reference page of each instruction.
Punctuation and Multifunction Instructions
All instructions terminate with a semicolon. A comma separates the
clauses of a multifunction instruction but does not terminate it. For example, the statements below in Example A comprise one multifunction
instruction (which can execute in a single cycle). Example B shows two
separate instructions, requiring two instruction cycles.
Example A: One multifunction instruction
/* a comma is used in multifunction instructions */
AX0 = DM(I0, M0), or AX0 = DM(I0, M0),AY0 = PM(I4, M4);
AY0 = PM(I4, M4);
4-28
ADSP-218x DSP Instruction Set Reference
Instruction Set
Example B: Two separate instructions
/* a semicolon terminates an instruction */
AX0 = DM(I0, M0);
AY0 = PM(I4, M4);
Syntax Notation Example
Here is an example of one instruction, the ALU Add/Add with Carry
instruction:
[ IF cond ]
AR
AF
=
xop
+
yop
;
C
yop + C
The permissible conds, xops, and yops are given in a list. The conditional IF
clause is enclosed in square brackets, indicating that it is optional.
The destination register for the add operation must be either AR or AF.
These are listed within parallel bars, indicating that one of the two must
be chosen.
Similarly, the yop term may consist of a Y operand, the carry bit, or the
sum of both. One of these three terms must be used.
ADSP-218x DSP Instruction Set Reference
4-29
Instruction Set Syntax
Status Register Notation
The following notation is used in the discussion of the effect each instruction has on the processors’ status registers:
Table 4-11. Status Register Notation
Notation
Meaning
*
An asterisk indicates a bit in the status word that is changed by the execution
of the instruction.
–
A dash indicates that a bit is not affected by the instruction.
0 or 1
Indicates that a bit is unconditionally cleared or set.
For example, the status word ASTAT is shown below:
ASTAT:
7
6
5
4
3
2
1
0
SS
MV
AQ
AS
AC
AV
AN
AZ
–
*
–
–
–
0
–
–
Here the MV bit is updated and the AV bit is cleared.
4-30
ADSP-218x DSP Instruction Set Reference
Instruction Set
ALU Instructions
ALU instructions are:
• “Add/Add With Carry” on page 4-32
• “Subtract X-Y/Subtract X-Y With Borrow” on page 4-35
• “Subtract Y-X/Subtract Y-X With Borrow” on page 4-39
• “Bitwise Logic: AND, OR, XOR” on page 4-42
• “Bit Manipulation: TSTBIT, SETBIT, CLRBIT, TGLBIT” on
page 4-45
• “Clear: PASS” on page 4-48
• “Syntax” on page 4-32
• “NOT” on page 4-54
• “Absolute Value: ABS” on page 4-56
• “Increment” on page 4-58
• “Decrement” on page 4-60
• “Divide Primitives: DIVS and DIVQ” on page 4-62
• “Generate ALU Status Only: NONE” on page 4-70
ADSP-218x DSP Instruction Set Reference
4-31
ALU Instructions
Add/Add With Carry
Syntax
[ IF cond ]
AR
=
xop
+
AF
yop
+
+
;
C
yop + C
+ [constant]
+ [constant] + C
Permissible xops
AX0
MR2
AX1
MR1
AR
MR0
SR1
SR0
Permissible yops
AY0
AY1
AF
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Permissible constants
1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384,
32767, -2, -3, -5, -9, -17, -33, -65, -129, -257, -513, -1025, -2049, -4097,
-8193, -16385, -32768
Example
/* Conditional ADD with carry */
IF EQ AR = AX0 + AY0 + C;
/* Unconditional ADD */
AR = AR + 512;
/* ADD a negative constant */
AR = AX0 - 129;
/* AR = AX0 + (- 129) */
/* 32 Bit Addition: AX1:AX0 = AX1:AX0 + AY1:AY0 */
DIS AR_SAT;
/* If not already disabled */
AR = AX0 + AY0;
4-32
/* Add low words */
AR = AX1 + AY1 + C, AX0 = AR;
/* Add high words + carry
AX1 = AR;
/* Copy result if required */
ADSP-218x DSP Instruction Set Reference
*/
Instruction Set
Description
Test the optional condition and, if true, perform the specified addition. If
false then perform a no-operation. Omitting the condition performs the
addition unconditionally. The addition operation adds the first source
operand to the second source operand along with the ALU carry bit, AC, (if
designated by the +C notation), using binary addition. The result is stored
in the destination register. The operands are contained in the data registers or constant specified in the instruction.
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
AZ
Set if the result equals zero. Cleared otherwise.
Set if the result is negative. Cleared otherwise.
Set if an arithmetic overflow occurs. Cleared otherwise.
Set if a carry is generated. Cleared otherwise.
AN
AV
AC
6
MV
–
5
AQ
–
4
AS
*
3
AC
*
2
AV
*
1
AN
*
0
AZ
*
Instruction Format
Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
AMF
0
1
0
0
Z
AMF
Yop
Xop
8
7
6
5
4
3
0
0
0
0
COND
2
1
0
specifies the ALU or MAC operation, in this case:
AMF = 10010 for + yop + C
AMF = 10011 for xop + yop
Note that xop
Z:
+ C
is a special case of xop
Destination register
Yop:
+ yop + C
with
yop=0.
Y operand
ADSP-218x DSP Instruction Set Reference
4-33
ALU Instructions
Xop:
X operand
COND:
Condition
(xop + constant) Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
YY
8
Xop
7
6
CC
5
BO
4
3
2
1
COND
specifies the ALU or MAC operation, in this case:
AMF
AMF = 10010 for xop + constant + C
AMF = 10011 for xop + constant
Z:
Destination register
COND:
Xop:
X operand
BO, CC,
and YY specify the constant.
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• BO, CC, and YY “ALU/MAC Constant Codes” on page A-22
• “AMF Function Codes” on page A-9
• “ALU/MAC Result Register Codes” on page A-22
• “Y Operand Codes” on page A-21
4-34
ADSP-218x DSP Instruction Set Reference
0
Instruction Set
Subtract X-Y/Subtract X-Y With Borrow
Syntax
[ IF cond ]
AR
=
xop
–
AF
–
;
yop
yop +
C–1
+ C–1
– [constant]
– [constant] + C–1
Permissible xops
AX0
MR2
AX1
MR1
AR
MR0
SR1
SR0
Permissible yops
AY0
AY1
AF
Permissible status conditions
EQ
LE
AC
NE
NEG
NOT AC
MV
GT
POS
NOT MV
GE
AV
LT
NOT AV NOT CE
Permissible constants
0, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384,
32767, -2, -3, -5, -9, -17, -33, -65, -129, -257, -513, -1025, -2049, -4097,
-8193, -16385, -32768
Example
/* Conditional subtraction */
IF GE AR = AX0 - AY0;
/* Subtraction of the negative value -17 */
AR = AX0 + 17;
/* AR = AX0 -(-17) */
/* 32 Bit Subtraction: AX1:AX0 = AX1:AX0 - AY1:AY0 */
DIS AR_SAT;
/* If not already disabled */
AR = AX0 - AY0;
/* Subtract low words */
AR = AX1 - AY1 + C -1, AX0 = AR;
/* Sub high words - borrow */
AX1 = AR;
/* Copy result if required */
/* Negate MR Register MR = -MR */
DIS AR_SAT;
/* If not already disabled */
ADSP-218x DSP Instruction Set Reference
4-35
ALU Instructions
AR = -MR0;/* Negate low word */
AR = -MR1 + C -1, MR0 = AR;
/* Negate middle word - borrow */
AR = -MR2 + C -1, MR1 = AR;
/* Negate high word minus borrow */
MR2 = AR;
Description
Test the optional condition and, if true, then perform the specified subtraction. If the condition is not true then perform a no-operation.
Omitting the condition performs the subtraction unconditionally. The
subtraction operation subtracts the second source operand from the first
source operand, and optionally adds the ALU Carry bit (AC) minus 1
(0x0001), and stores the result in the destination register. The (C–1) quantity effectively implements a borrow capability for multiprecision
subtractions. The operands are contained in the data registers or constant
specified in the instruction.
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
AZ
Set if the result equals zero. Cleared otherwise.
Set if the result is negative. Cleared otherwise.
Set if an arithmetic overflow occurs. Cleared otherwise.
Set if a carry is generated. Cleared otherwise.
AN
AV
AC
6
MV
–
5
AQ
–
4
AS
*
3
AC
*
2
AV
*
1
AN
*
0
AZ
*
Instruction Format
Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
4-36
0
1
0
0
Z
AMF
Yop
8
Xop
ADSP-218x DSP Instruction Set Reference
7
6
5
4
3
0
0
0
0
COND
2
1
0
Instruction Set
specifies the ALU or MAC operation, in this case:
AMF
AMF = 10110 for xop – yop + C – 1 operation
AMF = 10111 for xop – yop operation
Note that xop
+ C – 1
is a special case of xop
– yop + C – 1
Z:
Destination register
Yop:
Y operand
Xop:
X operand
COND:
Condition
with yop=0.
(xop + constant) Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
YY
8
Xop
7
6
CC
5
BO
4
3
2
1
0
COND
specifies the ALU or MAC operation, in this case:
AMF
AMF = 10010 for xop – constant + C–1
AMF = 10011 for xop – constant
Z:
Destination register
Xop:
X operand
BO, CC,
COND:
Condition
and YY specify the constant.
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• BO, CC, and YY “ALU/MAC Constant Codes” on page A-22
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
ADSP-218x DSP Instruction Set Reference
4-37
ALU Instructions
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
4-38
ADSP-218x DSP Instruction Set Reference
Instruction Set
Subtract Y-X/Subtract Y-X With Borrow
Syntax
[ IF cond ]
AR
=
yop –
AF
xop
xop +
;
C – 1
- xop + C–1
– xop + constant
– xop + constant + C–1
Permissible xops
AX0
MR2
AX1
MR1
AR
MR0
SR1
SR0
Permissible yops
AY0
AY1
AF
Permissible status conditions
EQ
LE
AC
NE
NEG
NOT AC
MV
GT
POS
NOT MV
GE
AV
LT
NOT AV NOT CE
Permissible constants
0, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32767,
-2, -3, -5, -9, -17, -33, -65, -129, -257, -513, -1025, -2049, -4097, -8193,
-16385, -32768
Example
IF GT AR = AY0 – AX0 + C + 1;
Description
Test the optional condition and, if true, then perform the specified subtraction. If the condition is not true then perform a no-operation.
Omitting the condition performs the subtraction unconditionally. The
subtraction operation subtracts the second source operand from the first
source operand, and optionally adds the ALU Carry bit (AC) minus 1
(0x0001), and stores the result in the destination register. The (C–1) quantity effectively implements a borrow capability for multiprecision
subtractions. The operands are contained in the data registers or constant
specified in the instruction.
Status Generated
ADSP-218x DSP Instruction Set Reference
4-39
ALU Instructions
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
AZ
Set if the result equals zero. Cleared otherwise.
Set if the result is negative. Cleared otherwise.
Set if an arithmetic overflow occurs. Cleared otherwise.
Set if a carry is generated. Cleared otherwise.
AN
AV
AC
6
MV
–
5
AQ
–
4
AS
-
3
AC
*
2
AV
*
1
AN
*
0
AZ
*
Instruction Format
Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
Yop
8
Xop
7
6
5
4
3
2
0
0
0
0
COND
1
0
specifies the ALU or MAC operation, in this case:
AMF
AMF = 11010 for yop – xop + C – 1
AMF = 11001 for yop – xop
Note that –xop
Z:
+ C – 1
is a special case of yop
Destination register
X operand
Xop:
Yop:
COND:
– xop + C – 1
with yop=0.
Y operand
Condition
(-xop + constant) Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
AMF
0
1
0
0
Z
AMF
YY
8
Xop
6
specifies the ALU or MAC operation, in this case:
AMF = 11010 for constant – xop + C–1
AMF = 11001 for constant – xop
4-40
7
CC
ADSP-218x DSP Instruction Set Reference
5
BO
4
3
2
COND
1
0
Instruction Set
Z:
Destination register
COND:
Xop:
X operand
BO, CC,
and YY specify the constant.
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• BO, CC, and YY “ALU/MAC Constant Codes” on page A-22
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
ADSP-218x DSP Instruction Set Reference
4-41
ALU Instructions
Bitwise Logic: AND, OR, XOR
Syntax
[ IF cond ]
AR
=
xop
AF
AND
yop
OR
constant
;
XOR
Permissible xops
AX0
MR2
AX1
MR1
AR
MR0
SR1
SR0
Permissible yops
AY0
AY1
AF
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Permissible constants
0, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32767,
-2, -3, -5, -9, -17, -33, -65, -129, -257, -513, -1025, -2049, -4097, -8193,
-16385, -32768
Example
AR = AX0
XOR
AY0;
IF FLAG_IN AR = MR0 AND 8192;
Description
Test the optional condition and if true, then perform the specified bitwise
logical operation (logical AND, inclusive OR, or exclusive OR). If the condition is not true then perform a no-operation. Omitting the condition
performs the logical operation unconditionally. The operands are contained in the data registers or constant specified in the instruction.
Status Generated
4-42
ADSP-218x DSP Instruction Set Reference
Instruction Set
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
AZ
Set if the result equals zero. Cleared otherwise.
Set if the result is negative. Cleared otherwise.
Always cleared.
Always cleared.
AN
AV
AC
6
MV
–
5
AQ
–
4
AS
-
3
AC
0
2
AV
0
1
AN
*
0
AZ
*
Instruction Format
Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
Yop
8
Xop
7
6
5
4
3
2
1
0
0
0
0
COND
0
specifies the ALU or MAC operation, in this case:
AMF
AMF
= 11100 for AND operation
AMF
= 11101 for OR operation
AMF
= 11110 for XOR operation
Z:
Destination register
Yop:
Y operand
Xop:
X operand
COND:
Condition
(xop AND/OR/XOR constant) Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
AMF
0
1
0
0
Z
AMF
YY
Xop
8
7
6
CC
5
BO
4
3
2
1
0
COND
specifies the ALU or MAC operation, in this case:
AMF
= 11100 for AND operation
ADSP-218x DSP Instruction Set Reference
4-43
ALU Instructions
AMF
= 11101 for OR operation
AMF
= 11110 for XOR operation
Z:
Destination register
COND:
Xop:
X operand
BO, CC,
and YY specify the constant.
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• BO, CC, and YY “ALU/MAC Constant Codes” on page A-22
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
4-44
ADSP-218x DSP Instruction Set Reference
Instruction Set
Bit Manipulation: TSTBIT, SETBIT, CLRBIT, TGLBIT
Syntax
[ IF cond ]
AR
=
TSTBIT n OF xop
AF
;
SETBIT n OF xop
CLRBIT n OF xop
TGLBIT n OF xop
Permissible xops
AX0
MR2
AX1
MR1
AR
MR0
SR1
SR0
Permissible conds
LE
EQ
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Permissible n values (0=LSB)
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
Example
AF = TSTBIT 5 OF AR;
AR = TGLBIT 13 OF AX0;
/* The instruction displays in the debugger as AR = AX0 XOR
8192; which is the equivalent of the instruction AR = TGLBIT13
OF AX0. */
Description
Test the optional condition and if true, then perform the specified bit
operation. If the condition is not true then perform a no-operation. Omitting the condition performs the operation unconditionally. These
operations cannot be used in multifunction instructions.
These operations are defined as follows:
•
TSTBIT
is an AND operation with a 1 in the selected bit
•
SETBIT
is an OR operation with a 1 in the selected bit
ADSP-218x DSP Instruction Set Reference
4-45
ALU Instructions
•
CLRBIT
is an AND operation with a 0 in the selected bit
•
TGLBIT
is an XOR operation with a 1 in the selected bit
The ASTAT status bits are affected by these instructions. The following
instructions could be used, for example, to test a bit and branch
accordingly:
AF=TSTBIT 5 OF AR;
IF NE JUMP set;
/*Jump to set if bit 5 of AR is set*/
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
AZ
Set if the result equals zero. Cleared otherwise.
Set if the result is negative. Cleared otherwise.
Always cleared.
Always cleared.
AN
AV
AC
6
MV
–
5
AQ
–
4
AS
-
3
AC
0
2
AV
0
1
AN
*
0
AZ
*
Instruction Format
(xop AND/OR/XOR constant) Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
AMF
4-46
0
1
0
0
Z
AMF
YY
8
Xop
7
6
CC
specifies the ALU or MAC operation, in this case:
AMF
= 11100 for AND operation
AMF
= 11101 for OR operation
AMF
= 11110 for XOR operation
ADSP-218x DSP Instruction Set Reference
5
BO
4
3
2
COND
1
0
Instruction Set
Z:
Destination register
COND:
Xop:
X operand
BO, CC,
and YY specify the constant.
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• BO, CC, and YY “ALU/MAC Constant Codes” on page A-22
• “ALU/MAC Result Register Codes” on page A-22
• “X Operand Codes” on page A-21
ADSP-218x DSP Instruction Set Reference
4-47
ALU Instructions
Clear: PASS
Syntax
[ IF cond ]
AR
=
PASS
AF
xop
;
yop
constant
Permissible xops
AX0
MR2
AX1
MR1
AR
MR0
SR1
SR0
Permissible yops
AY0
AY1
AF
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Permissible constants
0, 1, 2, 3, 4, 5, 7, 8, 9, 15, 16, 17, 31, 32, 33, 63, 64, 65, 127, 128, 129, 255, 256, 257,
511, 512, 513, 1023, 1024, 1025, 2047, 2048, 2049, 4095, 4096, 4097, 8191, 8192, 8193,
16383, 16384, 16385, 32766, 32767
-1, -2, -3, -4, -5, -6, -8, -9, -10, -16, -17, -18, -32, -33, -34, -64, -65, -66, -128, -129, -130,
-256, -257, -258, -512, -513, -514, -1024, -1025, -1026, -2048, -2049, -2050, -4096,
-4097, -4098, -8192, -8193, -8194, -16384, -16385, -16386, -32767, -32768
Example
/* Conditional pass*/
IF GE AR = PASS AY0;
/* Unconditional pass*/
AR = PASS 0;
AR = PASS 8191;
/* Single-cycle register swap */
AR = PASS AX0, AX0 = AR;
/* Clip AX0 by AY0 */
/* AR = SIGN(AX0) * MIN(AX0,AY0);*/
DIS AR_SAT;
4-48
/* Disable
ADSP-218x DSP Instruction Set Reference
*/
Instruction Set
AF = AY0 - AX0, AR = AX0;
/* Check if X > Y
IF GT AR = PASS AY0;
*/
/* If yes saturate X By Y */
IF LT AF = AX0 + AY0;
/* Y - (-X) = X + Y */
IF LT AR = -AY0;
/* If X < -Y saturate X By - Y */
Description
Test the optional condition and if true, pass the source operand unmodified through the ALU block and store in the destination register. If the
condition is not true perform a no-operation. Omitting the condition performs the PASS unconditionally. The source operand is contained in the
data register or constant specified in the instruction.
is one method of clearing AR. The PASS 0 instruction can also be
combined with memory reads and writes in a multifunction instruction to
clear AR.
PASS 0
The PASS instruction performs the transfer to the AR or AF register and
affects the ASTAT status flags (for xop, yop, -1, 0, 1 only). This instruction
is different from a register move operation which does not affect any status
flags. The PASS constant operation (using any constant other than –1, 0, or
1) causes the ASTAT status flags to be undefined.
The PASS constant operation (using any constant other than –1, 0, or 1)
may not be used in multifunction instructions.
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
AZ
Set if the result equals zero. Cleared otherwise.
Set if the result is negative. Cleared otherwise.
Always cleared.
Always cleared.
AN
AV
AC
6
MV
–
5
AQ
–
4
AS
–
3
AC
0
2
AV
0
1
AN
*
ADSP-218x DSP Instruction Set Reference
0
AZ
*
4-49
ALU Instructions
Instruction Format
Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
Yop
8
Xop
7
6
5
4
3
2
0
0
0
0
COND
1
0
1
0
specifies the ALU or MAC operation, in this case:
AMF
AMF
= 10000 for PASS
yop
AMF
= 10011 for PASS
xop
AMF
= 10001 for
AMF
= 11000 for PASS
PASS 1
–1
Note the following:
PASS xop
PASS 1
is a special case of xop
is a special case of xop
PASS yop – 1
+ yop
+ 1,
with yop
with yop
is a special case of yop
- 1,
= 0
= 0
with yop
Z:
Destination register
Yop:
Y operand
Xop:
X operand
COND:
Condition
= 0
Conditional ALU/MAC operation, Instruction Type 9:
(PASS constant; constant ≠ 0,1, –1)
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
4-50
0
1
0
0
Z
AMF
YY
Xop
8
7
CC
ADSP-218x DSP Instruction Set Reference
6
5
BO
4
3
2
COND
Instruction Set
specifies the ALU or MAC operation, in this case:
AMF
AMF
= 10000 for PASS
yop
AMF
= 10001 for PASS
yop + 1
AMF
= 11000 for PASS yop
– 1
Z:
Destination register
COND:
Xop:
X operand
BO, CC,
and YY specify the constant.
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• BO, CC, and YY “ALU/MAC Constant Codes” on page A-22
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
ADSP-218x DSP Instruction Set Reference
4-51
ALU Instructions
Negate
Syntax
[ IF cond ]
AR
= –
AF
Permissible xops
AX0 MR2
AX1 MR1
AR
MR0
SR1
SR0
xop
;
yop
Permissible yops
AY0
AY1
AF
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
IF LT AR = – AY0;
Description
Test the optional condition and if true, then NEGATE the source operand
and store in the destination location. If the condition is not true then perform a no-operation. Omitting the condition performs the NEGATE
operation unconditionally. The source operand is contained in the data
register specified in the instruction.
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
AZ
Set if the result equals zero. Cleared otherwise.
Set if the result is negative. Cleared otherwise.
Set if operand = 0x8000. Cleared otherwise.
Set if operand equals zero. Cleared otherwise.
AN
AV
AC
4-52
6
MV
–
5
AQ
–
4
AS
–
3
AC
*
ADSP-218x DSP Instruction Set Reference
2
AV
*
1
AN
*
0
AZ
*
Instruction Set
Instruction Format
Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
Yop
8
Xop
7
6
5
4
3
2
0
0
0
0
COND
1
0
specifies the ALU or MAC operation, in this case:
AMF
AMF
= 10101 for
AMF
= 11001 for –
Note that –
xop
operation
– yop
xop
operation
is a special case of yop
– xop,
with yop specified to be 0.
Z:
Destination register
Yop:
Y operand
Xop:
X operand
COND:
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
ADSP-218x DSP Instruction Set Reference
4-53
ALU Instructions
NOT
Syntax
[ IF cond ]
AR
= NOT
AF
Permissible xops
AX0
MR2
AX1
MR1
AR
MR0
SR1
SR0
xop
;
yop
Permissible yops
AY0
AY1
AF
0
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
IF NE AF = NOT AX0;
Description
Test the optional condition and if true, then perform the logical complement (ones complement) of the source operand and store in the
destination location. If the condition is not true then perform a no-operation. Omitting the condition performs the complement operation
unconditionally. The source operand is contained in the data register
specified in the instruction.
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
AZ
Set if the result equals zero. Cleared otherwise.
Set if the result is negative. Cleared otherwise.
Always cleared.
Always cleared.
AN
AV
AC
4-54
6
MV
–
5
AQ
–
4
AS
–
3
AC
0
ADSP-218x DSP Instruction Set Reference
2
AV
0
1
AN
*
0
AZ
*
Instruction Set
Instruction Format
Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
Yop
8
Xop
7
6
5
4
3
2
0
0
0
0
COND
1
0
specifies the ALU or MAC operation, in this case:
AMF
AMF
= 10100 for NOT
yop
operation
AMF
= 11011 for NOT
xop
operation
Z:
Destination register
Yop:
Y operand
Xop:
X operand
COND:
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
ADSP-218x DSP Instruction Set Reference
4-55
ALU Instructions
Absolute Value: ABS
Syntax
[ IF cond ]
AR
= ABS xop ;
AF
Permissible xops
AX0
MR2
AX1
MR1
AR
MR0
SR1
SR0
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
/* Conditional instruction */
IF NEG AF = ABS AX0;
/* Clip AX0 by AY0 */
/* AR = sign(AX0) * min(AX0,AY0); */
ENA AR_SAT;
/* Enable
*/
AR = ABS AX0;
/* Modify AS flag
*/
AF = AY0 - AR;
/* Check if ABS(X) > Y
*/
IF LT AR = PASS AY0;
/* If yes saturate X by Y */
IF NEG AR = -AR;
/* If X < 0
*/
Description
Test the optional condition and, if true, then take the absolute value of
the source operand and store in the destination location. If the condition
is not true then perform a no-operation. Omitting the condition performs
the absolute value operation unconditionally. The source operand is contained in the data register specified in the instruction.
Status Generated
4-56
ADSP-218x DSP Instruction Set Reference
Instruction Set
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
AZ
Set if the result equals zero. Cleared otherwise.
Set if xop is 0x8000. Cleared otherwise.
Set if xop is 0x8000. Cleared otherwise.
Always cleared.
Set if the source operand is negative. Cleared otherwise.
AN
AV
AC
AS
6
MV
–
5
AQ
–
4
AS
*
3
AC
0
2
AV
*
1
AN
*
0
AZ
*
Instruction Format
Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
0
0
8
Xop
7
6
5
4
3
2
0
0
0
0
COND
1
0
specifies the ALU or MAC operation. In this case:
AMF
AMF
= 11111 for ABS
xop
Z:
Destination register
Xop:
X operand
operation
COND:
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
ADSP-218x DSP Instruction Set Reference
4-57
ALU Instructions
Increment
Syntax
[ IF cond ]
AR
= yop + 1 ;
AF
Permissible yops
AY0
AX0
AY1
AX1
AF
MR0
AR
MR1
SR0
MR2
SR1
Permissible conds
EQ
LE
NE
NEG
POS
GT
AV
GE
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
IF GT AF = AF + 1;
Description
Test the optional condition and if true, then increment the source operand by 0x0001 and store in the destination location. If the condition is not
true then perform a no-operation. Omitting the condition performs the
increment operation unconditionally. The source operand is contained in
the data register specified in the instruction.
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
AZ
Set if the result equals zero. Cleared otherwise.
Set if the result is negative. Cleared otherwise.
Set if an overflow is generated. Cleared otherwise.
Set if a carry is generated. Cleared otherwise.
AN
AV
AC
4-58
6
MV
–
5
AQ
–
4
AS
–
3
AC
*
ADSP-218x DSP Instruction Set Reference
2
AV
*
1
AN
*
0
AZ
*
Instruction Set
Instruction Format
Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
Yop
8
Xop
7
6
5
4
3
2
0
0
0
0
COND
1
0
specifies the ALU or MAC operation, in this case:
AMF
AMF
= 10001 for yop
+ 1
operation
Note that the xop field is ignored for the increment operation.
Z:
Destination register
Yop:
Y operand
Xop:
X operand
COND:
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
ADSP-218x DSP Instruction Set Reference
4-59
ALU Instructions
Decrement
Syntax
[ IF cond ]
AR
= yop – 1 ;
AF
Permissible yops
AY0
AX0
AY1
AX1
AF
MR0
AR
MR1
SR0
MR2
SR1
Permissible conds
EQ
LE
NE
NEG
POS
GT
AV
GE
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
IF EQ AR = AY1 – 1;
Description
Test the optional condition and if true, then decrement the source operand by 0x0001 and store in the destination location. If the condition is not
true then perform a no-operation. Omitting the condition performs the
decrement operation unconditionally. The source operand is contained in
the data register specified in the instruction.
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
AZ
Set if the result equals zero. Cleared otherwise.
Set if the result is negative. Cleared otherwise.
Set if an overflow is generated. Cleared otherwise.
Set if a carry is generated. Cleared otherwise.
AN
AV
AC
4-60
6
MV
–
5
AQ
–
4
AS
–
3
AC
*
ADSP-218x DSP Instruction Set Reference
2
AV
*
1
AN
*
0
AZ
*
Instruction Set
Instruction Format
Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
Yop
8
Xop
7
6
5
4
3
2
0
0
0
0
COND
1
0
specifies the ALU or MAC operation, in this case:
AMF
AMF = 11000 for yop – 1 operation
Note that the xop field is ignored for the decrement operation.
Z:
Destination register
Yop:
Y operand
Xop:
X operand
COND:
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
ADSP-218x DSP Instruction Set Reference
4-61
ALU Instructions
Divide Primitives: DIVS and DIVQ
Syntax
DIVS
yop, xop
;
DIVQ
xop
;
Permissible xops
AX0
MR2
AX1
MR1
AR
MR0
SR1
SR0
Permissible yops
AY1
AF
Description
These instructions implement yop÷xop. There are two divide primitives,
DIVS and DIVQ. A single precision divide, with a 32-bit numerator and a
16-bit denominator, yielding a 16-bit quotient, executes in 16 cycles.
Higher precision divides are also possible.
The division can be either signed or unsigned, but both the numerator
and denominator must be the same; both signed or unsigned. The programmer sets up the divide by sorting the upper half of the numerator in
any permissible yop (AY1 or AF), the lower half of the numerator in AY0,
and the denominator in any permissible xop. The divide operation is then
executed with the divide primitives, DIVS and DIVQ. Repeated execution of
DIVQ implements a non-restoring conditional add-subtract division algorithm. At the conclusion of the divide operation, the quotient is in AY0.
To implement a signed divide, first execute the DIVS instruction once,
which computes the sign of the quotient. Then execute the DIVQ instruction for as many times as there are bits remaining in the quotient (for
example, for a signed, single-precision divide, execute DIVS once and DIVQ
15 times).
4-62
ADSP-218x DSP Instruction Set Reference
Instruction Set
To implement an unsigned divide, first place the upper half of the numerator in AF, then set the AQ bit to zero by manually clearing it in the
Arithmetic Status Register, ASTAT. This indicates that the sign of the quotient is positive. Then execute the DIVQ instruction for as many times as
there are bits in the quotient (for example, for an unsigned single-precision divide, execute DIVQ 16 times).
The quotient bit generated on each execution of DIVS and DIVQ is the AQ
bit which is written to the ASTAT register at the end of each cycle. The final
remainder produced by this algorithm (and left over in the AF register) is
not valid and must be corrected if it is needed.
For more information, refer to “Division Theory” on page 4-64, “Division
Exceptions” on page 4-67, and “Division Applications” on page 4-68.
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
6
MV
–
5
AQ
*
4
AS
–
3
AC
–
2
AV
–
1
AN
–
0
AZ
–
AQ
Loaded with the bit value equal to the AQ bit computed on each cycle from execution of
the DIVS or DIVQ instruction.
Instruction Format
DIVQ, Instruction Type 23:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
0
1
1
1
0
0
0
1
0
8
Xop
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
DIVQ, Instruction Type 24:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
0
1
1
0
0
0
0
Yop
Xop
8
ADSP-218x DSP Instruction Set Reference
4-63
ALU Instructions
Xop:
X operand
Yop:
Y operand
Division Theory
The ADSP-218x processors’ instruction set contains two instructions for
implementing a non-restoring divide algorithm. These instructions take as
their operands twos-complement or unsigned numbers, and in sixteen
cycles produce a truncated quotient of sixteen bits. For most numbers and
applications, these primitives produce the correct results. However, there
are certain situations where results produced are off by one LSB. This section documents these situations, and presents alternatives for producing
the correct results.
Computing a 16-bit fixed-point quotient from two numbers is accomplished by 16 executions of the DIVQ instruction for unsigned numbers.
Signed division uses the DIVS instruction first, followed by fifteen DIVQs.
Regardless of which division you perform, both input operands must be of
the same type (signed or unsigned) and produce a result of the same type.
These two instructions are used to implement a conditional add/subtract,
non-restoring division algorithm. As its name implies, the algorithm functions by adding or subtracting the divisor to/from the dividend. The
decision as to which operation is performed is based on the previously
generated quotient bit. Each add/subtract operation produces a new partial remainder, which is used in the next step.
The phrase non-restoring refers to the fact that the final remainder is not
correct. With a restoring algorithm, it is possible, at any step, to take the
partial quotient, multiply it by the divisor, and add the partial remainder
to recreate the dividend. With this non-restoring algorithm, it is necessary
to add two times the divisor to the partial remainder if the previously
determined quotient bit is zero. It is easier to compute the remainder
using the multiplier than in the ALU.
4-64
ADSP-218x DSP Instruction Set Reference
Instruction Set
Signed Division
Signed division is accomplished by first storing the 16-bit divisor in an
Xop register (AX0, AX1, AR, MR2, MR1, MR0, SR1, or SR0). The 32-bit dividend
must be stored in two separate 16-bit registers. The lower 16-bits must be
stored in AY0, while the upper 16-bits can be in either AY1 or AF.
The DIVS primitive is executed once, with the proper operands (for example, DIVS AY1, AX0) to compute the sign of the quotient. The sign bit of the
quotient is determined by XORing (exclusive-or) the sign bits of each operand. The entire 32-bit dividend is shifted left one bit. The lower fifteen
bits of the dividend with the recently determined sign bit appended are
stored in AY0, while the lower fifteen bits of the upper word, with the
MSB of the lower word appended is stored in AF.
To complete the division, 15 DIVQ instructions are executed. Operation of
the DIVQ primitive is described below.
Unsigned Division
Computing an unsigned division is done like signed division, except the
first instruction is not a DIVS, but another DIVQ. The upper word of the
dividend must be stored in AF, and the AQ bit of the ASTAT register must be
set to zero before the divide begins.
The DIVQ instruction uses the AQ bit of the ASTAT register to determine if
the dividend should be added to, or subtracted from the partial remainder
stored in AF and AY0. If AQ is zero, a subtract occurs. A new value for AQ is
determined by XORing the MSB of the divisor with the MSB of the dividend. The 32-bit dividend is shifted left one bit, and the inverted value of
AQ is moved into the LSB.
Output Formats
As in multiplication, the format of a division result is based on the format
of the input operands. The division logic has been designed to work most
efficiently with fully fractional numbers, those most commonly used in
ADSP-218x DSP Instruction Set Reference
4-65
ALU Instructions
fixed-point DSP applications. A signed, fully fractional number uses one
bit before the binary point as the sign, with fifteen (or thirty-one in double precision) bits to the right, for magnitude.
If the dividend is in M.N format (M bits before the binary point, N bits
after), and the divisor is O.P format, the quotient’s format is
(M-O+1).(N-P-1). As you can see, dividing a 1.31 number by a 1.15
number produces a quotient whose format is (1-1+1).(31-15-1) or 1.15.
dividing two numbers, you must ensure that the format of
L Before
the quotient is valid. For example, if you attempted to divide a
32.0 number by a 1.15 number the result would attempt to be in
(32-1+1).(0-15-1) or 32.-16 format. This cannot be represented in
a 16-bit register!
In addition to proper output format, you must ensure that a divide overflow does not occur. Even if a division of two numbers produces a legal
output format, it is possible that the number overflows, and is unable to
fit within the constraints of the output. For example, if you wished to
divide a 16.16 number by a 1.15 number, the output format would be
(16-1+1).(16-15-1) or 16.0 which is legal. Now assume you happened to
have 16384 (0x4000) as the dividend and .25 (0x2000) as the divisor, the
quotient would be 65536, which does not fit in 16.0 format. This operation would overflow, producing an erroneous result.
Input operands can be checked before division to ensure that an overflow
does not result. If the magnitude of the upper 16 bits of the dividend is
larger than the magnitude of the divisor, an overflow results.
Integer Division
One special case of division that deserves special mention is integer division. There may be some cases where you wish to divide two integers, and
produce an integer result. It can be seen that an integer-integer division
produces an invalid output format of (32-16+1).(0-0-1), or 17.-1.
4-66
ADSP-218x DSP Instruction Set Reference
Instruction Set
To generate an integer quotient, you must shift the dividend to the left
one bit, placing it in 31.1 format. The output format for this division is
(31-16+1).(1-0-1), or 16.0. You must ensure that no significant bits are
lost during the left shift, or an invalid result is generated.
Division Exceptions
Although the divide primitives for the ADSP-218x processors work correctly in most instances, there are two cases where an invalid or inaccurate
result can be generated. The first case involves signed division by a negative number. If you attempt to use a negative number as the divisor, the
quotient generated may be one LSB less than the correct result. The other
case concerns unsigned division by a divisor greater than 0x7FFF. If the
divisor in an unsigned division exceeds 0x7FFF, an invalid quotient is
generated.
Negative Divisor Error
The quotient produced by a divide with a negative divisor is generally one
LSB less than the correct result. The divide algorithm implemented on the
ADSP-218x processors does not correctly compensate for the twos-complement format of a negative number, causing this inaccuracy.
There is one case where this discrepancy does not occur. If the result of
the division operation should equal 0x8000, then it is correctly represented, and not be one LSB off.
There are several ways to correct for this error. Before changing any code,
however, you should determine if a one-LSB error in your quotient is a
significant problem. In some cases, the LSB is small enough to be insignificant. If you find it necessary to have exact results, two solutions are
possible.
One is to avoid division by negative numbers. If your divisor is negative,
take its absolute value and invert the sign of the quotient after division.
This produces the correct result.
ADSP-218x DSP Instruction Set Reference
4-67
ALU Instructions
Another technique would be to check the result by multiplying the quotient by the divisor. Compare this value with the dividend, and if they are
off by more than the value of the divisor, increase the quotient by one.
Unsigned Division Error
Unsigned divisions can produce erroneous results if the divisor is greater
than 0x7FFF. You should not attempt to divide two unsigned numbers if
the divisor has a one in the MSB. If it is necessary to perform a such a
division, both operands should be shifted right one bit. This maintains the
correct orientation of operands.
Shifting both operands may result in a one LSB error in the quotient. This
can be solved by multiplying the quotient by the original (not shifted)
divisor. Subtract this value from the original dividend to calculate the
error. If the error is greater than the divisor, add one to the quotient, if it
is negative, subtract one from the quotient.
Division Applications
Each of the problems mentioned in “Division Exceptions” on page 4-67
can be compensated for in software. Listing 4-1 shows the program section divides. This code can be used to divide two signed or unsigned
numbers to produce the correct quotient, or an error condition.
that the
instruction must be placed 15 (or 16) times
L Note
15 (or 16) times
explicitly. A hardware loop that executes
DIVQ
DIVQ
does not work correctly.
Listing 4-1. Division Routine Using DIVS and DIVQ
/*signed division algorithm with fix for negative division error
inputs:
4-68
ay1
- 16 MSB of numerator
ay0
- 16 LSB of numerator
ar
- denominator
ADSP-218x DSP Instruction Set Reference
Instruction Set
outputs:
ar
- corrected quotient
intermediate (scratch) registers:
mr0, af
*/
signed_div:
mr0 = ar, ar = abs ar;
/*
save copy of denominator, make it positive
*/
divs ay1, ar; divq ar;
divq ar;
divq ar;
divq ar;
divq ar;
divq ar;
divq ar;
divq ar;
divq ar;
divq ar;
divq ar;
divq ar;
divq ar;
divq ar;
divq ar;
ar = ay0, af = pass mr0;
/* place output in ar, get sign of denominator */
if LT ar = - ay0;
/* if neg, place inverted output in ar
*/
rts;
See Also
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
ADSP-218x DSP Instruction Set Reference
4-69
ALU Instructions
Generate ALU Status Only: NONE
Syntax
NONE = <ALU>;
/* Cannot be coupled with a data move instruction */
<ALU> may be any unconditional ALU operation except DIVS or DIVQ.
Example
NONE = AX0 – AY0;
NONE = PASS SR0;
Description
Perform the designated ALU operation, generate the ASTAT status flags,
then discard the result value. This instruction allows the testing of register
values without disturbing the contents of the AR or AF registers.
that the following ALU operations of the ADSP-218x procesL Note
sors are exceptions:
(xop + constant)
SUBTRACT X-Y (xop + constant)
SUBTRACT Y-X (-xop + constant)
AND/OR/XOR (xop • constant)
PASS (constant ≠ 0,1, –1)
ADD
TSTBIT,SETBIT,CLRBIT,TGLBIT
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
AZ
Set if the result equals zero. Cleared otherwise.
4-70
6
MV
–
5
AQ
–
4
AS
–
3
AC
*
ADSP-218x DSP Instruction Set Reference
2
AV
*
1
AN
*
0
AZ
*
Instruction Set
Set if the result is negative. Cleared otherwise.
Set if an arithmetic overflow occurs. Cleared otherwise.
Set if carry is generated. Cleared otherwise.
AN
AV
AC
Instruction Format
Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
1
0
AMF*
Yop
Xop
8
7
6
5
4
3
2
1
0
1
0
1
0
1
0
1
0
* ALU codes only.
specifies the ALU or MAC operation (only ALU operations allowed).
AMF
Xop:
X operand
Yop:
Y operand
See Also
• “AMF Function Codes” on page A-9
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
ADSP-218x DSP Instruction Set Reference
4-71
MAC Instructions
MAC Instructions
MAC instructions are:
• “Multiply” on page 4-73
• “Multiply With Cumulative Add” on page 4-77
• “Multiply With Cumulative Subtract” on page 4-81
• “Squaring” on page 4-85
• “MAC Clear” on page 4-88
• “MAC Transfer MR” on page 4-90
• “Conditional MR Saturation” on page 4-92
4-72
ADSP-218x DSP Instruction Set Reference
Instruction Set
Multiply
Syntax
[ IF cond ]
MR
= xop *
MF
yop
(SS)
xop
(SU)
;
(US)
(UU)
(RND)
Permissible xops
MX0
AR
MX1
SR1
MR2
SR0
MR1
MR0
Permissible yops
MY0
MY1
MF
0
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
/* Conditional multiply xop * yop */
IF EQ MR = MX0 * MF (UU);
/* Unconditional multiply xop * yop */
MF = SR0 * SRO (SS);
/* 32-bit multiply: MR2:MR1:MR0:SR1:SR0 = MX1:MX0 * MY1:MY0 */
DIS M_MODE;
/* Use fractional mode */
MR = MX0 * MY0 (UU);
/* Multiply low words
*/
AR = PASS MR0, MR0 = MR1;
/* Right shift by 16
*/
MR1 = MR2;
MR = MR + MX1 * MY0 (SU), SR0 = AR; /* Multiply middle words */
MR = MR + MX0 * MY1 (US);
AR = PASS MR0, MR0 = MR1;
/* Right shift by 16 */
MR1 = MR2;
MR = MR + MX1 * MY1 (SS), SR1 = AR;
/* Multiply high word */
Description
ADSP-218x DSP Instruction Set Reference
4-73
MAC Instructions
Test the optional condition and, if true, then multiply the two source
operands and store in the destination location. If the condition is not true
perform a no-operation. Omitting the condition performs the multiplication unconditionally. The operands are contained in the data registers
specified in the instruction. When MF is the destination operand, only bits
31-16 of the product are stored in MF.
The data format selection field following the two operands specifies
whether each respective operand is in Signed (S) or Unsigned (U) format.
The xop is specified first and yop is second. If the xop * xop operation is
used, the data format selection field must be (UU), (SS), or (RND) only.
There is no default; one of the data formats must be specified.
If RND (Round) is specified, the MAC multiplies the two source operands,
rounds the result to the most significant 24 bits (or rounds bits 31-16 to
16 bits if there is no overflow from the multiply), and stores the result in
the destination register. The two multiplication operands xop and yop (or
xop and xop) are considered to be in twos complement format. Rounding
can be either biased or unbiased. For a discussion of biased vs. unbiased
rounding, see the section “Rounding Mode” in the ADSP-218x DSP Hardware Reference Manual, Chapter 2, “Computational Units.”
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
6
MV
*
5
AQ
–
4
AS
–
3
AC
–
MV
Set on MAC overflow (if any of the upper 9 bits of MR are not all one or zero). Cleared
otherwise.
Instruction Format
4-74
ADSP-218x DSP Instruction Set Reference
2
AV
–
1
AN
–
0
AZ
–
Instruction Set
(xop * yop) Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
Yop
8
Xop
7
6
5
4
3
2
0
0
0
0
COND
1
0
specifies the ALU or MAC operation, in this case:
AMF
AMF
FUNCTION
Data Format
X-Operand
Y-Operand
00100
xop * xop
(SS)
Signed
Signed
00101
xop * yop
(SU)
Signed
Unsigned
00110
xop * yop
(US)
Unsigned
Signed
00111
xop * yop
(UU)
Unsigned
Unsigned
00001
xop * yop
(RND)
Signed
Signed
Z:
Destination register
Yop:
Y operand
Xop:
X operand
COND:
Condition
(xop * xop) Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
AMF
0
1
0
0
Z
AMF
0
0
Xop
8
7
6
5
4
3
0
0
0
1
COND
1
0
specifies the ALU or MAC operation, in this case:
AMF
FUNCTION
Data Format
X-Operand
00100
xop * xop
(SS)
Signed
00111
xop * xop
(UU)
Unsigned
00001
xop * xop
(RND)
Signed
Z:
2
Destination register
COND:
Condition
ADSP-218x DSP Instruction Set Reference
4-75
MAC Instructions
Xop:
X operand register
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
4-76
ADSP-218x DSP Instruction Set Reference
Instruction Set
Multiply With Cumulative Add
Syntax
[ IF cond ]
MR
= MR + xop *
MF
yop
(SS)
xop
(SU)
;
(US)
(UU)
(RND)
Permissible xops
MX0
AR
MX1
SR1
MR2
SR0
MR1
MR0
Permissible yops
MY0
MY1
MF
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Examples
/* Conditional multiply with cumulative add, xop * yop
*/
IF GE MR = MR + MX0 * MY1 (SS);
/* Unconditional multiply with cumulative add, xop * yop */
MF = SR0 * SRO (SS);
/* 40-bit accumulation of 16-bit integer values */
ENA M_MODE;
/* Use integer mode */
MR = 0, MX0 = DM(I0,M0);
/* Load first X
*/
MY0 = 1
CNTR = N-1;
DO ADDLOOP UNTIL CE;
ADDLOOP: MR = MR + MX0 * MY0 (SS), MX0 = DM(I0,M0);
MR = MR + MX0 * MY0 (SS);
Description
ADSP-218x DSP Instruction Set Reference
4-77
MAC Instructions
Test the optional condition and, if true, then multiply the two source
operands, add the product to the present contents of the MR register, and
store the result in the destination location. If the condition is not true
then perform a no-operation. Omitting the condition performs the multiply/accumulate unconditionally. The operands are contained in the data
registers specified in the instruction. When MF is the destination operand,
only bits 31-16 of the 40-bit result are stored in MF.
The ADSP-218x processors support the xop * xop squaring operation.
Both xops must be in the same register. This option allows single-cycle X2
and ∑X2 instructions.
The data format selection field to the right of the two operands specifies
whether each respective operand is in signed (S) or unsigned (U) format.
The xop is specified first and yop is second. If the xop * xop operation is
used, the data format selection field must be (UU), (SS), or (RND) only.
There is no default; one of the data formats must be specified.
If RND (Round) is specified, the MAC multiplies the two source operands,
adds the product to the current contents of the MR register, rounds the
result to the most significant 24 bits (or rounds bits 31-16 to the nearest
16 bits if there is no overflow from the multiply/accumulate), and stores
the result in the destination register. The two multiplication operands xop
and yop (or xop and xop) are considered to be in twos complement format.
All rounding is unbiased, except on the ADSP-217x, ADSP-218x, and
ADSP-21msp58/59 processors, which offer a biased rounding mode. For a
discussion of biased vs. unbiased rounding, see the section “Rounding
Mode” in the ADSP-218x DSP Hardware Reference Manual, Chapter 2,
“Computational Units.”
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
4-78
7
SS
–
6
MV
*
5
AQ
–
4
AS
–
3
AC
–
ADSP-218x DSP Instruction Set Reference
2
AV
–
1
AN
–
0
AZ
–
Instruction Set
Set on MAC overflow (if any of the upper 9 bits of MR are not all one or zero). Cleared
otherwise.
MV
Instruction Format
(xop * yop) Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
Yop
8
Xop
7
6
5
4
3
2
0
0
0
0
COND
1
0
specifies the ALU or MAC operation, in this case:
AMF
AMF
FUNCTION
Data Format
X-Operand
Y-Operand
01000
MR + xop * xop
(SS)
Signed
Signed
01001
MR + xop * yop
(SU)
Signed
Unsigned
01010
MR + xop * yop
(US)
Unsigned
Signed
01011
MR + xop * yop
(UU)
Unsigned
Unsigned
00010
MR + xop * yop
(RND)
Signed
Signed
Z:
Destination register
Yop:
Xop:
X operand register
COND:
Y operand register
Condition
(xop * xop) Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
AMF
0
1
0
0
Z
AMF
0
0
Xop
8
7
6
5
4
3
2
0
0
0
1
COND
1
0
specifies the ALU or MAC operation, in this case:
AMF
FUNCTION
Data Format
X-Operand
01000
MR + xop * xop
(SS)
Signed
ADSP-218x DSP Instruction Set Reference
4-79
MAC Instructions
AMF
FUNCTION
Data Format
X-Operand
01011
MR + xop * xop
(UU)
Unsigned
00010
MR + xop * xop
(RND)
Signed
Z:
Xop:
Destination register
X operand register
COND:
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
4-80
ADSP-218x DSP Instruction Set Reference
Instruction Set
Multiply With Cumulative Subtract
Syntax
[ IF cond ]
MR
= MR – xop *
MF
yop
(SS)
xop
(SU)
;
(US)
(UU)
(RND)
Permissible xops
MX0
AR
MX1
SR1
MR2
SR0
MR1
MR0
Permissible yops
MY0
MY1
MF
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
IF LT MR = MR – MX1 * MY0 (SU);
/* xop * yop */
MR = MR – MX0 * MX0 (SS);
/* xop * yop */
Description
Test the optional condition and, if true, then multiply the two source
operands, subtract the product from the present contents of the MR register, and store the result in the destination location. If the condition is not
true perform a no-operation. Omitting the condition performs the multiply/subtract unconditionally. The operands are contained in the data
registers specified in the instruction. When MF is the destination operand,
only bits 16-31 of the 40-bit result are stored in MF.
The ADSP-218x DSPs support the xop * xop squaring operation. Both
xops must be in the same register. This option allows single-cycle X2 and
∑X2 instructions.
ADSP-218x DSP Instruction Set Reference
4-81
MAC Instructions
The data format selection field to the right of the two operands specifies
whether each respective operand is in signed (S) or unsigned (U) format.
The xop is specified first and yop is second. If the xop * xop operation is
used, the data format selection field must be (UU), (SS), or (RND) only.
There is no default; one of the data formats must be specified.
If RND (Round) is specified, the MAC multiplies the two source operands,
subtracts the product from the current contents of the MR register,
rounds the result to the most significant 24 bits (or rounds bits 31-16 to
16 bits if there is no overflow from the multiply/accumulate), and stores
the result in the destination register. The two multiplication operands xop
and yop (or xop and xop) are considered to be in twos complement format.
The ADSP-218x processors support biased rounding mode, as well as,
unbiased rounding. For a discussion of biased versus unbiased rounding,
see the section “Rounding Mode” in the ADSP-218x DSP Hardware Reference Manual, Chapter 2, “Computational Units.”
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
6
MV
*
5
AQ
–
4
AS
–
3
AC
–
2
AV
–
1
AN
–
0
AZ
–
MV
Set on MAC overflow (if any of the upper 9 bits of MR are not all one or zero). Cleared
otherwise.
Instruction Format
(xop * yop) Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
4-82
0
1
0
0
Z
AMF
Yop
Xop
8
7
6
5
4
3
0
0
0
0
COND
ADSP-218x DSP Instruction Set Reference
2
1
0
Instruction Set
specifies the ALU or MAC operation, in this case:
AMF
AMF
FUNCTION
Data Format
X-Operand
Y-Operand
01100
MR – xop * xop
(SS)
Signed
Signed
01101
MR – xop * yop
(SU)
Signed
Unsigned
01110
MR – xop * yop
(US)
Unsigned
Signed
01111
MR – xop * yop
(UU)
Unsigned
Unsigned
00011
MR – xop * yop
(RND)
Signed
Signed
Z:
Destination register
Xop: X operand register
Yop:
Y operand register
COND: Condition
(xop * xop) Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
0
0
8
Xop
7
6
5
4
3
2
0
0
0
1
COND
1
0
specifies the ALU or MAC operation, in this case:
AMF
AMF
FUNCTION
Data Format
X-Operand
01100
MR – xop * xop
(SS)
Signed
01111
MR – xop * xop
(UU)
Unsigned
00011
MR – xop * xop
(RND)
Signed
Z:
Destination register
Xop:
X operand register
COND:
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
ADSP-218x DSP Instruction Set Reference
4-83
MAC Instructions
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
4-84
ADSP-218x DSP Instruction Set Reference
Instruction Set
Squaring
Syntax
[IF cond]
MR
=
MR + xop * xop
MF
(SS)
;
(UU)
(RND)
[IF cond]
MR
=
MR - xop * xop
MF
(SS)
;
(UU)
(RND)
[IF cond]
MR
MF
=
xop * xop
(SS)
;
(UU)
(RND)
Permissible xops
MX0
AR
MX1
SR1
MR2
SR0
MR1
MR0
ADSP-218x DSP Instruction Set Reference
4-85
MAC Instructions
Examples
ΣX2Instruction
ΣX2 instruction
IF NOT MV MR = MR + MX0 * MX0 (SS);
/*
IF NOT MV MR = MR - MX0 * MX0 (SS);
/*
MR = AR * AR (UU);
/* X instruction
2
*/
*/
*/
Description
Test the optional condition and, if true, then square the xop, add the
present contents of the MR register (or subtract the squared result from the
MR register), and store the result in the destination location. If the condition is not true, then perform a no-operation. Omitting the condition
performs the multiply/accumulate unconditionally. The xop is contained
in the data register specified in the instruction. When MF is the destination
operand, only bits 31-16 of the 40-bit result are stored in MF.
Restrictions
The ADSP-218x DSPs support the xop * xop squaring operation. However, both xops must be in the same register. This option allows
single-cycle X2 and ΣX2 instructions. The data format selection field must
be (UU), (SS), or (RND) only. There is no default for the data format selection field; one of the data formats must be specified. The squaring
instruction cannot be used in a multifunction instruction.
Status Generated
ASTAT:
MV
4-86
7
6
5
4
3
2
1
0
SS
MV
AQ
AS
AC
AV
AN
AZ
-
*
-
-
-
-
-
-
Set on MAC overflow (if any of upper 9 bits of MR are not all one or zero).
Cleared otherwise.
ADSP-218x DSP Instruction Set Reference
Instruction Set
Instruction Format
(xop * xop) Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
0
0
8
Xop
7
6
5
4
3
2
0
0
0
1
COND
1
0
AMF specifies the ALU or MAC operation. In this case:
AMF
Function
Data Format
X-Operand
01000
MR + xop * xop
(SS)
Signed
01011
MR + xop * xop
(UU)
Unsigned
00010
MR + xop * xop
(RND)
Signed
Z:
Destination register
Xop:
X operand
COND:
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
• “X Operand Codes” on page A-21
ADSP-218x DSP Instruction Set Reference
4-87
MAC Instructions
MAC Clear
Syntax
[ IF cond ]
MR
= 0;
MF
Permissible conds
EQ
NE
LE
NEG
AC
NOT AC
GT
POS
MV
GE
AV
NOT MV
LT
NOT AV
NOT CE
Example
IF GT MR = 0;
Description
Test the optional condition and, if true, then set the specified register to
zero. If the condition is not true perform a no-operation. Omitting the
condition performs the clear unconditionally. The entire 40-bit MR or
16-bit MF register is cleared to zero.
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
6
MV
0
MV
Always cleared.
5
AQ
–
4
AS
–
3
AC
–
2
AV
–
1
AN
–
0
AZ
–
Instruction Format
Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
0
0
0
0
0
0
COND
4-88
0
1
0
0
Z
AMF
1
1
0
0
ADSP-218x DSP Instruction Set Reference
2
1
0
Instruction Set
AMF
specifies the ALU or MAC operation, in this case,
AMF = 00100
for Clear operation.
Note that this instruction is a special case of xop
zero.
Z:
Destination register
COND:
* yop,
with yop set to
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
ADSP-218x DSP Instruction Set Reference
4-89
MAC Instructions
MAC Transfer MR
Syntax
[ IF cond ]
MR
= MR
[(RND)]
;
MF
Permissible conds
EQ
NE
LE
NEG
AC
NOT AC
GT
POS
MV
GE
AV
NOT MV
LT
NOT AV
NOT CE
Example
IF EQ MF = MR (RND);
MR0 = DM(MR0_VAL);
/* Conditional transfer MR */
/* Load MR register */
MR1 = DM(MR1_VAL);
MR2 = DM(MR2_VAL);
MR = MR;
/* Update the MV flag */
IF MV SAT MR;
Description
Test the optional condition and, if true, then perform the MR transfer
according to the description below. If the condition is not true then perform a no-operation. Omitting the condition performs the transfer
unconditionally. Since RND is optional, the MR = MR instruction can be used
to update the MV flag when the MR register is loaded by register moves.
This instruction actually performs a multiply/accumulate, specifying yop
= 0 as a multiplicand and adding the zero product to the contents of MR.
The MR register may be optionally rounded at the boundary between bits
15 and 16 of the result by specifying the RND option. If MF is specified as
the destination, bits 31-16 of the result are stored in MF. If MR is the destination, the entire 40-bit result is stored in MR.
Status Generated
4-90
ADSP-218x DSP Instruction Set Reference
Instruction Set
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
–
6
MV
*
5
AQ
–
4
AS
–
3
AC
–
2
AV
–
1
AN
–
0
AZ
–
MV
Set on MAC overflow if any of upper 9 bits of MR are not one or zero. Cleared otherwise.
Instruction Format
Conditional ALU/MAC operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
0
0
0
0
0
0
COND
AMF
0
1
0
0
Z
AMF
1
1
0
0
1
0
specifies the ALU or MAC operation, in this case,
AMF = 01000
for
Transfer MR
operation.
Note that this instruction is a special case of MR
to zero.
Z:
2
Destination register
COND:
+ xop * yop,
with yop set
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “ALU/MAC Result Register Codes” on page A-22
• “AMF Function Codes” on page A-9
ADSP-218x DSP Instruction Set Reference
4-91
MAC Instructions
Conditional MR Saturation
Syntax
IF MV SAT MR;
Description
Test the MV (MAC Overflow) bit in the Arithmetic Status Register
(ASTAT), and if set, then saturate the lower-order 32 bits of the 40-bit MR
register; if the MV is not set then perform a no-operation.
Saturation of MR is executed with this instruction for one cycle only; MAC
saturation is not a continuous mode that is enabled or disabled. The saturation instruction is intended to be used at the completion of a series of
multiply/accumulate operations so that temporary overflows do not cause
the accumulator to saturate.
The saturation result depends on the state of MV and on the sign of MR (the
MSB of MR2). The possible results after execution of the saturation instruction are shown in the table below.
MV
MSB
of MR2
MR Contents after Saturation
0
0
No change
0
1
No change
1
0
00000000 0111111111111111 1111111111111111
1
1
11111111 1000000000000000 0000000000000000
Status Generated
No status bits affected.
Instruction Format
4-92
ADSP-218x DSP Instruction Set Reference
Instruction Set
Saturate MR operation, Instruction Type 25:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
ADSP-218x DSP Instruction Set Reference
4-93
Shifter Instructions
Shifter Instructions
Shifter instructions are:
• “Arithmetic Shift” on page 4-95
• “Logical Shift” on page 4-98
• “Normalize” on page 4-101
• “Derive Exponent” on page 4-104
• “Block Exponent Adjust” on page 4-107
• “Arithmetic Shift Immediate” on page 4-109
• “Logical Shift Immediate” on page 4-111
4-94
ADSP-218x DSP Instruction Set Reference
Instruction Set
Arithmetic Shift
Syntax
[ IF cond ] SR = [SR OR] ASHIFT xop
(HI)
;
(LO)
Permissible xops
SI
AR
SR1
MR2
SR0
MR1
MR0
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
/ * Conditional arithmetic shift */
IF LT SR = SR OR ASHIFT SI (LO);
/* Shift the content of SR arithmetically right by SE */
SE = -2;
SR = ASHIFT SR1 (HI), SI = SR0;
SR = SR OR LSHIFT SI (LO);
Description
Test the optional condition and, if true, then perform the designated
arithmetic shift. If the condition is not true, then perform a no-operation.
Omitting the condition performs the shift unconditionally. The operation
arithmetically shifts the bits of the operand by the amount and direction
specified in the shift code from the SE register. Positive shift codes cause a
left shift (upshift) and negative codes cause a right shift (downshift).
The shift may be referenced to the upper half of the output field (HI
option) or to the lower half (LO option). The shift output may be logically
ORed with the present contents of the SR register by selecting the SR OR
option.
ADSP-218x DSP Instruction Set Reference
4-95
Shifter Instructions
For ASHIFT with a positive shift code (that is, a positive value in SE), the
operand is shifted left; with a negative shift code (for example, negative
value in SE), the operand is shifted right. The number of positions shifted
is the count in the shift code. The 32-bit output field is sign-extended to
the left (the MSB of the input is replicated to the left), and the output is
zero-filled from the right. Bits shifted out of the high order bit in the
32-bit destination field (SR31) are dropped. Bits shifted out of the low
order bit in the destination field (SR0) are dropped.
To shift a double-precision number, the same shift code is used for both
halves of the number. On the first cycle, the upper half of the number is
shifted using an ASHIFT with the HI option; on the following cycle, the
lower half of the number is shifted using an LSHIFT with the LO and OR
options. This prevents sign bit extension of the lower word’s MSB.
Status Generated
No status bits affected.
Instruction Format
Conditional Shift Operation, Instruction Type 16:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
1
1
1
0
0
SF
SF
Shifter Function
0100
ASHIFT (HI)
0101
ASHIFT (HI, OR)
0110
ASHIFT (LO)
0111
ASHIFT (LO, OR)
Xop:
4-96
Shifter operand
COND:
8
Xop
Condition
ADSP-218x DSP Instruction Set Reference
7
6
5
4
3
2
0
0
0
0
COND
1
0
Instruction Set
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “Shifter Function Codes” on page A-18
• “X Operand Codes” on page A-21
ADSP-218x DSP Instruction Set Reference
4-97
Shifter Instructions
Logical Shift
Syntax
[ IF cond ] SR = [SR OR] LSHIFT xop
(HI)
;
(LO)
Permissible xops
SI
AR
SR1
MR2
SR0
MR1
MR0
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
IF GE SR = SR LSHIFT SI (HI);
Description
Test the optional condition and, if true, then perform the designated logical shift. If the condition is not true, then perform a no-operation.
Omitting the condition performs the shift unconditionally. The operation
logically shifts the bits of the operand by the amount and direction specified in the shift code from the SE register. Positive shift codes cause a left
shift (upshift) and negative codes cause a right shift (downshift).
The shift may be referenced to the upper half of the output field (HI
option) or to the lower half (LO option). The shift output may be logically
ORed with the present contents of the SR register by selecting the SR OR
option.
For LSHIFT with a positive shift code, the operand is shifted left; the numbers of positions shifted is the count in the shift code. The 32-bit output
field is zero-filled from the right. Bits shifted out of the high order bit in
the 32-bit destination field (SR31) are dropped.
4-98
ADSP-218x DSP Instruction Set Reference
Instruction Set
For LSHIFT with a negative shift code, the operand is shifted right; the
number of positions shifted is the count in the shift code. The 32-bit output field is zero-filled from the left. Bits shifted out of the low order bit in
the destination field (SR0) are dropped.
To shift a double-precision number, the same shift code is used for both
halves of the number. On the first cycle, the upper half of the number is
shifted using the HI option; on the following cycle, the lower half of the
number is shifted using the LO and OR options.
Status Generated
No status bits affected.
Instruction Format
Conditional Shift operation, Instruction Type 16:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
1
1
1
0
0
SF
SF
Shifter Function
0000
LSHIFT (HI)
0001
LSHIFT (HI, OR)
0010
LSHIFT (LO)
0011
LSHIFT (LO, OR)
Xop:
Shifter operand
COND:
8
Xop
7
6
5
4
3
2
0
0
0
0
COND
1
0
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
ADSP-218x DSP Instruction Set Reference
4-99
Shifter Instructions
• “Shifter Function Codes” on page A-18
• “X Operand Codes” on page A-21
4-100
ADSP-218x DSP Instruction Set Reference
Instruction Set
Normalize
Syntax
[ IF cond ] SR = [SR OR] NORM xop
(HI)
;
(LO)
Permissible xops
SI
AR
SR1
MR2
SR0
MR1
MR0
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Examples
/* Normalize instruction without condition */
SR = NORM SI (HI);
/* Clear the last bits of SR0 as specified by SE */
SE = DM(NUM_OF_BITS);
/* even 0 is allowed
*/
SR = NORM SR0 (LO);
/* shift to the right */
SR = LSHIFT SR0 (LO);
/* shift back to left */
Description
Test the optional condition and, if true, then perform the designated normalization. If the condition is not true, then perform a no-operation.
Omitting the condition performs the normalize unconditionally. The
operation arithmetically shifts the input operand to eliminate all but one
of the sign bits. NORM shifts the in the opposite direction of ASHIFT. The
amount of the shift comes from the SE register. The SE register may be
loaded with the proper shift code to eliminate the redundant sign bits by
using the Derive Exponent instruction; the shift code loaded is the negative of the quantity: (the number of sign bits minus one).
ADSP-218x DSP Instruction Set Reference
4-101
Shifter Instructions
The shift may be referenced to the upper half of the output field (HI
option) or to the lower half (LO option). The shift output may be logically
ORed with the present contents of the SR register by selecting the SR OR
option. When the LO reference is selected, the 32-bit output field is
zero-filled to the left. Bits shifted out of the high order bit in the 32-bit
destination field (SR31) are dropped.
The 32-bit output field is zero-filled from the right. If the exponent of an
overflowed ALU result was derived with the HIX modifier, the 32-bit output field is filled from left with the ALU Carry (AC) bit in the Arithmetic
Status Register (ASTAT) during a NORM (HI) operation. In this case (SE=1
from the exponent detection on the overflowed ALU value) a downshift
occurs.
To normalize a double-precision number, the same shift code is used for
both halves of the number. On the first cycle, the upper half of the number is shifted using the HI option; on the following cycle, the lower half of
the number is shifted using the LO and OR options.
Status Generated
No status bits affected.
Instruction Format
Conditional Shift operation, Instruction Type 16:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
1
1
1
0
0
SF
SF
Shifter Function
1000
NORM (HI)
1001
NORM (HI, OR)
1010
NORM (LO)
1011
NORM (LO, OR)
4-102
Xop
8
7
6
5
4
3
0
0
0
0
COND
ADSP-218x DSP Instruction Set Reference
2
1
0
Instruction Set
Xop:
Shifter operand
COND:
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “Shifter Function Codes” on page A-18
• “X Operand Codes” on page A-21
ADSP-218x DSP Instruction Set Reference
4-103
Shifter Instructions
Derive Exponent
Syntax
[ IF cond ] SE = EXP xop
(HI)
;
(LO)
(HIX)
Permissible xops
SI
AR
SR1
MR2
SR0
MR1
MR0
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Examples
/* Conditional derive exponent */
IF GT SE = EXP MR1 (HI);
/* Normalize 32-bit data to one sign bit to get the
best precision during arithmetic calculations */
/* First determine the exponent of the 32-bit register SR */
SE = EXP SR1 (HI);
SE = EXP SR0 (LO);
/* Second, normalize to one sign bit */
SR = NORM SR1 (HI), SI = SR0;
SR = SR OR NORM SI (LO);
/* Do your calculations */
/* Last, shift data back to original weight */
SR = ASHIFT SR1 (HI), SI = SR0;
SR = SR OR LSHIFT SI (LO);
Description
4-104
ADSP-218x DSP Instruction Set Reference
Instruction Set
Test the optional condition and, if true, perform the designated exponent
operation. If the condition is not true, then perform a no-operation.
Omitting the condition performs the exponent operation unconditionally.
The EXP operation derives the effective exponent of the input operand to
prepare for the normalization operation (NORM). The EXP operation supplies the source operand to the exponent detector, which generates a shift
code from the number of leading sign bits in the input operand. The shift
code, stored in SE at the completion of the EXP instruction, is the effective
exponent of the input value. The shift code depends on which exponent
detector mode is used (HI, HIX, LO).
In the HI mode, the input is interpreted as a single precision signed number, or as the upper half of a double-precision signed number. The
exponent detector counts the number of leading sign bits in the source
operand and stores the resulting shift code in SE. The shift code equals the
negative of the number of redundant sign bits in the input.
In the HIX mode, the input is interpreted as the result of an add or subtract
which may have overflowed. HIX is intended to handle shifting and normalization of results from ALU operations. The HIX mode examines the
ALU Overflow bit (AV) in the Arithmetic Status Register: if AV is set, then
the effective exponent of the input is +1 (indicating that an ALU overflow
occurred before the EXP operation), and +1 is stored in SE. If AV is not set,
then HIX performs exactly the same operations as the HI mode.
In the LO mode, the input is interpreted as the lower half of a double precision number. In performing the EXP operation on a double precision
number, the higher half of the number must first be processed with EXP in
the HI or HIX mode, and then the lower half can be processed with EXP in
the LO mode. If the upper half contained a non-sign bit, then the correct
shift code was generated in the HI or HIX operation and that is the code
that is stored in SE. If, however, the upper half was all sign bits, then EXP
in the LO mode totals the number of leading sign bits in the double precision word and stores the resulting shift code in SE.
ADSP-218x DSP Instruction Set Reference
4-105
Shifter Instructions
Status Generated
(See Table 4-11 on page 4-30 for register notation)
ASTAT:
7
SS
*
6
MV
–
5
AQ
–
4
AS
–
3
AC
–
2
AV
–
1
AN
–
0
AZ
–
SS
Set by the MSB of the input for an EXP operation in the HI or HIX mode with AV = 0.
Set by the MSB inverted in the HIX mode with AV = 1. Not affected by operations in
the LO mode.
Instruction Format
Conditional Shift operation, Instruction Type 16:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
1
1
1
0
0
SF
Shifter Function
1100
EXP (HI)
1101
EXP (HIX)
1110
EXP (LO)
Xop:
Shifter operand
SF
8
Xop
COND:
7
6
5
4
3
0
0
0
0
COND
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “Shifter Function Codes” on page A-18
• “X Operand Codes” on page A-21
4-106
ADSP-218x DSP Instruction Set Reference
2
1
0
Instruction Set
Block Exponent Adjust
Syntax
[ IF cond ] SB = EXPADJ xop;
Permissible xops
SI
AR
SR1
MR2
SR0
MR1
MR0
Permissible conds
EQ
LE
NE
NEG
GT
POS
GE
AV
LT
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
IF GT SB = EXPADJ SI ;
Description
Test the optional condition and, if true, perform the designated exponent
operation. If the condition is not true, then perform a no-operation.
Omitting the condition performs the exponent operation unconditionally.
The Block Exponent Adjust operation, when performed on a series of
numbers, derives the effective exponent of the number largest in magnitude. This exponent can then be associated with all of the numbers in a
block floating-point representation.
The Block Exponent Adjust circuitry applies the input operand to the
exponent detector to derive its effective exponent. The input must be a
signed twos complement number. The exponent detector operates in HI
mode (see the EXP instruction, above).
At the start of a block, the SB register should be initialized to –16 to set SB
to its minimum value. On each execution of the EXPADJ instruction, the
effective exponent of each operand is compared to the current contents of
the SB register. If the new exponent is greater than the current SB value, it
is written to the SB register, updating it. Therefore, at the end of the
ADSP-218x DSP Instruction Set Reference
4-107
Shifter Instructions
block, the SB register contains the largest exponent found. The EXPADJ
instruction is only an inspection operation; no actual shifting takes place
since the true exponent is not known until all the numbers in the block
have been checked. However, the numbers can be shifted at a later time
after the true exponent has been derived.
Extended (overflowed) numbers and the lower halves of double precision
numbers can not be processed with the Block Exponent Adjust
instruction.
Status Generated
No status bits affected.
Instruction Format
Conditional Shift operation, Instruction Type 16:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
SF
= 1111
Xop:
0
0
1
1
1
0
Shifter operand
0
SF
8
Xop
COND:
7
6
5
4
3
0
0
0
0
COND
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “Shifter Function Codes” on page A-18
• “X Operand Codes” on page A-21
4-108
ADSP-218x DSP Instruction Set Reference
2
1
0
Instruction Set
Arithmetic Shift Immediate
Syntax
SR = [SR OR] ASHIFT xop BY <exp>
(HI)
;
(LO)
Permissible xops
SI
MR0
SR1
MR1
SR0
MR2
AR
<exp>
Any constant between –128 and 127*
*See the ADSP-218x DSP Hardware Reference Manual, Chapter 2, “Computational Units.”
Example
SR = SR OR ASHIFT SR0 BY 3 (LO);
/* Do not use +3 */
Description
Arithmetically shift the bits of the operand by the amount and direction
specified by the constant in the exponent field. Positive constants cause a
left shift (upshift) and negative constants cause a right shift (downshift). A
positive constant must be entered without a + sign.
The shift may be referenced to the upper half of the output field (HI
option) or to the lower half (LO option). The shift output may be logically
ORed with the present contents of the SR register by selecting the SR OR
option.
For ASHIFT with a positive shift constant, the operand is shifted left; with a
negative shift constant the operand is shifted right. The 32-bit output
field is sign-extended to the left (the MSB of the input is replicated to the
left), and the output is zero-filled from the right. Bits shifted out of the
high order bit in the 32-bit destination field (SR31) are dropped. Bits
shifted out of the low order bit in the destination field (SR0) are dropped.
ADSP-218x DSP Instruction Set Reference
4-109
Shifter Instructions
To shift a double precision number, the same shift constant is used for
both halves of the number. On the first cycle, the upper half of the number is shifted using an ASHIFT with the HI option; on the following cycle,
the lower half is shifted using an LSHIFT with the LO and OR options. This
prevents sign bit extension of the lower word’s MSB.
Status Generated
No status bits affected.
Instruction Format
Shift Immediate operation, Instruction Type 15:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
1
1
1
1
0
SF
SF
Shifter Function
0100
ASHIFT (HI)
0101
ASHIFT (HI, OR)
1110
ASHIFT (LO)
0111
ASHIFT (LO, OR)
Xop:
Shifter operand
<exp>:
8
Xop
7
5
4
<exp>
8-bit signed shift value
See Also
• “Shifter Function Codes” on page A-18
• “X Operand Codes” on page A-21
4-110
6
ADSP-218x DSP Instruction Set Reference
3
2
1
0
Instruction Set
Logical Shift Immediate
Syntax
Permissible xops
SI
MR0
SR1
MR1
SR0
MR2
AR
<exp>
Any constant between –128 and 127*
* See the ADSP-218x DSP Hardware Reference Manual, Chapter 2, “Computational Units.”
Example
/* Shift the MR register into SR by -5 arithmetically */
SR = LSHIFT MR0 BY -5 (LO);
/* Shift right */
SR = SR OR LSHIFT MR1 BY -5 (HI);
/* Shift right */
SR = SR OR LSHIFT MR2 BY 16-5 (HI);
/* Shift left */
Description
Logically shifts the bits of the operand by the amount and direction specified by the constant in the exponent field. Positive constants cause a left
shift (upshift); negative constants cause a right shift (downshift). A positive constant must be entered without a + sign.
The shift may be referenced to the upper half of the output field (HI
option) or to the lower half (LO option). The shift output may be logically
ORed with the contents of the SR register by selecting the SR OR option.
For LSHIFT with a positive shift constant, the operand is shifted left. The
32-bit output field is zero-filled to the left and from the right. Bits shifted
out of the high order bit in the 32-bit destination field (SR31) are dropped.
For LSHIFT with a negative shift constant, the operand is shifted right. The
32-bit output field is zero-filled from the left and to the right. Bits shifted
out of the low order bit are dropped.
ADSP-218x DSP Instruction Set Reference
4-111
Shifter Instructions
To shift a double precision number, the same shift constant is used for
both parts of the number. On the first cycle, the upper half of the number
is shifted using the HI option; on the following cycle, the lower half is
shifted using the LO and OR options.
Status Generated
No status bits affected.
Instruction Format
Shift Immediate Operation, Instruction Type 15:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
1
1
1
1
0
SF
SF
Shifter Function
0000
LSHIFT (HI)
0001
LSHIFT (HI, OR)
0010
LSHIFT (LO)
0011
LSHIFT (LO, OR)
Xop:
Shifter operand
8
Xop
<exp>:
7
5
4
3
8-bit signed shift value
See Also
• “Shifter Function Codes” on page A-18
• “X Operand Codes” on page A-21
4-112
6
<exp>
ADSP-218x DSP Instruction Set Reference
2
1
0
Instruction Set
Move Instructions
The Move instructions are:
• “Register Move” on page 4-114
• “Load Register Immediate” on page 4-116
• “Data Memory Read (Direct Address)” on page 4-118
• “Data Memory Read (Indirect Address)” on page 4-120
• “Program Memory Read (Indirect Address)” on page 4-122
• “Data Memory Write (Direct Address)” on page 4-124
• “Data Memory Write (Indirect Address)” on page 4-126
• “Program Memory Write (Indirect Address)” on page 4-129
• “IO Space Read/Write” on page 4-131
ADSP-218x DSP Instruction Set Reference
4-113
Move Instructions
Register Move
Syntax
reg = reg;
Permissible registers
AX0
MX0
AX1
MX1
AY0
MY0
AY1
MY1
AR
MR2
MR1
MR0
SI
SE
SR1
SR0
I0-I7
M0-M7
L0-L7
SB
PX
ASTAT
MSTAT
SSTAT (read only)
IMASK
ICNTL
CNTR
OWRCNTR (write only)
RX0
RX1
TX0
TX1
IFC (write only)
Example
I7 = AR;
Description
Move the contents of the source to the destination location. The contents
of the source are always right-justified in the destination location after the
move.
When transferring a smaller register to a larger register (for example, an
8-bit register to a 16-bit register), the value stored in the destination is
either sign-extended to the left if the source is a signed value, or zero-filled
to the left if the source is an unsigned value. The unsigned registers which
(when used as the source) cause the value stored in the destination to be
zero-filled to the left are: I0 through I7, L0 through L7, CNTR, PX, ASTAT,
MSTAT, SSTAT, IMASK, and ICNTL. All other registers cause sign-extension to
the left.
When transferring a larger register to a smaller register (for example,, a
16-bit register to a 14-bit register), the value stored in the destination is
right-justified (bit 0 maps to bit 0) and the higher-order bits are dropped.
Note that whenever MR1 is loaded with data, it is sign-extended into MR2.
4-114
ADSP-218x DSP Instruction Set Reference
Instruction Set
Status Generated
No status bits affected.
Instruction Format
Internal Data Move, Instruction Type 17:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
1
1
0
1
0
0
0
0
DST
RGP
8
SRC
RGP
7
6
DEST
REG
5
4
3
2
1
0
SOURCE
REG
To choose the source register group (SRC RGP) and the source register
(SOURCE REG), refer to the table Table A-51 on page A-17.
To choose the destination register group (DST RGP) and the destination
register (DEST REG), refer to the table Table A-51 on page A-17.
ADSP-218x DSP Instruction Set Reference
4-115
Move Instructions
Load Register Immediate
Syntax
reg = <data>;
dreg = <data>;
data:
<constant>
Permissible registers
dregs (Instruction Type 6)
(16-bit load)
AX0
MX0
SI
AX1
MX1
SE
AY0
MY0
SR1
AY1
MY1
SR0
AR
MR2
MR1
MR0
dregs (Instruction Type 7)
(maximum 14-bit load)
SB
CNTR
PX
OWRCNTR (write only)
ASTAT
RX0
MSTAT
RX1
IMASK
TX0
ICNTL
TX1
I0-I7
IFC (write only)
M0-M7
L0-L7
Example
I0 = data_buffer;
L0 = length(data_buffer);
Description
Move the data value specified to the destination location. The data may be
a constant, or any symbol referenced by name or with the length operator.
The data value is contained in the instruction word, with 16 bits for data
register loads and up to 14 bits for other register loads. The value is always
right-justified in the destination location after the load (bit 0 maps to bit
0). When a value of length less than the length of the destination is
moved, it is sign-extended to the left to fill the destination width.
Note that whenever MR1 is loaded with data, it is sign-extended into MR2.
4-116
ADSP-218x DSP Instruction Set Reference
Instruction Set
For this instruction only, the RX and TX registers may be loaded with a
maximum of 14 bits of data (although the registers themselves are 16 bits
wide). To load these registers with 16-bit data, use the register-to-register
move instruction or the data memory-to-register move instruction with
direct addressing.
Status Generated
No status bits affected.
Instruction Format
Load Register Immediate, Instruction Type 6:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
1
0
0
8
7
6
5
4
DATA
3
2
1
0
DREG
contains the immediate value to be loaded into the Data Register
destination location. The data is right-justified in the field, so the value
loaded into an N-bit destination register is contained in the lower-order N
bits of the DATA field.
DATA
To choose the data register (DREG), refer to the table “DREG Selection
Codes” on page A-12.
Load Non-Data Register Immediate, Instruction Type 7:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
1
RGP
DATA
8
7
6
5
4
3
2
1
0
REG
contains the immediate value to be loaded into the Non-Data Register destination location. The data is right-justified in the field, so the value
loaded into an N-bit destination register is contained in the lower-order N
bits of the DATA field.
DATA
To choose the source register group (SRC RGP) and the source register
(SOURCE REG), refer to the table Table A-51 on page A-17.
ADSP-218x DSP Instruction Set Reference
4-117
Move Instructions
Data Memory Read (Direct Address)
Syntax
reg = DM ( <addr> )
;
Permissible registers
AX0
MX0
SI
AX1
MX1
SE
AY0
MY0
SR1
AY1
MY1
SR0
AR
MR2
I0-I7
MR1
M0-M7
MR0
L0-L7
SB
PX
ASTAT
MSTAT
IMASK
ICNTL
CNTR
OWRCNTR (write only)
RX0
RX1
TX0
TX1
IFC (write only)
Example
SI = DM(ad_port0);
Description
The Read instruction moves the contents of the data memory location to
the destination register. The addressing mode is direct addressing (designated by an immediate address value or by a label). The data memory
address is stored directly in the instruction word as a full 14-bit field. The
contents of the source are always right-justified in the destination register
after the read (bit 0 maps to bit 0).
Note that whenever MR1 is loaded with data, it is sign-extended into MR2.
Status Generated
No status bits affected.
Instruction Format
Data Memory Read (Direct Address), Instruction Type 3:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
1
4-118
0
0
0
RGP
8
7
ADDR
ADSP-218x DSP Instruction Set Reference
6
5
4
3
2
REG
1
0
Instruction Set
ADDR
contains the direct address to the source location in Data Memory.
To choose the source register group (RGP) and the source register (REG),
refer to the table Table A-51 on page A-17.
ADSP-218x DSP Instruction Set Reference
4-119
Move Instructions
Data Memory Read (Indirect Address)
Syntax
Permissible dregs
AX0
MX0
AX1
MX1
AY0
MY0
AY1
MY1
AR
MR2
MR1
MR0
dreg = DM (
SI
SE
SR1
SR0
I0
I1
M0
’
) ;
M1
I2
M2
I3
M3
I4
M4
I5
M5
I6
M6
I7
M7
Example
AY0 = DM (I3, M1);
Description
The Data Memory Read Indirect instruction moves the contents of the
data memory location to the destination register. The addressing mode is
register indirect with post-modify. For linear (non-circular) indirect
addressing, the L register corresponding to the I register being used must
be set to zero. The contents of the source are always right-justified in the
destination register after the read (bit 0 maps to bit 0).
4-120
ADSP-218x DSP Instruction Set Reference
Instruction Set
Status Generated
No status bits affected.
Instruction Format
ALU/MAC operation with Data Memory Read, Instruction Type 4:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
0
0
DREG
1
1
G 0
0
AMF
0
0
0
0
6
5
4
3
I
2
1
0
M
specifies the ALU or MAC operation to be performed in parallel with
the Data Memory Read. In this case, AMF = 00000, indicating a no-operation for the ALU/MAC function.
AMF
To choose a data register, refer to the table “DREG Selection Codes” on
page A-12.
specifies which Data Address Generator the I and M registers are selected
from. These registers must be from the same DAG as separated by the gray
bar above. I specifies the indirect address pointer (I register). M specifies
the modify register (M register).
G
See Also
• “DAG Selection Codes” on page A-15
• “Index Register Selection Codes” on page A-15
• “Modify Register Selection Codes” on page A-16
ADSP-218x DSP Instruction Set Reference
4-121
Move Instructions
Program Memory Read (Indirect Address)
Syntax
Permissible dregs
AX0
MX0
AX1
MX1
AY0
MY0
AY1
MY1
AR
MR2
MR1
MR0
dreg = PM (
SI
SE
SR1
SR0
I4
I5
M4
’
);
M5
I6
M6
I7
M7
Example
MX1 = PM (I6, M5);
Description
The Program Memory Read Indirect instruction moves the contents of the
program memory location to the destination register. The addressing
mode is register indirect with post-modify. For linear (for example,
non-circular) indirect addressing, the L register corresponding to theI register used must be set to zero. The 16 most significant bits of the Program
Memory Data bus (PMD23-8) are loaded into the destination register, with
bit PMD8 lining up with bit 0 of the destination register (right-justification). If the destination register is less than 16 bits wide, the most
significant bits are dropped. Bits PMD7-0 are always loaded into the PX register. You may ignore these bits or read them out on a subsequent cycle.
Status Generated
4-122
ADSP-218x DSP Instruction Set Reference
Instruction Set
No status bits affected.
Instruction Format
ALU/MAC operation with Data Memory Read, Instruction Type 4:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
0
0
DREG
1
0
1
0
0
AMF
0
0
0
0
6
5
4
3
I
2
1
0
M
specifies the ALU or MAC operation to be performed in parallel with
the Data Memory Read. In this case, AMF = 00000, indicating a no-operation for the ALU/MAC function.
AMF
To choose a data register, refer to the table “DREG Selection Codes” on
page A-12.
specifies the indirect address pointer (I register). M specifies the modify
register (M register).
I
See Also
• “Index Register Selection Codes” on page A-15
• “Modify Register Selection Codes” on page A-16
ADSP-218x DSP Instruction Set Reference
4-123
Move Instructions
Data Memory Write (Direct Address)
Syntax
DM ( <addr> )
Permissible registers
AX0
MX0
SI
AX1
MX1
SE
AY0
MY0
SR1
AY1
MY1
SR0
AR
MR2
I0-I7
MR1
M0-M7
MR0
L0-L7
= reg;
SB
PX
ASTAT
MSTAT
SSTAT (read only)
IMASK
ICNTL
CNTR
RX0
RX1
TX0
TX1
Example
DM(cntl_port0) = AR;
Description
Moves the contents of the source register to the data memory location
specified in the instruction word. The addressing mode is direct addressing (designated by an immediate address value or by a label). The data
memory address is stored directly in the instruction word as a full 14-bit
field. Whenever a register that is less than 16 bits in length is written to
memory, the value written is either sign-extended to the left if the source
is a signed value, or zero-filled to the left if the source is an unsigned
value. The unsigned registers which are zero-filled to the left are: I0
through I7, L0 through L7, CNTR, PX, ASTAT, MSTAT, SSTAT, IMASK, and
ICNTL. All other registers are sign-extended to the left.
The contents of the source are always right-justified in the destination
location after the write (bit 0 maps to bit 0).
Note that whenever MR1 is loaded with data, it is sign-extended into MR2.
Status Generated
4-124
ADSP-218x DSP Instruction Set Reference
Instruction Set
No status bits affected.
Instruction Format
Data Memory Read (Direct Address), Instruction Type 3:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
1
0
0
1
RGP
ADDR
8
7
6
5
4
3
2
1
0
REG
contains the direct address of the destination location in Data
Memory.
ADDR
To choose the source register group (RGP) and the source register (REG),
refer Table A-51 on page A-17.
ADSP-218x DSP Instruction Set Reference
4-125
Move Instructions
Data Memory Write (Indirect Address)
Syntax
Permissible dregs
AX0
MX0
AX1
MX1
AY0
MY0
AY1
MY1
AR
MR2
MR1
MR0
SI
SE
SR1
SR0
DM (
I0
I1
data:
M0
’
M1
I2
M2
I3
M3
I4
M4
I5
M5
I6
M6
I7
M7
) =
dreg
;
<data>
<constant>
Example
DM (I2, M0)= MR1;
Description
The Data Memory Write Indirect instruction moves the contents of the
source to the data memory location specified in the instruction word. The
immediate data may be a constant.
4-126
ADSP-218x DSP Instruction Set Reference
Instruction Set
The addressing mode is register indirect with post-modify. For linear (for
example, non-circular) indirect addressing, the L register corresponding to
the I register used must be set to zero. When a register of less than 16 bits
is written to memory, the value written is sign-extended to form a 16-bit
value. The contents of the source are always right-justified in the destination location after the write (bit 0 maps to bit 0).
Status Generated
No status bits affected.
Instruction Format
ALU/MAC operation with Data Memory Write, Instruction Type 4:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
0
0
DREG
1
1
G 1
0
AMF
0
0
0
0
6
5
4
3
2
1
I
0
M
Data Memory Write, Immediate Data, Instruction Type 2:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
1
0
1
8
7
6
5
4
3
G Data
2
1
I
0
M
specifies the ALU or MAC operation to be performed in parallel with
the Data Memory Write. In this case, AMF = 00000, indicating a no-operation for the ALU/MAC function.
AMF
Data
represents the actual 16-bit value.
To choose a data register (DREG), refer to the table “DREG Selection
Codes” on page A-12.
specifies which Data Address Generator (DAG) the I and M registers are
selected from. These registers must be from the same DAG as separated by
the gray bar above. I specifies the indirect address pointer (I register). M
specifies the modify register (M register).
G
ADSP-218x DSP Instruction Set Reference
4-127
Move Instructions
See Also
• “DAG Selection Codes” on page A-15
• “Index Register Selection Codes” on page A-15
• “Modify Register Selection Codes” on page A-16
4-128
ADSP-218x DSP Instruction Set Reference
Instruction Set
Program Memory Write (Indirect Address)
Syntax
PM (
I4
,
M4
I5
M5
I6
M6
I7
M7
)
=
dreg;
Permissible dregs
AX0
MX0
SI
AX1
MX1
SE
AY0
MY0
SR1
AY1
MY1
SR0
AR
MR2
MR1
MR0
Example
PM (I6, M5) = AR;
Description
The Program Memory Write Indirect instruction moves the contents of
the source to the program memory location specified in the instruction
word. The addressing mode is register indirect with post-modify. For linear (non-circular) indirect addressing, the L register corresponding to the I
ADSP-218x DSP Instruction Set Reference
4-129
Move Instructions
register used must be set to zero. The 16 most significant bits of the Program Memory Data bus (PMD23-8) are loaded from the source register, with
bit PMD8 aligned with bit 0 of the source register (right justification). The 8
least significant bits of the Program Memory Data bus (PMD7-0) are loaded
from the PX register. Whenever a source register of length less than 16 bits
is written to memory, the value written is sign-extended to form a 16-bit
value.
Status Generated
No status bits affected.
Instruction Format
ALU / MAC Operation with Program Memory Write, Instruction Type
5:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
0
0
DREG
1
0
1
1
0
AMF
0
0
0
0
6
5
4
3
2
I
1
0
M
AMF specifies the ALU or MAC operation to be performed in parallel with
the Program Memory Write. In this case, AMF = 00000, indicating a
no-operation for the ALU / MAC function.
To choose a data register (DREG), refer to the table “DREG Selection
Codes” on page A-12.
specifies the indirect address pointer (I register). M specifies the modify
register (M register).
I
See Also
• “Index Register Selection Codes” on page A-15
• “Modify Register Selection Codes” on page A-16
4-130
ADSP-218x DSP Instruction Set Reference
Instruction Set
IO Space Read/Write
Syntax
IO (<addr>) = dreg ;
I/O write
dreg = IO (<addr>) ;
I/O read
<addr>
is an 11-bit direct address value between 0 and 2047
Permissible dregs
AX0
MX0
SI
AX1
MX1
SE
AY0
MY0
SR1
AY1
MY1
SR0
AR
MR2
MR1
MR0
Example
IO(23) = AX0;
MY1 = IO(2047);
Description
The I/O space read and write instructions are used to access the
ADSP-218x’s I/O memory space. These instructions move data between
the processor data registers and the I/O memory space.
Status Generated
ADSP-218x DSP Instruction Set Reference
4-131
Move Instructions
No status bits affected.
Instruction Format
I/O Memory Space Read/Write, Instruction Type 29:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
0
0
0
1
8
7
6
5
D ADDR
4
3
2
1
0
DREG
contains the 11-bit direct address of the source or destination location in I/O Memory Space.
ADDR
To choose a data register (DREG), refer to the table “DREG Selection
Codes” on page A-12.
D
specifies the direction of the transfer (0=read, 1=write).
4-132
ADSP-218x DSP Instruction Set Reference
Instruction Set
Program Flow Instructions
The Program Flow instructions are:
• “JUMP” on page 4-134
• “CALL” on page 4-136
• “JUMP or CALL on Flag In Pin” on page 4-138
• “Modify Flag Out Pin” on page 4-140
• “RTS (Return from Subroutine)” on page 4-142
• “RTI (Return from Interrupt)” on page 4-144
• “Do Until” on page 4-146
• “Idle” on page 4-149
ADSP-218x DSP Instruction Set Reference
4-133
Program Flow Instructions
JUMP
Syntax
[IF
cond
]
JUMP
(I4)
;
(I5)
(I6)
(I7)
<addr>
Permissible conds
EQ
NE
GT
GE
LT
LE
NEG
POS
AV
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
IF NOT CE JUMP top_loop;
/* CNTR is decremented */
Description
Test the optional condition and, if true, perform the specified jump. If the
condition is not true then perform a no-operation. Omitting the condition performs the jump unconditionally. The JUMP instruction causes
program execution to continue at the effective address specified by the
instruction. The addressing mode may be direct or register indirect.
For direct addressing (using an immediate address value or a label), the
program address is stored directly in the instruction word as a full 14-bit
field. For register indirect jumps, the selected I register provides the
address; it is not post-modified in this case.
4-134
ADSP-218x DSP Instruction Set Reference
Instruction Set
If JUMP is the last instruction inside a DO UNTIL loop, you must ensure that
the loop stacks are properly handled. If NOT CE is used as the condition,
execution of the JUMP instruction decrements the processor’s counter (CNTR
register).
Status Generated
No status bits affected.
Instruction Format
Conditional JUMP Direct, Instruction Type 10:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
1
1
0
8
7
6
5
4
ADDR
3
2
1
0
1
0
COND
Conditional JUMP Indirect, Instruction Type 19:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
0
0
I
I
0
0
0
1
0
1
1
0
0
0
0
0
0
0
6
5
4
3
2
0
0
COND
specifies the I register (Indirect Address Pointer).
ADDR:
Immediate jump address
COND:
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “Index Register Selection Codes” on page A-15
ADSP-218x DSP Instruction Set Reference
4-135
Program Flow Instructions
CALL
Syntax
[IF
cond
] CALL
(I4)
;
(I5)
(I6)
(I7)
<addr>
Permissible conds
EQ
NE
GT
GE
LT
LE
NEG
POS
AV
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
IF AV CALL scale_down;
Description
Test the optional condition and, if true, then perform the specified call. If
the condition is not true then perform a no-operation. Omitting the condition performs the call unconditionally. The CALL instruction is intended
for calling subroutines. CALL pushes the PC stack with the return address
and causes program execution to continue at the effective address specified
by the instruction. The addressing modes available for the CALL instruction are direct or register indirect.
4-136
ADSP-218x DSP Instruction Set Reference
Instruction Set
For direct addressing (using an immediate address value or a label), the
program address is stored directly in the instruction word as a full 14-bit
field. For register indirect jumps, the selected I register provides the
address; it is not post-modified in this case.
If CALL is the last instruction inside a DO UNTIL loop, you must ensure that
the loop stacks are properly handled.
Status Generated
No status bits affected.
Instruction Format
Conditional JUMP Direct, Instruction Type 10:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
1
1
1
8
7
6
5
4
ADDR
3
2
1
0
1
0
COND
Conditional JUMP Indirect, Instruction Type 19:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
0
0
0
I
0
1
COND
I
0
0
0
1
0
1
1
0
0
0
0
0
0
0
2
specifies the I register (Indirect Address Pointer).
ADDR:
Immediate jump address
COND:
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “Index Register Selection Codes” on page A-15
ADSP-218x DSP Instruction Set Reference
4-137
Program Flow Instructions
JUMP or CALL on Flag In Pin
Syntax
IF
FLAG_IN
JUMP
NOT FLAG_IN
CALL
<addr>
;
Example
IF FLAG_IN JUMP service_proc_three;
Description
Test the condition of the FI pin of the processor and, if set to one, perform the specified jump or call. If FI is zero then perform a no-operation.
Omitting the flag in condition reduces the instruction to a standard JUMP
or CALL.
The JUMP instruction causes program execution to continue at the address
specified by the instruction. The addressing mode for the JUMP on FI must
be direct.
The CALL instruction is intended for calling subroutines. CALL pushes the
PC stack with the return address and causes program execution to continue at the address specified by the instruction. The addressing mode for
the CALL on FI must be direct.
If JUMP or CALL is the last instruction inside a DO UNTIL loop, you must
ensure that the loop stacks are properly handled.
For direct addressing (using an immediate address value or a label), the
program address is stored directly in the instruction word as a full 14-bit
field.
Status Generated
No status bits affected.
4-138
ADSP-218x DSP Instruction Set Reference
Instruction Set
Instruction Format
Conditional JUMP or CALL on Flag In Direct Instruction Type 27:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
S:
0
0
0
0
0
1
1
8
7
6
5
4
3
2
1
0
Address
Addr FIC
^ 12 LSBs
^ 2 MSBs
Specifies JUMP (0) or CALL (1)
FIC:
S
Latched state of FI pin
See Also
• “Jump and Call Codes” on page A-18
• “FI Condition Codes” on page A-14
ADSP-218x DSP Instruction Set Reference
4-139
Program Flow Instructions
Modify Flag Out Pin
Syntax
[ IF cond ]
SET
FLAG_OUT
RESET
FL0
TOGGLE
FL1
[,...];
FL2
Example
IF MV SET FLAG_OUT, RESET FL1;
Description
Evaluate the optional condition and if true, set to one, reset to zero, or
toggle the state of the specified flag output pin(s). Otherwise perform a
no-operation and continue with the next instruction. Omitting the condition performs the operation unconditionally. Multiple flags may be
modified by including multiple clauses, separated by commas, in a single
instruction. This instruction does not directly alter the flow of your program—it is provided to signal external devices.
Note that the FO pin is specified by FLAG_OUT in the instruction syntax.
The following flag outputs are present on the ADSP-218x processor: FO,
FL0, FL1, FL2
Status Generated
No status bits affected.
Instruction Format
4-140
ADSP-218x DSP Instruction Set Reference
Instruction Set
Flag Out Mode Control Instruction Type 28:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
0
0
1
0
0
0
0
0
FO
8
FO
7
FO
6
5
4
FO
3
2
1
0
COND
^ FL2 ^ FL1 ^ FL0 ^ FLAG_OUT
FO:
Operation to perform on flag output pin
COND:
Condition code
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
• “FO Condition Codes” on page A-14
ADSP-218x DSP Instruction Set Reference
4-141
Program Flow Instructions
RTS (Return from Subroutine)
Syntax
[IF cond ] RTS ;
Permissible conds
EQ
NE
GT
GE
LT
LE
NEG
POS
AV
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
IF LE RTS ;
Description
Test the optional condition and, if true, then perform the specified return.
If the condition is not true then perform a no-operation. Omitting the
condition performs the return unconditionally. RTS executes a program
return from a subroutine. The address on top of the PC stack is popped
and is used as the return address. The PC stack is the only stack popped.
If RTS is the last instruction inside a DO UNTIL loop, you must ensure that
the loop stacks are properly handled.
Status Generated
No status bits affected.
Instruction Format
4-142
ADSP-218x DSP Instruction Set Reference
Instruction Set
Conditional Return, Instruction Type 20:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
0
0
0
0
0
0
COND
0
0
COND:
0
1
0
1
0
0
0
0
0
0
0
0
2
1
0
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
ADSP-218x DSP Instruction Set Reference
4-143
Program Flow Instructions
RTI (Return from Interrupt)
Syntax
[IF
cond ] RTI;
Permissible conds
EQ
NE
GT
GE
LT
LE
NEG
POS
AV
NOT AV
AC
NOT AC
MV
NOT MV
NOT CE
Example
IF
MV
RTI ;
Description
Test the optional condition and, if true, then perform the specified return.
If the condition is not true then perform a no-operation. Omitting the
condition performs the return unconditionally. RTI executes a program
return from an interrupt service routine. The address on top of the PC
stack is popped and is used as the return address. The value on top of the
status stack is also popped, and is loaded into the arithmetic status
(ASTAT), mode status (MSTAT) and the interrupt mask (IMASK) registers.
If RTI is the last instruction inside a DO UNTIL loop, you must ensure that
the loop stacks are properly handled.
Status Generated
No status bits affected.
Instruction Format
4-144
ADSP-218x DSP Instruction Set Reference
Instruction Set
Conditional Return, Instruction Type 20:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
0
0
0
0
0
1
COND
0
0
COND:
0
1
0
1
0
0
0
0
0
0
0
0
2
1
0
Condition
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Status Condition Codes” on page A-11
ADSP-218x DSP Instruction Set Reference
4-145
Program Flow Instructions
Do Until
Syntax
DO <addr> [UNTIL term];
Permissible terms
EQ
NE
GT
GE
LT
LE
NEG
POS
AV
NOT AV
AC
NOT AC
MV
NOT MV
CE
FOREVER
Example
DO loop_label
UNTIL CE;
/* CNTR is decremented each pass through loop */
Description
sets up looping circuitry for zero-overhead looping. The program
loop begins at the program instruction immediately following the DO
instruction, ends at the address designated in the instruction and repeats
execution until the specified termination condition is met (if one is specified) or repeats in an infinite loop (if none is specified). The termination
condition is tested during execution of the last instruction in the loop, the
status having been generated upon completion of the previous instruction.
The address (<addr>) of the last instruction in the loop is stored directly
in the instruction word.
DO UNTIL
If CE is used for the termination condition, the processor’s counter (CNTR
register) is decremented once for each pass through the loop.
When the DO instruction is executed, the address of the last instruction is
pushed onto the loop stack along with the termination condition and the
current program counter value plus 1 is pushed onto the PC stack.
4-146
ADSP-218x DSP Instruction Set Reference
Instruction Set
Any nesting of DO loops continues the process of pushing the loop and PC
stacks, up to the limit of the loop stack size (4 levels of loop nesting) or of
the PC stack size (16 levels for subroutines plus interrupts plus loops).
With either or both the loop or PC stacks full, a further attempt to perform the DO instruction sets the appropriate stack overflow bit and
performs a no-operation.
Status Generated
(See Table 4-11 on page 4-30 for register notation)
Instruction Format
ASTAT:
Not affected.
SSTAT:
7
6
5
4
3
2
1
0
LSO
LSE
SSO
SSE
CSO
CSE
PSO
PSE
*
0
–
–
–
–
*
0
LSO
Loop Stack Overflow: set if the loop stack overflows; otherwise not affected.
LSE
Loop Stack Empty: always cleared (indicating loop stack not empty).
PSO
PC Stack Overflow: set if the PC stack overflows; otherwise not affected.
PSE
PC Stack Empty: always cleared (indicating PC stack not empty).
Do Until, Instruction Type 11:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
1
0
1
Addr
8
7
6
5
4
3
2
1
0
TERM
ADSP-218x DSP Instruction Set Reference
4-147
Program Flow Instructions
specifies the address of the last instruction in the loop. In the
Instruction Syntax, this field may be a program label or an immediate
address value.
ADDR
TERM
specifies the termination condition, as shown below:
TERM
Syntax
Condition Tested
0000
NE
Not Equal to Zero
0001
EQ
Equal Zero
0010
LE
Less Than or Equal to Zero
0011
GT
Greater Than Zero
0100
GE
Greater Than or Equal to Zero
0101
LT
Less Than Zero
0110
NOT AV
Not ALU Overflow
0111
AV
ALU Overflow
1000
NOT AC
Not ALU Carry
1001
AC
ALU Carry
1010
POS
X Input Sign Positive
1011
NEG
X Input Sign Negative
1100
NOT MV
Not MAC Overflow
1101
MV
MAC Overflow
1110
CE
Counter Expired
1111
FOREVER
Always
4-148
ADSP-218x DSP Instruction Set Reference
Instruction Set
Idle
Syntax
IDLE ;
IDLE (n);
/* slow idle * /
Description
causes the processor to wait indefinitely in a low-power state, waiting
for interrupts. When an interrupt occurs it is serviced and execution continues with the instruction following IDLE. Typically this next instruction
is a JUMP back to IDLE, implementing a low-power standby loop.
IDLE
on
or
as the last instruction in a
L Note theloop,restrictions
detailed in the ADSP-218x DSP Hardware Reference
JUMP
IDLE
DO
UNTIL
Manual, Chapter 3, “Program Control.”
is a special version of IDLE that slows the processor’s internal
clock signal to further reduce power consumption. The reduced clock frequency, a programmable fraction of the normal clock rate, is specified by a
selectable divisor n given in the instruction: n = 16, 32, 64, or 128. The
instruction leaves the processor fully functional, but operating at the
slower rate during execution of the IDLE (n) instruction. While it is in
this state, the processor’s other internal clock signals (such as SCLK, CLKOUT, and the timer clock) are reduced by the same ratio.
IDLE (n)
When the IDLE (n) instruction is used, it slows the processor’s internal
clock and thus its response time to incoming interrupts—the 1-cycle
response time of the standard IDLE state is increased by n, the clock divisor. When an enabled interrupt is received, the ADSP-218x remains in the
IDLE state for up to a maximum of n CLKIN cycles (where n = 16, 32, 64,
or 128) before resuming normal operation.
When the IDLE (n) instruction is used in systems that have an externally
generated serial clock, the serial clock rate may be faster than the processor’s reduced internal clock rate. Under these conditions, interrupts must
ADSP-218x DSP Instruction Set Reference
4-149
Program Flow Instructions
not be generated at a faster rate than can be serviced, due to the additional
time the processor takes to come out of the IDLE state (a maximum of n
CLKIN cycles).
Serial port autobuffering continues during IDLE without affecting the idle
state.
Status Generated
No status bits affected.
Instruction Format
Idle, Instruction Type 31:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
DV
DV:
Clock divisor
0
0
0
0
0
1
0
1
0
0
0
0
0
Slow Idle, Instruction Type 31:
0
0
0
0
1
0
1
0
0
0
0
0
0
See Also
• “Slow Idle Divisor Codes” on page A-14
4-150
ADSP-218x DSP Instruction Set Reference
Instruction Set
MISC Instructions
MISC instructions are:
• “Stack Control” on page 4-152
• “Program Memory Overlay Register Update” on page 4-162
• “Data Memory Overlay Register Update” on page 4-165
• “Modify Address Register” on page 4-168
• “No Operation” on page 4-170
ADSP-218x DSP Instruction Set Reference
4-151
MISC Instructions
Stack Control
Syntax
[
PUSH
POP
STS ]
[,POP CNTR]
[, POP PC]
[, POP LOOP] ;
Example
POP CNTR, POP PC, POP LOOP;
/* C-style break instruction */
DO MYLOOP UNTIL FOREVER;
....
IF FLAG_IN JUMP MYLOOP+1;
/* Leave the loop */
....
MYLOOP: <ANY INSTRUCTION>
POP PC, POP LOOP;
/* Pop PC and loop stack */
/* The loop counter stack must be popped whenever a
counter based loop is aborted in this way
*/
Description
Stack Control pushes or pops the designated stack(s). The entire instruction executes in one cycle regardless of how many stacks are specified.
The PUSH STS (Push Status Stack) instruction increments the status stack
pointer by one to point to the next available status stack location; and
pushes the arithmetic status (ASTAT), mode status (MSTAT), and interrupt
mask register (IMASK) onto the processor’s status stack. Note that the PUSH
STS operation is executed automatically whenever an interrupt service routine is entered.
4-152
ADSP-218x DSP Instruction Set Reference
Instruction Set
Any POP pops the value on the top of the designated stack and decrements
the same stack pointer to point to the next lowest location in the stack.
POP STS causes the arithmetic status (ASTAT), mode status (MSTAT), and
interrupt mask (IMASK) to be popped into these same registers. This also
happens automatically whenever a return from interrupt (RTI) is executed.
POP CNTR causes the counter stack to be popped into the down counter.
When the loop stack or PC stack is popped (with POP LOOP or POP PC,
respectively), the information is lost. Returning from an interrupt (RTI) or
subroutine (RTS) also pops the PC stack automatically.
Status Generated
(See Table 4-11 on page 4-30 for register notation).
SSTAT
7
6
5
4
3
2
1
0
LSO
LSE
SSO
SSE
CSO
CSE
PSO
PSE
–
*
*
*
–
*
–
*
PSE
PC Stack Empty: set if a pop results in an empty program counter stack; cleared
otherwise.
CSE
Counter Stack Empty: set if a pop results in an empty counter stack; cleared otherwise.
SSE
Status Stack Empty: for PUSH STS, this bit is always cleared (indicating status stack
not empty). For POP STS, SSE is set if the pop results in an empty status stack;
cleared otherwise.
SSO
Status Stack Overflow: for PUSH STS set if the status stack overflows; otherwise not
affected.
LSE
Loop Stack Empty: set if a pop results in an empty loop stack; cleared otherwise.
ADSP-218x DSP Instruction Set Reference
4-153
MISC Instructions
Note that once any Stack Overflow occurs, the corresponding stack overflow bit is set in SSTAT, and this bit stays set indicating there has been loss
of information. Once set, the stack overflow bit can only be cleared by
resetting the processor.
Instruction Format
Stack Control, Instruction Type 26:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0 0 0 Iq
PC Stack Control
Lp:
Loop Stack Control
Cp:
Counter Stack Control
Spp:
Status Stack Control
Iq:
10 = Disable Ints, 11 = Enable Ints
• “Mode Control Codes” on page A-5
4-154
ADSP-218x DSP Instruction Set Reference
2
1
Pp Lp Cp Spp
Pp:
See Also
3
0
Instruction Set
TOPPCSTACK
A special version of the register-to-register Move instruction, Type 17, is
provided for reading and popping or writing and pushing the top value of
the PC stack. the normal POP PC instruction does not save the value
popped from the stack.
To save this value into a register, use the following special instruction.
reg = TOPPCSTACK;
/* pop PC stack into reg */
/* toppcstack may also be lowercase */
The PC stack is also popped by this instruction, after a one-cycle delay.
An NOP should usually be placed after the special instruction, to allow the
pop to occur properly:
reg = TOPPCSTACK;
NOP;
/* allow pop to occur correctly */
There us no standard PUSH PC stack instruction. To push a specific value
onto the PC stack, therefore, use the following special instruction.
TOPPCSTACK = reg;
/*push reg contents onto PC stack */
The stack is pushed immediately in the same cycle.
that
may not be used as a register in any other
L Note
instruction type.
the PC stack width is 14 bits, be sure that registers that are
L Because
pushed onto the PC stack via the
instruction are
TOPPCSTACK
TOPPCSTACK = reg
14 bits or less to order to avoid loss of data. The 14 MSBs from a
16 bit register are written to the PC stack. The upper 2 bits of the
16 bit value are discarded.
ADSP-218x DSP Instruction Set Reference
4-155
MISC Instructions
Example
AX0 = TOPPCSTACK;
/* pop PC stack into AX0 */
NOP;
TOPPCSTACK = I7;
/* push contents of I7 onto PC stack */
Use only the following registers in the TOPPCSTACK instruction:
ALU, MAC and Shifter Registers
DAG Registers
AX0
MX0
SI
I0
I4
M0
M4
L0
L4
AX1
MX1
SE
I1
I5
M1
M5
L1
L5
AY0
MY0
SR1
I2
I6
M2
M6
L2
L6
AY1
MY1
SR0
I3
I7
M3
M7
L3
L7
AR
MR2
MR1
MR0
MX0
There are several restrictions on the use of the special TOPPCSTACK instructions which are described in the ADSP-218x DSP Hardware Reference
Manual, Chapter 3, “Program Control.”
Instruction Format
TOPPCSTACK = reg
Internal Data Move, Instruction Type 17:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
1
1
0
1
0
0
0
0
1
1
8
7
6
5
4
3
SRC
RGP
1
1
1
1
SOURCE
REG
2
1
0
To choose the source register group (SRC RGP) and the source register
(SOURCE REG), refer to the table “Register Selection Codes” on page A-17.
4-156
ADSP-218x DSP Instruction Set Reference
Instruction Set
reg = TOPPCSTACK
Internal Data Move, Instruction Type 17:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
0
1
DEST
REG
0
0
0
1
1
0
1
0
0
0
0
DST
RGP
1
6
5
4
3
2
1
0
1
1
1
1
To choose the destination register group (DST RGP) and the destination
register (DEST REG), refer to the table “Register Selection Codes” on
page A-17.
ADSP-218x DSP Instruction Set Reference
4-157
MISC Instructions
Mode Control
Syntax
ENA
BIT_REV
DIS
AV_LATCH
[, ...] ;
AR_SAT
SEC_REG
G_MODE
M_MODE
TIMER
Example
DIS AR_SAT, ENA M_MODE;
Description
Enables (ENA) or disables (DIS) the designated processor mode. The corresponding mode status bit in the mode status register (MSTAT) is set for ENA
mode and cleared for DIS mode. At reset, MSTAT is set to zero, meaning
that all modes are disabled. Any number of modes can be changed in one
cycle with this instruction. Multiple ENA or DIS clauses must be separated
by commas.
4-158
ADSP-218x DSP Instruction Set Reference
Instruction Set
MSTAT Bits
Description
0
SEC_REG
Alternate Register Data Bank
1
BIT_REV
Bit-Reverse Mode on Address Generator #1
2
AV_LATCH
ALU Overflow Status Latch Mode
3
AR_SAT
ALU AR Register Saturation Mode
4
M_MODE
MAC Result Placement Mode
5
TIMER
Timer Enable
6
G_MODE
Enables GO Mode
The data register bank select bit (SEC_REG) determines which set of data
registers is currently active (0=primary, 1=secondary).
The bit-reverse mode bit (BIT_REV), when set to 1, causes addresses generated by Data Address Generator #1 to be output in bit reversed order.
The ALU overflow latch mode bit (AV_LATCH), when set to 1, causes the AV
bit in the arithmetic status register to stay set once an ALU overflow
occurs. In this mode, if an ALU overflow occurs, the AV bit is set and
remains set even if subsequent ALU operations do not generate overflows.
The AV bit can only be cleared by writing a zero into it directly over the
DMD bus.
The AR saturation mode bit, (AR_SAT), when set to 1, causes the AR register
to saturate if an ALU operation causes an overflow, as described in the
ADSP-218x DSP Hardware Reference Manual, Chapter 2, “Computational
Units.”
The MAC result placement mode (M_MODE) determines whether or not the
left shift is made between the multiplier product and the MR register.
Setting the Timer Enable bit (TIMER) starts the timer decrementing logic.
Clearing this bit halts the timer.
ADSP-218x DSP Instruction Set Reference
4-159
MISC Instructions
The GO mode (G_MODE) allows an ADSP-218x DSP to continue executing
instructions from internal memory (if possible) during a bus grant. The GO
mode allows the processor to run; only if an external memory access is
required does the processor halt, waiting for the bus to be released.
Instruction Format
Mode Control, Instruction Type 18:
23 22 21 20 19 18 17 16 15 14 13
0
0
0
0
1
1
0
0
TI
12 11 10 9 8
MM
AS
OL
7
6
BR
5
SR
4
3
2
GM
TI:
Timer Enable
MM:
Multiplier Placement
AS:
AR Saturation Mode Control
OL:
ALU Overflow Latch Mode Control
BR:
Bit Reverse Mode Control
SR:
Secondary Register Bank Mode
GM:
GO Mode
See Also
• IF Condition Codes Table 4-9 on page 4-24
• “Type 18: Mode Control” on page A-5
4-160
ADSP-218x DSP Instruction Set Reference
1 0
0 0
Instruction Set
Interrupt Enable and Disable
Syntax
ENA INTS ;
DIS INTS ;
Description
Interrupts are enabled by default at reset. Executing the DIS INTS instruction causes all interrupts (including the power down interrupt) to be
masked, without changing the contents of the IMASK register.
Executing the ENA INTS instruction allows all unmasked interrupts to be
serviced again.
that disabling interrupts does not affect serial port autoL Note
buffering or ADSP-218x DMA transfers (IDMA or BDMA). These
operations continue normally whether or not interrupts are
enabled.
Status Generated
No status bits affected.
Instruction Format
DIS INTS, Instruction Type 26:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0 0 0 1 0 0 0 0 0 0
ENA INTS, Instruction Type 26:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0 0 0 1 1 0 0 0 0 0
ADSP-218x DSP Instruction Set Reference
4-161
MISC Instructions
Program Memory Overlay Register Update
Syntax
PMOVLAY = <data>;
reg = PMOVLAY;
data:<constant>
Permissible dregs
Permissible regs
AX0
MX0
SI
SB
CNTR
AX1
MX1
SE
PX
OWRCNTR (write only)
AY0
MY0
SR1
ASTAT
RX0
AY1
MY1
SR0
MSTAT
RX1
AR
MR2
IMASK
TX0
MR1
ICNTL
TX1
MR0
I0-I7
IFC (write only)
M0-M7
DMOVLAY
L0-L7
Permissible constants:
4-162
1,2
ADSP-2184 and ADSP-2186 processors only
0,1,2
ADSP-2181, ADSP-2183, and ADSP-2185 processors only
0,1,2,4,5
ADSP-2187 and ADSP-2189 processors only
0,1,2,4,5,6,7
ADSP-2188 processor only
ADSP-218x DSP Instruction Set Reference
Instruction Set
Example
PMOVLAY = 5;
/* Write to pmovlay register */
/* Read from pmovlay register into ax0 register */
AX0 = PMOVLAY;
PMOVLAY = DMOVLAY;
PMOVLAY = DM(0x1234);
/* Write to PMOVLAY from DMOVLAY */
/* Write to PMOVLAY from data memory */
Description
The PMOVLAY write instruction switches the context of the hardware program memory overlay region to the specific region specified by the
permissible data value written to the PMOVLAY register. The PMOVLAY read
instruction moves the value from the PMOVLAY register into one of the permissible registers listed above.
Status Generated
No status bits affected.
Instruction Format
Read/Write Data Memory (Immediate Address), Instruction Type 3:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
1
0
0
D RGP
8
7
6
5
4
ADDR
3
2
1
0
1
0
REG
Load Non-data Register Immediate, Instruction Type 7:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
1
RGP
DATA
8
7
6
5
4
3
2
REG
ADSP-218x DSP Instruction Set Reference
4-163
MISC Instructions
Load Non-data Register Immediate, Instruction Type 17:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
1
1
0
1
0
0
0
0
DST
RGP
8
SRC
RGP
7
6
DEST
REG
5
4
3
2
1
0
SOURCE
REG
To choose the source register group (SRC RGP) and the source register
(SOURCE REG), refer to the table “Register Selection Codes” on page A-17.
To choose the destination register group (DST RGP) and the destination
register (DEST REG), refer to the table “Register Selection Codes” on
page A-17.
4-164
ADSP-218x DSP Instruction Set Reference
Instruction Set
Data Memory Overlay Register Update
Syntax
DMOVLAY = <data>;
reg = DMOVLAY;
data:<constant>
Permissible dregs
Permissible regs
AX0
MX0
SI
SB
CNTR
AX1
MX1
SE
PX
OWRCNTR (write only)
AY0
MY0
SR1
ASTAT
RX0
AY1
MY1
SR0
MSTAT
RX1
AR
MR2
IMASK
TX0
MR1
ICNTL
TX1
MR0
I0-I7
IFC (write only)
M0-M7
PMOVLAY
L0-L7
Permissible constants:
1,2
ADSP-2184 and ADSP-2186 processors only
0,1,2
ADSP-2181, ADSP-2183, and ADSP-2185 processors only
0,1,2,4,5
ADSP-2187 processors only
0,1,2,4,5,6,7
ADSP-2189 processors only
0,1,2,4,5,6,7,8
ADSP-2188 processor only
ADSP-218x DSP Instruction Set Reference
4-165
MISC Instructions
Example
DMOVLAY = 1;
/* Write to dmovlay register */
/* Read from dmovlay register into ax0 register */
AX0 = DMOVLAY;
DMOVLAY = PMOVLAY;
DM(0x0000) = DMOVLAY;
/* Write to DMOVLAY from PMOVLAY */
/* Write DMOVLAY to data memory */
Description
The DMOVLAY write instruction switches the context of the hardware data
memory overlay region to the specific region specified by the permissible
data value written to the DMOVLAY register. The DMOVLAY read instruction
moves the value from the DMOVLAY register into one of the permissible registers listed above.
Status Generated
No status bits affected.
Instruction Format
Read/Write Data Memory (Immediate Address), Instruction Type 3:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
1
0
0
D RGP
8
7
6
5
4
ADDR
3
2
1
0
1
0
REG
Load Non-data Register Immediate, Instruction Type 7:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
4-166
0
1
1
RGP
8
7
DATA
ADSP-218x DSP Instruction Set Reference
6
5
4
3
2
REG
Instruction Set
Load Non-data Register Immediate, Instruction Type 17:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
1
1
0
1
0
0
0
0
DST
RGP
8
SRC
RGP
7
6
DEST
REG
5
4
3
2
1
0
SOURCE
REG
To choose the source register group (SRC RGP) and the source register
(SOURCE REG), refer to the table “Register Selection Codes” on page A-17.
To choose the destination register group (DST RGP) and the destination
register (DEST REG), refer to the table “Register Selection Codes” on
page A-17.
ADSP-218x DSP Instruction Set Reference
4-167
MISC Instructions
Modify Address Register
Syntax
MODIFY
(
I0
I1
I2
I3
,
I4
I5
I6
I7
M0
M1
M2
M3
);
M4
M5
M6
M7
Example
MODIFY (I1, M1);
Description
Add the selected M register (Mn) to the selected I register (Im), then process
the modified address through the modulus logic with buffer length as
determined by the L register corresponding to the selected I register (Lm),
and store the resulting address pointer calculation in the selected I register. The I register is modified as if an indexed memory address were taking
place, but no actual memory data transfer occurs. For linear (for example,
non-circular) indirect addressing, the L register corresponding to the I register used must be set to zero.
The selection of the I and M registers is constrained to registers within the
same Data Address Generator: selection of I0-I3 in Data Address Generator #1 constrains selection of the M registers to M0-M3. Similarly, selection
of I4-I7 constrains the M registers to M4-M7.
Status Generated
4-168
ADSP-218x DSP Instruction Set Reference
Instruction Set
No status bits affected.
Instruction Format
Modify Address Register, Instruction Type 21:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3
0
0
0
0
1
0
0
1
0
0
0
0
0
0
0 0 0 0 0 G I
2 1
0
M
specifies which Data Address Generator is selected. The I and M registers
specified must be from the same DAG, separated by the gray bar above. I
specifies the I register (depends on which DAG is selected by the G bit). M
specifies the M register (depends on which DAG is selected by the G bit).
G
See Also
• “DAG Selection Codes” on page A-15
• “Index Register Selection Codes” on page A-15
• “Modify Register Selection Codes” on page A-16
ADSP-218x DSP Instruction Set Reference
4-169
MISC Instructions
No Operation
Syntax
NOP;
Description
No operation occurs for one cycle. Execution continues with the instruction following the NOP instruction.
Status Generated
No status bits affected.
Instruction Format
No operation, Instruction Type 30, as shown below:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
0
0
0
4-170
0
0
0
0
0
0
0
0
0
0
0
0
0
0 0 0 0 0 0 0 0 0
ADSP-218x DSP Instruction Set Reference
Instruction Set
Multifunction Instructions
Multifunction instructions are:
• “Computation With Memory Read” on page 4-172
• “Computation With Register-to-Register Move” on page 4-178
• “Computation With Memory Write” on page 4-183
• “Data and Program Memory Read” on page 4-188
• “ALU/MAC With Data and Program Memory Read” on
page 4-190
ADSP-218x DSP Instruction Set Reference
4-171
Multifunction Instructions
Computation With Memory Read
Syntax
<ALU>
<MAC>
<SHIFT>
, dreg =
DM (
PM (
I0
I1
I2
I3
,
M0
M1
M2
M3
I4
I5
I6
I7
,
M4
M5
M6
M7
I4
I5
I6
I7
,
M4
M5
M6
M7
Permissible dregs
AX0
MX0
SI
AX1
MX1
SE
AY0
MY0
SR0
AY1
MY1
SR1
AR
MR0
MR1
MR2
4-172
ADSP-218x DSP Instruction Set Reference
)
)
;
Instruction Set
Description
Perform the designated arithmetic operation and data transfer. The read
operation moves the contents of the source to the destination register. The
addressing mode when combining an arithmetic operation with a memory
read is register indirect with post-modify. For linear (for example, non-circular) indirect addressing, the L register corresponding to the I register
used must be set to zero. The contents of the source are always right-justified in the destination register.
The computation must be unconditional. All ALU, MAC and Shifter
operations are permitted except Shift Immediate and ALU DIVS and DIVQ
instructions.
The fundamental principle governing multifunction instructions is that
registers (and memory) are read at the beginning of the processor cycle
and written at the end of the cycle. The normal left-to-right order of
clauses (computation first, memory read second) is intended to imply this.
In fact, you may code this instruction with the order of clauses reversed.
The assembler produces a warning, but the results are identical at the
opcode level. If you turn off semantics checking in the assembler (using
the –s switch) the warning is not issued.
Because of the read-first, write-second characteristic of the processor,
using the same register as source in one clause and a destination in the
other is legal. The register supplies the value present at the beginning of
the cycle and is written with the new value at the end of the cycle.
ADSP-218x DSP Instruction Set Reference
4-173
Multifunction Instructions
For example,
(1) AR = AX0 + AY0, AX0 = DM (I0, M0);
is a legal version of this multifunction instruction and is not flagged by the
assembler. Reversing the order of clauses, as in
(2) AX0 = DM (I0, M0), AR = AX0 + AY0;
results in an assembler warning, but assembles and executes exactly as the
first form of the instruction. Note that reading example (2) from left to
right may suggest that the data memory value is loaded into AX0 and then
used in the computation, all in the same cycle. In fact, this is not possible.
The left-to-right logic of example (1) suggests the operation of the instruction more closely. Regardless of the apparent logic of reading the
instruction from left to right, the read-first, write-second operation of the
processor determines what actually happens.
Using the same register as a destination in both clauses, however, produces
an indeterminate result and should not be done. The assembler issues a
warning unless semantics checking is turned off. Regardless of whether or
not the warning is produced, however, this practice is not supported.
The following, therefore, is illegal and not supported, even though assembler semantics checking produces only a warning:
(3) AR = AX0 + AY0, AR = DM (I0, M0); Illegal!
Status Generated
(See Table 4-11 on page 4-30 for register notation)
All status bits are affected in the same way as for the single function versions of the selected arithmetic operation.
4-174
ADSP-218x DSP Instruction Set Reference
Instruction Set
<ALU> operation
ASTAT:
AZ
7
6
5
4
3
2
1
0
SS
MV
AQ
AS
AC
AV
AN
AZ
-
-
-
*
*
*
*
*
Set if result equals zero. Cleared otherwise.
AN
Set if result is negative. Cleared otherwise.
AV
Set if an overflow is generated. Cleared otherwise.
AC
Set if a carry is generated. Cleared otherwise.
AS
Affected only when executing the Absolute Value operation (ABS). Set if the
source operand is negative.
<MAC> operation
ASTAT
MV
7
6
5
4
3
2
1
0
SS
MV
AQ
AS
AC
AV
AN
AZ
-
*
-
-
-
-
-
-
Set if the accumulated product overflows the lower-order 32 bits of the MR
register. Cleared otherwise.
ADSP-218x DSP Instruction Set Reference
4-175
Multifunction Instructions
<SHIFT> operation
ASTAT
7
6
5
4
3
2
1
0
SS
MV
AQ
AS
AC
AV
AN
AZ
*
-
-
-
-
-
-
-
Affected only when executing the EXP operation; set if the source operand is
negative. Cleared if the number is positive.
SS
Instruction Format
ALU/MAC operation with Data Memory Read, Instruction Type 4:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
1
1
G 0
Z AMF
Yop
8
7
Xop
6
5
4
Dreg
3
2
I
1
0
M
ALU/MAC operation with Program Memory Read, Instruction Type 5:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
1
0
1
0
Z
AMF
Yop
8
Xop
7
6
5
4
3
Dreg
2
1
I
0
M
Shift operation with Data Memory Read, Instruction Type 12:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
1
0
0
1
G 0
SF
8
Xop
7
6
5
4
Dreg
3
2
I
1
0
M
Shift operation with Program Memory Read, Instruction Type 13:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
4-176
0
0
1
0
0
0
1
0
SF
Xop
8
7
6
Dreg
ADSP-218x DSP Instruction Set Reference
5
4
3
I
2
1
M
0
Instruction Set
Z:
Result register
Dreg:
Destination register
SF:
Shifter operation
AMF:
ALU/MAC operation
Yop:
Y operand
Xop:
X operand
G:
Data Address Generator
I:
Indirect address register
M:
Modify register
See Also
• “DREG Selection Codes” on page A-12
• “ALU/MAC Result Register Codes” on page A-22
• “Shifter Function Codes” on page A-18
• “DAG Selection Codes” on page A-15
• “Index Register Selection Codes” on page A-15
• “Modify Register Selection Codes” on page A-16
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
• “AMF Function Codes” on page A-9
ADSP-218x DSP Instruction Set Reference
4-177
Multifunction Instructions
Computation With Register-to-Register Move
Syntax
<ALU>
<MAC>
<SHIFT>
,dreg =dreg;
Permissible dregs
AX0
MX0
SI
AX1
MX1
SE
AY0
MY0
SR0
AY1
MY1
SR1
AR
MR0
MR1
MR2
Description
Perform the designated arithmetic operation and data transfer. The contents of the source are always right-justified in the destination register
after the read.
The computation must be unconditional. All ALU, MAC and Shifter
operations are permitted except Shift Immediate and ALU DIVS and DIVQ
instructions.
The fundamental principle governing multifunction instructions is that
registers (and memory) are read at the beginning of the processor cycle
and written at the end of the cycle. The normal left-to-right order of
4-178
ADSP-218x DSP Instruction Set Reference
Instruction Set
clauses (computation first, register transfer second) is intended to imply
this. In fact, you may code this instruction with the order of clauses
reversed. The assembler produces a warning, but the results are identical at
the opcode level. If you turn off semantics checking in the assembler (–s
switch) the warning is not issued.
Because of the read-first, write-second characteristic of the processor,
using the same register as source in one clause and a destination in the
other is legal. The register supplies the value present at the beginning of
the cycle and is written with the new value at the end of the cycle.
For example,
(1) AR = AX0 + AY0, AX0 = MR1;
is a legal version of this multifunction instruction and is not flagged by the
assembler. Reversing the order of clauses, as in
(2) AX0 = MR1, AR = AX0 + AY0;
results in an assembler warning, but assembles and executes exactly as the
first form of the instruction. Note that reading example (2) from left to
right may suggest that the MR1 register value is loaded into AX0 and then
AX0 is used in the computation, all in the same cycle. In fact, this is notpossible. The left-to-right logic of example (1) suggests the operation of
the instruction more closely. Regardless of the apparent logic of reading
the instruction from left to right, the read-first, write-second operation of
the processor determines what actually happens.
Using the same register as a destination in both clauses, however, produces
an indeterminate result and should not be done. The assembler issues a
warning unless semantics checking is turned off. Regardless of whether or
not the warning is produced, however, this practice is not supported.
ADSP-218x DSP Instruction Set Reference
4-179
Multifunction Instructions
The following, therefore, is illegal and not supported, even though assembler semantics checking produces only a warning:
(3) AR = AX0 + AY0, AR = MR1; Illegal!
Status Generated
(See Table 4-11 on page 4-30 for register notation)
All status bits are affected in the same way as for the single function versions of the selected arithmetic operation.
<ALU> operation
ASTAT:
7
6
5
4
3
2
1
0
SS
MV
AQ
AS
AC
AV
AN
AZ
-
-
-
*
*
*
*
*
AZ
Set if result equals zero. Cleared otherwise.
AN
Set if result is negative. Cleared otherwise.
AV
Set if an overflow is generated. Cleared otherwise.
AC
Set if a carry is generated. Cleared otherwise.
AS
Affected only when executing the Absolute Value operation (ABS). Set if the source
operand is negative.
4-180
ADSP-218x DSP Instruction Set Reference
Instruction Set
<MAC> operation
ASTAT:
7
6
5
4
3
2
1
0
SS
MV
AQ
AS
AC
AV
AN
AZ
-
*
-
-
-
-
-
-
Set if the accumulated product overflows the lower-order 32 bits of the MR register.
Cleared otherwise.
MV
<SHIFT> operation
ASTAT
7
6
5
4
3
2
1
0
SS
MV
AQ
AS
AC
AV
AN
AZ
*
-
-
-
-
-
-
-
Affected only when executing the EXP operation; set if the source operand
is negative. Cleared if the number is positive.
ALU/MAC operation with Data Register Move, Instruction Type 8:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
1
Z
AMF
Yop
Xop
8
7
6
5
Dreg dest
4
3
2
1
0
Dreg source
ADSP-218x DSP Instruction Set Reference
4-181
Multifunction Instructions
Shift operation with Data Register Move, Instruction Type 14:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
1
0
0
0
0
0
SF
8
Xop
7
6
5
Dreg dest
Z:
Result register
Dreg:
Data register
SF:
Shifter operation
AMF:
ALU/MAC operation
Yop:
Y operand
Xop:
X operand
See Also
• “DREG Selection Codes” on page A-12
• “ALU/MAC Result Register Codes” on page A-22
• “Shifter Function Codes” on page A-18
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
• “AMF Function Codes” on page A-9
4-182
ADSP-218x DSP Instruction Set Reference
4
3
2
1
Dreg source
0
Instruction Set
Computation With Memory Write
Syntax
DM (
I0
I1
I2
I3
,
I4
I5
I6
I7
PM (
I4
I5
I6
I7
M0
M1
M2
M3
)
= dreg,
<ALU>
<MAC>
<SHIFT>
;
M4
M5
M6
M7
,
M4
M5
M6
M7
)
Permissible dregs
AX0
MX0
SI
AX1
MX1
SE
AY0
MY0
SR0
AY1
MY1
SR1
AR
MR0
MR1
MR2
ADSP-218x DSP Instruction Set Reference
4-183
Multifunction Instructions
Description
Perform the designated arithmetic operation and data transfer. The write
operation moves the contents of the source to the specified memory location. The addressing mode when combining an arithmetic operation with
a memory write is register indirect with post-modify.
For linear (non-circular) indirect addressing, the L register corresponding
to the I register used must be set to zero. The contents of the source are
always right-justified in the destination register. The computation must be
unconditional. All ALU, MAC and Shifter operations are permitted
except Shift Immediate and ALU DIVS and DIVQ instructions.
The fundamental principle governing multifunction instructions is that
registers (and memory) are read at the beginning of the processor cycle
and written at the end of the cycle.
Status Generated (See Table 4-11 on page 4-30 for register notation)
All status bits are affected in the same way as for the single function versions of the selected arithmetic operation.
<ALU> operation
ASTAT
7
6
5
4
3
2
1
0
SS
MV
AQ
AS
AC
AV
AN
AZ
-
-
-
*
*
*
*
*
AZ
Set if result equals zero. Cleared otherwise.
AN
Set if result is negative. Cleared otherwise.
AV
Set if an overflow is generated. Cleared otherwise.
4-184
ADSP-218x DSP Instruction Set Reference
Instruction Set
AC
Set if a carry is generated. Cleared otherwise.
AS
Affected only when executing the Absolute Value operation (ABS). Set if the
source operand is negative.
<MAC> operation
ASTAT
7
6
5
4
3
2
1
0
SS
MV
AQ
AS
AC
AV
AN
AZ
-
*
-
-
-
-
-
-
Set if the accumulated product overflows the lower-order 32 bits of the MR
register. Cleared otherwise.
MV
<SHIFT> operation
ASTAT
7
6
5
4
3
2
1
0
SS
MV
AQ
AS
AC
AV
AN
AZ
*
-
-
-
-
-
-
-
Affected only when executing the EXP operation; set if the source operand is
negative. Cleared if the number is positive.
SS
Instruction Format
ALU/MAC operation with Data Memory Write, Instruction Type 4:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
1
1
G 1
Z
AMF
Yop
Xop
8
7
6
Dreg
5
4
3
I
ADSP-218x DSP Instruction Set Reference
2
1
0
M
4-185
Multifunction Instructions
ALU/MAC operation with Program Memory Write, Instruction Type 5:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
1
0
1
1
Z
AMF
Yop
8
Xop
7
6
5
4
Dreg
3
2
I
1
0
M
Shift operation with Data Memory Write, Instruction Type 12:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
1
0
0
1
G 1
SF
8
Xop
7
6
5
4
Dreg
3
2
I
1
0
M
Shift operation with Program Memory Write, Instruction Type 13:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
1
0
0
0
1
1
SF
8
Xop
7
6
5
4
Dreg
3
I
Z:
Result register
Dreg:
Destination register
SF:
Shifter operation
AMF:
ALU/MAC operation
Yop:
Y operand
Xop:
X operand
I:
Indirect address register
M
Modify register
G:
Data Address Generator; I and M registers must be from the same DAG, as
separated by the gray bar in the Syntax
description.
See Also
• “DREG Selection Codes” on page A-12
• “ALU/MAC Result Register Codes” on page A-22
• “Shifter Function Codes” on page A-18
• “DAG Selection Codes” on page A-15
4-186
ADSP-218x DSP Instruction Set Reference
2
1
M
0
Instruction Set
• “Index Register Selection Codes” on page A-15
• “Modify Register Selection Codes” on page A-16
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
• “AMF Function Codes” on page A-9
ADSP-218x DSP Instruction Set Reference
4-187
Multifunction Instructions
Data and Program Memory Read
Syntax
AX0
= DM(
I0
,
M0
)
AY0
= PM(
I4
,
M4
AX1
I1
M1
AY1
I5
M5
MX0
I2
M2
MY0
I6
M6
MX1
I3
M3
MY1
I7
M7
);
Description
Perform the designated memory reads, one from data memory and one
from program memory. Each read operation moves the contents of the
memory location to the destination register. For this double data fetch,
the destinations for data memory reads are the X registers in the ALU and
the MAC, and the destinations for program memory reads are the Y registers. The addressing mode for this memory read is register indirect with
post-modify. For linear (non-circular) indirect addressing, the L register
corresponding to the I register used must be set to zero. The contents of
the source are always right-justified in the destination register.
A multifunction instruction requires three items to be fetched from memory: the instruction itself and two data words. No extra cycle is needed to
execute the instruction as long as only one of the fetches is from external
memory.
If two off-chip accesses are required, however—the instruction fetch and
one data fetch, for example, or data fetches from both program and data
memory—then one overhead cycle occurs. In this case the program memory access occurs first, then the data memory access. If three off-chip
accesses are required—the instruction fetch as well as data fetches from
both program and data memory—then two overhead cycles occur.
Status Generated
4-188
ADSP-218x DSP Instruction Set Reference
Instruction Set
No status bits affected.
Instruction Format
ALU/MAC with Data and Program Memory Read, Instruction Type 1:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
1
0
PM
I
1
PD
DD
AMF
0
0
0
0
6
5
4
AMF specifies the ALU or MAC function. In this case, AMF
ignating a no-operation for the ALU or MAC function.
PD:
Program Destination register
AMF:
ALU/MAC operation
DD:
I:
3
DM
M
2
DM
I
1
0
DM
M
= 00000,
des-
Data Destination register
Indirect address register
Modify register
M:
See Also
• “Program Memory Destination Codes” on page A-16
• “Data Memory Destination Codes” on page A-12
• “Index Register Selection Codes” on page A-15
• “Modify Register Selection Codes” on page A-16
ADSP-218x DSP Instruction Set Reference
4-189
Multifunction Instructions
ALU/MAC With Data and Program Memory Read
Syntax
<ALU>
,
<MAC>
AX0
= DM(
I0
,
M0
),
AY0
=PM(
I4
,
M4
AX1
I1
M1
AY1
I5
M5
MX0
I2
M2
MY0
I6
M6
MX1
I3
M3
MY1
I7
M7
);
Description
This instruction combines an ALU or a MAC operation with a data memory read and a program memory read. The read operations move the
contents of the memory location to the destination register. For this double data fetch, the destinations for data memory reads are the X registers in
the ALU and the MAC, and the destinations for program memory reads
are the Y registers. The addressing mode is register indirect with
post-modify. For linear (non-circular) indirect addressing, the L register
corresponding to the I register used must be set to zero. The contents of
the source are always right-justified in the destination register after the
read.
A multifunction instruction requires three items to be fetched from memory: the instruction itself and two data words. No extra cycle is needed to
execute the instruction as long as only one of the fetches is from external
memory.
If two off-chip accesses are required such as the instruction fetch and one
data fetch or data fetches from both program and data memory, then one
overhead cycle occurs. In this case, the program memory access occurs
first, followed by the data memory access. If three off-chip accesses are
required such as the instruction fetch and data fetches from both program
and data memory, then two overhead cycles occur.
4-190
ADSP-218x DSP Instruction Set Reference
Instruction Set
The computation must be unconditional. All ALU and MAC operations
are permitted except the DIVS and DIVQ instructions. The results of the
computation must be written into the R register of the computational
unit: ALU results to AR, MAC results to MR.
The fundamental principle governing multifunction instructions is that
registers (and memory) are read at the beginning of the processor cycle
and written at the end of the cycle. The normal left-to-right order of
clauses (computation first, memory reads second) is intended to imply
this. In fact, you may code this instruction with the order of clauses
altered. The assembler produces a warning, but the results are identical at
the opcode level. If you turn off semantics checking in the assembler (–s
switch), the warning is not issued.
The same data register may be used as a source for the arithmetic operation and as a destination for the memory read. The register supplies the
value present at the beginning of the cycle and is written with the value
from memory at the end of the cycle.
For example,
(1) MR=MR+MX0*MY0(UU), MX0=DM(I0, M0), MY0=PM(I4,M4);
is a legal version of this multifunction instruction and is not flagged by the
assembler. Changing the order of clauses, as in
(2) MX0=DM(I0, M0), MY0=PM(I4,M4), MR=MR+MX0*MY0(UU);
results in an assembler warning, but assembles and executes exactly as the
first form of the instruction. Note that reading example (2) from left to
right may suggest that the data memory value is loaded into MX0 and MY0
and subsequently used in the computation, all in the same cycle. In fact,
this is not possible. The left-to-right logic of example (1) suggests the
operation of the instruction more closely. Regardless of the apparent logic
of reading the instruction from left to right, the read-first, write-second
operation of the processor determines what actually happens.
ADSP-218x DSP Instruction Set Reference
4-191
Multifunction Instructions
Status Generated
(See Table 4-11 on page 4-30 for register notation)
All status bits are affected in the same way as for the single operation version of the selected arithmetic operation.
<ALU> operation
ASTAT
7
6
5
4
3
2
1
0
SS
MV
AQ
AS
AC
AV
AN
AZ
-
-
-
*
*
*
*
*
AZ
Set if result equals zero. Cleared otherwise.
AN
Set if result is negative. Cleared otherwise.
AV
Set if an overflow is generated. Cleared otherwise.
AC
Set if a carry is generated. Cleared otherwise.
Affected only when executing the Absolute Value operation (ABS). Set if the
source operand is negative.
AS
<MAC> operation
ASTAT
MV
4-192
7
6
5
4
3
2
1
0
SS
MV
AQ
AS
AC
AV
AN
AZ
-
*
-
-
-
-
-
-
Set if the accumulated product overflows the lower-order 32 bits of the MR
register. Cleared otherwise.
ADSP-218x DSP Instruction Set Reference
Instruction Set
Instruction Format
ALU/MAC with Data and Program Memory Read, Instruction Type 1:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
1
1
PD
DD
AMF
Yop
Xop
8
7
6
5
4
3
PM
DM
DM
M
I
M
DD:
Data Destination register
AMF:
ALU/MAC operation
M:
Modify register
Xop:
X operand
I:
Indirect address register
0
PM
Program Destination register
Y operand
1
I
PD:
Yop:
2
See Also
• “Program Memory Destination Codes” on page A-16
• “Data Memory Destination Codes” on page A-12
• “Index Register Selection Codes” on page A-15
• “Modify Register Selection Codes” on page A-16
• “X Operand Codes” on page A-21
• “Y Operand Codes” on page A-21
• “AMF Function Codes” on page A-9
ADSP-218x DSP Instruction Set Reference
4-193
Multifunction Instructions
4-194
ADSP-218x DSP Instruction Set Reference
A INSTRUCTION CODING
This appendix gives a summary of the complete instruction set of the
ADSP-218x processors. This section is divided into two sections:
• “Opcode Definitions” on page A-2 — This section provides the
opcode bits listed by type number. Any instruction codes not
shown are reserved for future use.
• “Opcode Mnemonics” on page A-9 — This section is an alphabetic
listing that describes the values for each opcode mnemonic.
ADSP-218x DSP Instruction Set Reference
A-1
Opcode Definitions
Opcode Definitions
This section provides the definitions of opcode bits listed by type number.
Table A-1. Type 1: ALU / MAC With Data and Program Memory Read
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
1
1
PD
DD
AMF
Yop
8
Xop
7
6
PM
I
5
4
DM
M
3
2
DM
I
1
0
DM
M
Table A-2. Type 2: Data Memory Write (Immediate Data)
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
1
0
1
8
7
6
5
4
G Data
3
2
I
1
0
M
Table A-3. Type 3: Read / Write Data Memory (Immediate Address)
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
1
0
0
D RGP
8
7
6
5
4
ADDR
3
2
1
0
REG
Table A-4. Type 4: ALU / MAC With Data Memory Read / Write
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
1
1
G D Z
AMF
Yop
8
Xop
7
6
5
4
Dreg
3
2
I
1
0
M
Table A-5. Type 5: ALU / MAC With Program Memory Read / Write
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
1
0
1
D Z
AMF
Yop
8
Xop
7
6
5
4
Dreg
3
2
I
1
0
M
Table A-6. Type 6: Load Data Register Immediate
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
1
0
0
8
7
6
5
4
DATA
3
2
1
0
1
0
DREG
Table A-7. Type 7: Load Non-Data Register Immediate
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
A-2
0
1
1
RGP
8
DATA
ADSP-218x DSP Instruction Set Reference
7
6
5
4
3
2
REG
Instruction Coding
Table A-8. Type 8: ALU / MAC With Internal Data Register Move
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
1
Z
AMF
Yop
8
Xop
7
6
5
4
Dreg dest
3
2
1
0
Dreg source
Table A-9. Generate ALU Status (NONE = <ALU>)
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
1
0
AMF*
Yop
8
Xop
7
6
5
4
3
2
1
0
1
0
1
0
1
0
1
0
7
6
5
4
3
2
1
0
0
0
0
0
COND
1
0
* ALU codes only.
Table A-10. Type 9: Conditional ALU / MAC
xop * yop
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
Yop
8
Xop
xop * xop
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
0
0
8
Xop
7
6
5
4
3
0
0
0
1
COND
2
xop AND/OR/XOR constant
BO, CC, and YY specify the constant according the table shown at the end of this appendix.
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
YY
8
Xop
7
6
CC
5
4
BO
3
2
1
0
1
0
1
0
COND
PASS constant (constant ≠ 0,1, –1)
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
1
0
0
Z
AMF
YY
8
Xop
7
6
CC
5
4
BO
3
2
COND
Table A-11. Type 10: Conditional Jump (Immediate Address)
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
1
1
S
ADDR
8
7
6
5
4
3
2
COND
ADSP-218x DSP Instruction Set Reference
A-3
Opcode Definitions
Table A-12. Type 11: Do Until
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
1
0
1
8
7
6
5
4
Addr
3
2
1
0
1
0
TERM
Table A-13. Type 12: Shift With Data Memory Read / Write
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
1
0
0
1
G D SF
8
Xop
7
6
5
4
Dreg
3
2
I
M
Table A-14. Type 13: Shift With Program Memory Read / Write
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
1
0
0
0
1
D SF
8
Xop
7
6
5
4
Dreg
3
2
I
1
0
M
Table A-15. Type 14: Shift With Internal Data Register Move
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
1
0
0
0
0
0
SF
8
Xop
7
6
5
4
Dreg dest
3
2
1
0
Dreg source
Table A-16. Type 15: Shift Immediate
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
1
1
1
1
0
SF
8
Xop
7
6
5
4
3
2
1
0
2
1
0
<exp>
Table A-17. Type 16: Conditional Shift
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
A-4
0
0
0
1
1
1
0
0
SF
8
Xop
ADSP-218x DSP Instruction Set Reference
7
6
5
4
3
0
0
0
0
COND
Instruction Coding
Table A-18. Type 17: Internal Data Move
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
1
1
0
1
0
0
0
0
DST
RGP
8
SRC
RGP
7
6
5
4
3
DEST
REG
2
1
0
SOURCE
REG
Table A-19. Type 18: Mode Control
23 22 21 20 19 18 17 16 15 14 13
0
0
0
0
1
1
0
0
TI
12 11 10 9 8
MM
AS
OL
7
6
BR
5
SR
4
3
2
GM
1 0
0 0
Table A-20. Mode Control Codes
Mode
Meaning
Code
Meaning
SR
Secondary register bank
11
Enable mode
BR
Bit-reverse mode
10
Disable mode
OL
ALU overflow latch mode
01
No change
AS
AR register saturate mode
00
No change
MM
Alternate multiplier placement mode
GM
GO mode; enable means execute internal
code, if possible.
TI
Timer enable
ADSP-218x DSP Instruction Set Reference
A-5
Opcode Definitions
Table A-21. Type 19: Conditional Jump (Indirect Address)
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
0
0
0
I
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
0
0
0
0
0
0
1
0
1
1
0
0
0
0
0
0
6
5
4
3
2
0
S
COND
6
5
4
3
0
0
T
COND
1
0
1
0
Table A-22. Type 20: Conditional Return
0
0
0
1
0
1
0
0
0
0
0
0
0
0
2
Table A-23. Type 21: Modify Address Register
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3
0
0
0
0
1
0
0
1
0
0
0
0
0
0
2 1
0 0 0 0 0 G I
0
M
Table A-24. Type 22: Reserved
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
0
0
0
0
0
0
0
COND
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
0
0
0
0
7
6
5
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
2
1
0
2
1
0
0
0
0
0
4
3
2
1
0
0
0
0
0
0
Table A-25. Type 23: DIVQ
0
0
0
0
0
1
1
1
0
0
0
1
0
Xop
Table A-26. Type 24: DIVS
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
A-6
0
0
0
0
1
1
0
0
0
0
Yop
8
Xop
ADSP-218x DSP Instruction Set Reference
Instruction Coding
Table A-27. Type 25: Saturate MR
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
2
1
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
Table A-28. Type 26: Stack Control
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0 0 0 Iq
3
Pp Lp Cp Spp
Table A-29. Type 27: Call or Jump on Flag In
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
0
0
1
1
8
7
6
5
4
3
2
1
0
Address
Addr FIC
^ 12 LSBs
^ 2 MSBs
S
Table A-30. Type 28: Modify Flag Out
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
0
0
1
0
0
0
0
0
FO
8
FO
7
6
FO
5
4
FO
3
2
1
0
COND
^ FL2 ^ FL1 ^ FL0 ^ FLAG_OUT
Table A-31. Type 29: I/O Memory Space Read/Write
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
0
0
0
0
0
0
0
1
D ADDR
8
7
6
5
4
3
2
1
0
DREG
ADSP-218x DSP Instruction Set Reference
A-7
Opcode Definitions
Table A-32. Type 30: No Operation (NOP)
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0 0 0 0 0 0 0 0 0
Table A-33. Type 31: Idle
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
DV
0
0
0
0
0
1
0
1
0
0
0
0
0
Table A-34. Type 31: Idle (n) (Slow Idle)
A-8
0
0
0
0
0
1
0
1
0
0
0
0
0
0
ADSP-218x DSP Instruction Set Reference
Instruction Coding
Opcode Mnemonics
This section is an alphabetic listing that describes the values for each
opcode mnemonic.
AMF ALU / MAC Function Codes
0
0
0
0
0
No Operation
Table A-35. AMF Function Codes
Code
Function
Mnemonic
0
0
0
0
1
X*Y
(RND)
0
0
0
1
0
MR + X * Y
(RND)
0
0
0
1
1
MR – X * Y
(RND)
0
0
1
0
0
X*Y
(SS)
0
0
1
0
1
X*Y
(SU)
0
0
1
1
0
X*Y
(US)
0
0
1
1
1
X*Y
(UU)
0
1
0
0
0
MR + X * Y
(SS)
0
1
0
0
1
MR + X * Y
(SU)
0
1
0
1
0
MR + X * Y
(US)
0
1
0
1
1
MR + X * Y
(UU)
0
1
1
0
0
MR – X * Y
(SS)
0
1
1
0
1
MR – X * Y
(SU)
0
1
1
1
0
MR – X * Y
(US)
0
1
1
1
1
MR – X * Y
(UU)
Clear when y = 0
ADSP-218x DSP Instruction Set Reference
A-9
Opcode Mnemonics
Table A-36. ALU Function Codes
Code
Function
1
0
0
0
0
Y
Clear when y = 0
1
0
0
0
1
Y+1
PASS 1 when y = 0
1
0
0
1
0
X+Y+C
1
0
0
1
1
X+Y
1
0
1
0
0
NOT Y
1
0
1
0
1
–Y
1
0
1
1
0
X–Y+C–1
1
0
1
1
1
X–Y
1
1
0
0
0
Y–1
PASS –1 when y = 0
1
1
0
0
1
Y–X
– X when y = 0
1
1
0
1
0
Y–X+C–1
–X + C – 1 when y = 0
1
1
0
1
1
NOT X
1
1
1
0
0
X AND Y
1
1
1
0
1
X OR Y
1
1
1
1
0
X XOR Y
1
1
1
1
1
ABS X
X when y = 0
X + C – 1 when y = 0
BO
See “ALU/MAC Constant Codes” on page A-22.
CC
See “ALU/MAC Constant Codes” on page A-22.
A-10
ADSP-218x DSP Instruction Set Reference
Instruction Coding
COND Status Condition Codes
Table A-37. Status Condition Codes
Code
Description
Condition
0 0 0 0
Equal
EQ
0 0 0 1
Not equal
NE
0 0 1 0
Greater than
GT
0 0 1 1
Less than or equal
LE
Less than
LT
0 1 0 1
Greater than or equal
GE
0 1 1 0
ALU Overflow
AV
0 1 1 1
NOT ALU Overflow
NOT AV
1 0 0 0
ALU Carry
AC
1 0 0 1
Not ALU Carry
NOT AC
1 0 1 0
X input sign negative
NEG
1 0 1 1
X input sign positive
POS
1 1 0 0
MAC Overflow
MV
1 1 0 1
Not MAC Overflow
NOT MV
1 1 1 0
Not counter expired
NOT CE
1 1 1 1
Always true
0 1 0 0
CP Counter Stack Pop Codes
Table A-38. Counter Stack Pop Codes
Code
0
1
Description
No change
Pop
ADSP-218x DSP Instruction Set Reference
A-11
Opcode Mnemonics
D Direction Codes
Table A-39. Memory Access Direction Codes
Code
Description
0
Read
1
Write
DD Double Data Fetch Data Memory
Destination Codes
Table A-40. Data Memory Destination Codes
Code
Register
0 0
AX0
0 1
AX1
1 0
MX0
11
MX1
DREG Data Register Codes
Table A-41. DREG Selection Codes
Code
Register
0 0 0 0
AX0
0 0 0 1
AX1
0 0 1 0
MX0
0 0 1 1
MX1
0 1 0 0
AY0
0 1 0 1
AY1
A-12
ADSP-218x DSP Instruction Set Reference
Instruction Coding
Table A-41. DREG Selection Codes (Cont’d)
Code
Register
0 1 1 0
MY0
0 1 1 1
MY1
1 0 0 0
SI
1 0 0 1
SE
1 0 1 0
AR
1 0 1 1
MR0
1 1 0 0
MR1
1 1 0 1
MR2
1 1 1 0
SR0
1 1 1 1
SR1
ADSP-218x DSP Instruction Set Reference
A-13
Opcode Mnemonics
DV Divisor Codes for Slow Idle Instruction (IDLE (n))
Table A-42. Slow Idle Divisor Codes
Code
Divisor
0 0 0 0
Normal Idle instruction (Divisor=0)
0 0 0 1
Divisor=16
0 0 1 0
Divisor=32
0 1 0 0
Divisor=64
1 0 0 0
Divisor=128
FIC FI Condition Codes
Table A-43. FI Condition Codes
Code
1
0
Description
Condition
latched FI is 1
FLAG_IN
latched FI is 0
NOT FLAG_IN
FO Control Codes for Flag Output Pins
(FO, FL0, FL1, FL2)
Table A-44. FO Condition Codes
Code
Description
0 0
No change
0 1
Toggle
1 0
Reset
1 1
Set
A-14
ADSP-218x DSP Instruction Set Reference
Instruction Coding
G Data Address Generator Codes
Table A-45. DAG Selection Codes
Code
Address Generator
0
DAG1
1
DAG2
I Index Register Codes
Table A-46. Index Register Selection Codes
Code
G=0
G=1
0 0
I0
I4
0 1
I1
I5
1 0
I2
I6
1 1
I3
I7
LP Loop Stack Pop Codes
Table A-47. Loop Stack Pop Codes
Code
0
1
Description
No change
Pop
ADSP-218x DSP Instruction Set Reference
A-15
Opcode Mnemonics
M Modify Register Codes
Table A-48. Modify Register Selection Codes
Code
G=0
G=1
0 0
M0
M4
0 1
M1
M5
1 0
M2
M6
1 1
M3
M7
PD Dual Data Fetch Program Memory
Destination Codes
Table A-49. Program Memory Destination Codes
Code
Register
0 0
AY0
0 1
AY1
1 0
MY0
11
MY1
PP PC Stack Pop Codes
Table A-50. PC Stack Pop Codes
Code
A-16
Description
0
No change
1
Pop
ADSP-218x DSP Instruction Set Reference
Instruction Coding
REG Register Codes
The following table gives the register codes for register groups (RGP) 0, 1,
2 and 3. Codes that are not assigned (-) are reserved.
Table A-51. Register Selection Codes
Code
RGP = 00
(REG0)
RGP = 01
(REG1)
RGP = 10
(REG2)
RGP = 11
(REG3)
0 0 0 0
AX0
I0
I4
ASTAT
0 0 0 1
AX1
I1
I5
MSTAT
0 0 1 0
MX0
I2
I6
SSTAT (read only)
0 0 1 1
MX1
I3
I7
IMASK
0 1 0 0
AY0
M0
M4
ICNTL
0 1 0 1
AY1
M1
M5
CNTR
0 1 1 0
MY0
M2
M6
SB
0 1 1 1
MY1
M3
M7
PX
1 0 0 0
SI
L0
L4
RX0
1 0 0 1
SE
L1
L5
TX0
1 0 1 0
AR
L2
L6
RX1
1 0 1 1
MR0
L3
L7
TX1
1 1 0 0
MR1
–
-
IFC (write only)
1 1 0 1
MR2
–
–
OWRCNTR (write only)
1 1 1 0
SR0
PMOVLAY
–
–
1 1 1 1
SR1
DMOVLAY
–
–
ADSP-218x DSP Instruction Set Reference
A-17
Opcode Mnemonics
S Jump/Call Codes
Table A-52. Jump and Call Codes
Code
Function
0
Jump
1
Call
SF Shifter Function Codes
Table A-53. Shifter Function Codes
Code
Function
0 0 0 0
LSHIFT
(HI)
0 0 0 1
LSHIFT
(HI, OR)
0 0 1 0
LSHIFT
(LO)
0 0 1 1
LSHIFT
(LO, OR)
0 1 0 0
ASHIFT
(HI)
0 1 0 1
ASHIFT
(HI, OR)
0 1 1 0
ASHIFT
(LO)
0 1 1 1
ASHIFT
(LO, OR)
1 0 0 0
NORM
(HI)
1 0 0 1
NORM
(HI, OR)
1 0 1 0
NORM
(LO)
1 0 1 1
NORM
(LO, OR)
1 1 0 0
EXP
(HI)
1 1 0 1
EXP
(HIX)
1110
EXP
(LO)
1111
Derive Block Exponent
A-18
ADSP-218x DSP Instruction Set Reference
Instruction Coding
SPP Status Stack Push/Pop Codes
Table A-54. Status Stack Push and Pop Codes
Code
Description
0 0
No change
0 1
No change
1 0
Push
1 1
Pop
T Return Type Codes
Table A-55. Return Type Codes
Code
Return Type
0
Return from subroutine
1
Return from interrupt
ADSP-218x DSP Instruction Set Reference
A-19
Opcode Mnemonics
TERM Termination Codes for DO UNTIL
Table A-56. DO UNTIL Termination Codes
Code
Description
Condition
0 0 0 0
Not Equal
NE
0 0 0 1
Equal
EQ
0 0 1 0
Less than or equal
LE
0 0 1 1
Greater than
GT
0 1 0 0
Greater than or equal
GE
0 1 0 1
Less than
LT
0 1 1 0
NOT ALU Overflow
NOT AV
0 1 1 1
ALU Overflow
AV
1 0 0 0
Not ALU Carry
NOT AC
1 0 0 1
ALU Carry
AC
1 0 1 0
X input sign positive
POS
1 0 1 1
X input sign negative
NEG
1 1 0 0
Not MAC Overflow
NOT MV
1 1 0 1
MAC Overflow
MV
1 1 1 0
Counter expired
CE
1 1 1 1
Always
FOREVER
A-20
ADSP-218x DSP Instruction Set Reference
Instruction Coding
X X Operand Codes
Table A-57. X Operand Codes
Code
Register
0 0 0
X0
SI for shifter
0 0 1
X1
invalid for shifter
0 1 0
AR
0 1 1
MR0
1 0 0
MR1
1 0 1
MR2
1 1 0
SR0
1 1 1
SR1
Y Y Operand Codes
Table A-58. Y Operand Codes
Code
Register
0 0
Y0
0 1
Y1
1 0
F
1 1
zero
feedback register
YY
See “ALU/MAC Constant Codes” on page A-22.
ADSP-218x DSP Instruction Set Reference
A-21
Opcode Mnemonics
Z ALU/MAC Result Register Codes
Table A-59. ALU/MAC Result Register Codes
Code
Return Type
0
Result register
1
Feedback register
YY, CC, BO ALU / MAC Constant Codes (Type 9)
Table A-60. ALU/MAC Constant Codes
Constant (hex)
YY
CC
BO
Bit #
0001
00
00
01
bit 0
0002
00
01
01
bit 1
00
10
01
bit 2
0008
00
11
01
bit 3
0010
01
00
01
bit 4
0020
01
01
01
bit 5
0040
01
10
01
bit 6
0080
01
11
01
bit 7
0100
10
00
01
bit 8
0200
10
01
01
bit 9
0400
10
10
01
bit 10
0800
10
11
01
bit 11
1000
11
00
01
bit 12
2000
11
01
01
bit 13
4000
11
10
01
bit 14
8000
11
11
01
bit 15
0004
A-22
ADSP-218x DSP Instruction Set Reference
Instruction Coding
Table A-60. ALU/MAC Constant Codes (Cont’d)
Constant (hex)
YY
CC
BO
Bit #
FFFE
00
00
11
! bit 0
FFFD
00
01
11
! bit 1
FFFB
00
10
11
! bit 2
FFF7
00
11
11
! bit 3
FFEF
01
00
11
! bit 4
FFDF
01
01
11
! bit 5
FFBF
01
10
11
! bit 6
FF7F
01
11
11
! bit 7
FEFF
10
00
11
! bit 8
FDFF
10
01
11
! bit 9
FBFF
10
10
11
! bit 10
F7FF
10
11
11
! bit 11
EFFF
11
00
11
! bit 12
DFFF
11
01
11
! bit 13
BFFF
11
10
11
! bit 14
7FFF
11
11
11 !
! bit 15
ADSP-218x DSP Instruction Set Reference
A-23
Opcode Mnemonics
A-24
ADSP-218x DSP Instruction Set Reference
I
INDEX
A
C
absolute value (ABS) 4-15, 4-56, 4-179, 4-184,
4-189, 4-196
Add/Add with carry 4-32
ALU feedback (AF) register 2-7, 4-15, 4-20,
4-45–4-71
ALU input (AX and AY) registers 1-9, 2-1, 2-7,
4-9–4-14, 4-71, 4-117–4-135, 4-160–
4-194
ALU instructions 4-31
instruction syntax table 4-14
overview 4-14
summary 4-2, 4-31
ALU result (AR) register 2-7, 4-8, 4-9, 4-10,
4-14–4-66, 4-71–4-78, 4-82, 4-97,
4-117–4-163, 4-178, 4-183
ALU/MAC with data and program memory
read 4-194
arithmetic shift 4-97
arithmetic shift immediate 4-112
Arithmetic status (ASTAT) register 2-1, 2-6,
2-17, 4-46, 4-49, 4-64, 4-66, 4-71, 4-94,
4-104, 4-117, 4-128, 4-148, 4-156
arithmetic status (ASTAT) register 2-6
CALL instruction 2-16, 4-6, 4-22, 4-140, 4-142
cascaded biquad IIR filter example 3-7
clear 4-90
CLKOUT 2-8, 4-153
computation
units 2-7
with data register move 4-10
with memory read 4-9, 4-176
with memory write 4-10, 4-187
with register to register move 4-182
conditional
instructions 1-3
MR saturation 4-94
conventions 1-8
Counter (CNTR) register 2-5, 2-7, 2-15, 4-22,
4-117, 4-128, 4-138, 4-150
customer support 1-7
cycle conditions 4-27
B
bit manipulation
TSTBIT, SETBIT, CLRBIT, TGLBIT 4-45
bit-reverse subroutine 3-21
bitwise logic
AND, OR, XOR 4-42
block exponent adjust 4-110
D
DAG register
DAG1 2-2, 4-11, 4-25
DAG2 2-2, 4-11, 4-22
using with Toppstack instruction 4-160
data address generator 4-125, 4-131, 4-173
data address generators 2-2
data and program memory read 4-9, 4-192
data buffer
inplaceimag 3-14
inplacereal 3-14
inputimag 3-14
twid_imag 3-14
twid_real 3-14
ADSP-218x DSP Instruction Set Reference
I-1
INDEX
data memory
DMOVLAY register restoration example
2-18
Overlay (DMOVLAY) register 2-18
read (direct address) 4-122
read (indirect address) 4-124
write (direct address) 4-128
write (indirect address) 4-130
decrement 4-61
derive exponent 4-106
development
process 3-3
tools 1-4
disable (DIS) instruction 2-5, 2-6, 4-25, 4-26,
4-162
interrupt disable 4-165
divide algorithm
non-restoring 4-65
divide primitives 4-68
division
applications 4-69
divide primitives DIVS and DIVQ 4-63
exceptions 4-68
integer 4-67
negative divisor error 4-68
output formats 4-66
routine using DIVS & DIVQ 4-69
signed 4-66
theory of 4-65
unsigned 4-66
unsigned division error 4-69
DMOVLAY register update instruction 4-169
DO UNTIL instruction 2-5, 4-6, 4-150
DO UNTIL termination codes A-20
E
enable (ENA) instruction 2-5, 2-6, 4-25, 4-26,
4-162, 4-165
interrupt enable 4-165
examples
bit-reverse subroutine 3-21
DMOVLAY register restoration 2-18
IIR filter 3-7
I-2
examples
(continued)
PMOVLAY register restoration 2-18
Radix-2 decimation-in-time FFT 3-13
sine approximation 3-9
single-precision FIR transversal filter 3-5
single-precision matrix multiply 3-11
F
FFT 3-2
FI pin 4-22, 4-24, 4-142
FIR
filter 3-1
transversal filter example 3-5
FO pin 4-25, 4-144
G
generate ALU status 4-71
H
hardware overlays 2-16
I
IDLE instruction 2-13, 2-14, 4-6, 4-23, 4-153
IF condition codes table 4-23
IIR filter 3-7
increment 4-59
Index (I) register 2-1, 2-2, 2-4, 2-13, 4-6, 4-8,
4-25, 4-124–4-128, 4-131, 4-172, 4-177,
4-188, 4-192
indirect addressing 2-4
Indirect jumps 2-2
inplaceimag data buffer 3-14
inplacereal data buffer 3-14
inputimag data buffer 3-14
inputreal data buffer 3-14
instruction set
list of instructions 4-2
notation table 1-8
overview 4-5
syntax 4-28
ADSP-218x DSP Instruction Set Reference
INDEX
integer division 4-67
Interrupt control (ICNTL) register 2-5, 4-117,
4-128
interrupt enable and disable 4-165
Interrupt mask (IMASK) register 2-2, 2-5, 2-6,
2-17, 4-117, 4-128, 4-148, 4-156, 4-165
interrupts 2-5, 2-17
IO space read/write 4-135
J
JUMP instruction 2-16, 4-138, 4-153
JUMP or CALL on flag in pin 4-142
L
Length (L) register 2-2, 2-13, 2-17, 4-124,
4-126, 4-131, 4-134, 4-172, 4-177,
4-188, 4-192, 4-194
Load register immediate 4-119
logical
shift 4-100
shift immediate 4-114
loop counts 2-5
loop hardware 2-19
M
MAC clear 4-90
MAC instructions 4-73
conditions table 4-17
overview 4-16
summary 4-2, 4-73
MAC transfer MR 4-92
memory
access (off-chip) 4-27
memory interface 2-9
memory-mapped registers 2-2
MISC instructions 4-155
miscellaneous instructions
instructions table 4-25
overview 4-25
miscellaneous instructions
(continued)
summary 4-4, 4-155
mode
control 4-162
mode bits 2-6
Mode status (MSTAT) register 2-6, 2-7, 2-17,
4-117, 4-128, 4-148, 4-156, 4-162
bit table 4-162
Modify (M) register 2-2, 2-4, 2-13, 4-8, 4-25,
4-125, 4-127, 4-131, 4-172, 4-190
Modify address register 4-172
Modify flag out pin 4-144
Move instructions 4-116
overview 4-20
summary 4-3
syntax table 4-20
multifunction instructions
overview 4-7
summary 4-4, 4-175
valid combinations table 4-12
Multiplier feedback (MF) register 2-7, 4-90
Multiplier input (MX and MY) registers 2-2,
2-7, 4-7–4-22, 4-74–4-82, 4-117–4-135,
4-160, 4-176–4-195
Multiplier result (MR) register 2-7, 2-15, 4-106,
4-118, 4-119, 4-128, 4-130, 4-160,
4-163, 4-179, 4-183, 4-185, 4-189,
4-195, 4-196
multiply
4-74
with cumulative add 4-78
with cumulative subtract 4-82
N
negate 4-52
no operation 4-174
NONE 4-71, A-3
NOP 4-174
normalize 4-103
NOT 4-54
Notation 1-8
ADSP-218x DSP Instruction Set Reference
I-3
INDEX
O
opcode
definitions A-8
mnemonics A-9
opcode bits
Generate ALU status A-3
listed by type number A-2
Type 1
ALU / MAC with Data and Program
Memory Read A-2
Type 10
Conditional Jump (Immediate Address)
A-3
Type 11
Do Until A-4
Type 12
Shift with Data Memory Read / Write A-4
Type 13
Shift with Program Memory Read / Write
A-4
Type 14
Shift with Internal Data Register Move A-4
Type 15
Shift Immediate A-4
Type 16
Conditional Shift A-4
Type 17
Internal Data Move A-5
Type 18
Mode Control A-5
Type 19
Conditional Jump (Indirect Address) A-6
Type 2
Data Memory Write (Immediate Data)
A-2
Type 20
Conditional Return A-6
Type 21
Modify Address Register A-6
Type 22
Reserved A-6
Type 23
DIVQ A-6
I-4
opcode bits
(continued)
Type 24
DIVS A-6
Type 25
Saturate MR A-7
Type 26
Stack Control A-7
Type 27
Call or Jump on Flag In A-7
Type 28
Modify Flag Out A-7
Type 29
I/O Memory Space Read/Write A-7
Type 3
Read /Write Data Memory (Immediate
Address) A-2
Type 30
No Operation (NOP) A-8
Type 31
Idle A-8
Idle (n) (Slow Idle) A-8
Type 4
ALU / MAC with Data Memory Read /
Write A-2
Type 5
ALU / MAC with Program Memory Read
/ Write A-2
Type 6
Load Data Register Immediate A-2
Type 7
Load Non-Data Register Immediate A-2
Type 8
ALU / MAC with Internal Data Register
Move A-3
Type 9
Conditional ALU / MAC A-3
opcode values A-9
AMF ALU /MAC function codes A-9
condition codes A-11
counter stack pop codes A-11
DAG register codes A-15
data memory destination codes A-12
data register codes A-12
direction codes A-12
ADSP-218x DSP Instruction Set Reference
INDEX
opcode values
(continued)
divisor codes for slow idle instruction A-14
FI condition codes A-14
FO control codes for flag output pins A-14
index register codes A-15
Jump/Call codes A-18
loop stack pop codes A-15
modify register codes A-16
program memory destination codes A-16
Push/Pop codes A-19
REG register codes A-17
return type codes A-19
shifter function codes A-18
stack pop codes A-16
termination codes for DO UNTIL A-20
X X operand codes A-21
Y Y operand codes A-21
YY, CC, BO ALU / MAC constant codes
A-22
Z ALU/MAC result register codes A-22
overlays 2-16
OWRCNTR 2-5
program memory
(continued)
PMOVLAY register restoration example 2-18
read (indirect address) 4-126
write (indirect address) 4-133
program sequencer 2-4
programming model
overview 3-1
PROM splitter 3-5
PUSH STS instruction 2-7, 4-156, 4-157
P
S
PASS 4-16, 4-48, 4-71
PC stack 4-157
PMOVLAY register update instruction 4-166
POP CNTR instruction 2-7, 4-26, 4-156
POP LOOP instruction 2-6, 4-26, 4-156
POP STS instruction 2-7, 4-157
processor registers
reg and dreg table 4-21
program example 2-10
interrupt routine discussion 2-15
overview 2-1
setup routine discussion 2-13
program flow instructions 4-137
instructions table 4-23
summary 4-4
program memory
bus exchange (PX) register 2-8, 4-117, 4-126,
4-134
Overlay (PMOVLAY) registers 2-17, 2-19
Serial clock (SCLKDIV) register 2-8
serial port (SPORT) 4-28
SPORT autobuffering and DMA 4-28
SPORT enable bits 2-9
serial port (SPORT), SPORT0, SPORT1 2-8
Shifter bit (SB) register 2-7, 4-10, 4-18, 4-19,
4-110
Shifter exponent (SE) register 2-7, 4-18, 4-97,
4-98, 4-100, 4-160
Shifter input (SB) register 4-100, 4-103, 4-110,
4-122, 4-160
Shifter input (SI) register 2-7, 2-15, 4-18, 4-97
Shifter instructions 4-96
summary 4-3, 4-18
Shifter result (SR) register 2-7, 4-100, 4-103,
4-112, 4-114, 4-160
signed division 4-66
simulator 3-5
sine approximation example 3-9
R
Radix-2 decimation-in-time FFT example 3-13
Receive (RX) register 2-8, 2-15, 4-120
Receive frame (RFSDIV) register 2-8
register move 4-117
registers
table of registers 2-2
return from interrupt (RTI) instruction 2-7,
4-6, 4-23, 4-24, 4-148, 4-157
return from subroutine (RTS) instruction 2-16,
4-6, 4-23, 4-146, 4-157
ADSP-218x DSP Instruction Set Reference
I-5
INDEX
single-precision matrix multiply 3-11
squaring
instruction 4-86
operation 4-87
stack control 4-156
stacks 2-6
status
register notation 4-30
status bits 2-6
subroutine modules and comment information
table 3-2
subtract X-Y/subtract X-Y with borrow 4-35
subtract Y-X/subtract Y-X with borrow 4-39
System status (SSTAT) register 2-6, 4-117,
4-128, 4-158
T
Timer Registers
TCOUNT 2-8
TPERIOD 2-8
TSCALE 2-8
tools 1-4
TOPPCSTACK instruction 2-6, 4-157, 4-158
Transmit (TX) register 2-8, 2-15, 4-120
twid_imag data buffer 3-14
twid_real data buffer 3-14
U
unsigned division 4-66
W
wait states 4-27
I-6
ADSP-218x DSP Instruction Set Reference