Table Of ContentModern Assembly Language Programming
with the ARM Processor
This page intentionally left blank
Modern Assembly Language
Programming with the
ARM Processor
Larry D. Pyeatt
AMSTERDAM • BOSTON • HEIDELBERG • LONDON
NEW YORK • OXFORD • PARIS • SAN DIEGO
SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO
Newnes is an imprint of Elsevier
Newnes is an imprint of Elsevier
The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, UK
50 Hampshire Street, 5th Floor, Cambridge, MA 02139, USA
Copyright © 2016 Elsevier Inc. All rights reserved.
No part of this publication may be reproduced or transmitted in any form or by any means, electronic or
mechanical, including photocopying, recording, or any information storage and retrieval system, without
permission in writing from the publisher. Details on how to seek permission, further information about the
Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance
Center and the Copyright Licensing Agency, can be found at our website:www.elsevier.com/permissions.
This book and the individual contributions contained in it are protected under copyright by the Publisher (other
than as may be noted herein).
Notices
Knowledge and best practice in this field are constantly changing. As new research and experience broaden our
understanding, changes in research methods, professional practices, or medical treatment may become necessary.
Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using
any information, methods, compounds, or experiments described herein. In using such information or methods
they should be mindful of their own safety and the safety of others, including parties for whom they have a
professional responsibility.
To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability
for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or
from any use or operation of any methods, products, instructions, or ideas contained in the material herein.
Library of Congress Cataloging-in-Publication Data
A catalog record for this book is available from the Library of Congress
British Library Cataloging-in-Publication Data
A catalogue record for this book is available from the British Library
ISBN: 978-0-12-803698-3
For information on all Newnes publications
visit our website at https://www.elsevier.com/
Publisher: Joe Hayton
Acquisition Editor: Tim Pitts
Editorial Project Manager: Charlotte Kent
Production Project Manager: Julie-Ann Stansfield
Designer: Mark Rogers
Typeset by SPi Global, India
Contents
List of Tables....................................................................................xiii
List of Figures....................................................................................xv
List of Listings ................................................................................. xvii
Preface........................................................................................... xxi
Companion Website........................................................................... xxv
Acknowledgments ............................................................................ xxvii
PART I
ASSEMBLY AS A LANGUAGE
1
Chapter 1: Introduction .........................................................................3
1.1 Reasons to Learn Assembly .................................................................... 4
1.2 The ARM Processor .............................................................................. 8
1.3 Computer Data..................................................................................... 9
1.3.1 Representing Natural Numbers............................................................. 9
1.3.2 Base Conversion ..............................................................................11
1.3.3 Representing Integers........................................................................15
1.3.4 Representing Characters ....................................................................20
1.4 Memory Layout of an Executing Program ................................................ 28
1.5 Chapter Summary ............................................................................... 31
Chapter 2: GNU Assembly Syntax ........................................................... 35
2.1 Structure of an Assembly Program ......................................................... 36
2.1.1 Labels............................................................................................37
2.1.2 Comments ......................................................................................37
2.1.3 Directives .......................................................................................37
2.1.4 Assembly Instructions .......................................................................38
2.2 What the Assembler Does..................................................................... 38
2.3 GNU Assembly Directives.................................................................... 40
2.3.1 Selecting the Current Section ..............................................................40
2.3.2 Allocating Space for Variables and Constants .........................................41
2.3.3 Filling and Aligning..........................................................................43
2.3.4 Setting and Manipulating Symbols.......................................................45
v
vi
Contents
2.3.5 Conditional Assembly .......................................................................46
2.3.6 Including Other Source Files ..............................................................47
2.3.7 Macros...........................................................................................48
2.4 Chapter Summary ............................................................................... 50
Chapter 3: Load/Store and Branch Instructions............................................ 53
3.1 CPU Components and Data Paths........................................................... 54
3.2 ARM User Registers ........................................................................... 55
3.3 Instruction Components ....................................................................... 58
3.3.1 Setting and Using Condition Flags .......................................................58
3.3.2 Immediate Values.............................................................................59
3.4 Load/Store Instructions ........................................................................ 60
3.4.1 Addressing Modes............................................................................61
3.4.2 Load/Store Single Register .................................................................64
3.4.3 Load/Store Multiple Registers.............................................................65
3.4.4 Swap .............................................................................................68
3.4.5 Exclusive Load/Store ........................................................................69
3.5 Branch Instructions ............................................................................. 70
3.5.1 Branch ...........................................................................................70
3.5.2 Branch and Link ..............................................................................71
3.6 Pseudo-Instructions............................................................................. 73
3.6.1 Load Immediate...............................................................................73
3.6.2 Load Address ..................................................................................75
3.7 Chapter Summary ............................................................................... 76
Chapter 4: Data Processing and Other Instructions ....................................... 79
4.1 Data Processing Instructions ................................................................. 79
4.1.1 Operand2 .......................................................................................80
4.1.2 Comparison Operations .....................................................................81
4.1.3 Arithmetic Operations .......................................................................83
4.1.4 Logical Operations ...........................................................................85
4.1.5 Data Movement Operations ................................................................86
4.1.6 Multiply Operations with 32-bit Results ................................................87
4.1.7 Multiply Operations with 64-bit Results ................................................88
4.1.8 Division Operations ..........................................................................89
4.2 Special Instructions ............................................................................. 90
4.2.1 Count Leading Zeros.........................................................................90
4.2.2 Accessing the CPSR and SPSR ...........................................................91
4.2.3 Software Interrupt ............................................................................91
4.2.4 Thumb Mode ..................................................................................92
4.3 Pseudo-Instructions............................................................................. 93
4.3.1 No Operation ..................................................................................93
4.3.2 Shifts.............................................................................................94
4.4 Alphabetized List of ARM Instructions ................................................... 95
4.5 Chapter Summary ............................................................................... 96
Contents
vii
Chapter 5: Structured Programming......................................................... 99
5.1 Sequencing.......................................................................................100
5.2 Selection..........................................................................................101
5.2.1 Using Conditional Execution ............................................................ 101
5.2.2 Using Branch Instructions ................................................................ 102
5.2.3 Complex Selection ......................................................................... 103
5.3 Iteration...........................................................................................104
5.3.1 Pre-Test Loop................................................................................ 105
5.3.2 Post-Test Loop .............................................................................. 106
5.3.3 For Loop ...................................................................................... 106
5.4 Subroutines ......................................................................................108
5.4.1 Advantages of Subroutines ............................................................... 109
5.4.2 Disadvantages of Subroutines ........................................................... 110
5.4.3 Standard C Library Functions ........................................................... 110
5.4.4 Passing Arguments ......................................................................... 110
5.4.5 Calling Subroutines ........................................................................ 113
5.4.6 Writing Subroutines........................................................................ 117
5.4.7 Automatic Variables........................................................................ 118
5.4.8 Recursive Functions........................................................................ 119
5.5 Aggregate Data Types.........................................................................123
5.5.1 Arrays ......................................................................................... 124
5.5.2 Structured Data.............................................................................. 124
5.5.3 Arrays of Structured Data ................................................................ 126
5.6 Chapter Summary ..............................................................................131
Chapter 6: Abstract Data Types ........................................................... 137
6.1 ADTs in Assembly Language...............................................................138
6.2 Word Frequency Counts ......................................................................139
6.2.1 Sorting by Word Frequency .............................................................. 147
6.2.2 Better Performance......................................................................... 150
6.3 Ethics Case Study: Therac-25...............................................................161
6.3.1 History of the Therac-25 .................................................................. 162
6.3.2 Overview of Design Flaws ............................................................... 163
6.4 Chapter Summary ..............................................................................165
PART II
PERFORMANCE MATHEMATICS
169
Chapter 7: Integer Mathematics ........................................................... 171
7.1 Subtraction by Addition ......................................................................172
7.2 Binary Multiplication .........................................................................172
7.2.1 Multiplication by a Power of Two ...................................................... 173
7.2.2 Multiplication of Two Variables......................................................... 173
7.2.3 Multiplication of a Variable by a Constant ........................................... 177
viii
Contents
7.2.4 Signed Multiplication...................................................................... 178
7.2.5 Multiplying Large Numbers ............................................................. 179
7.3 Binary Division .................................................................................181
7.3.1 Division by a Power of Two.............................................................. 181
7.3.2 Division by a Variable ..................................................................... 182
7.3.3 Division by a Constant .................................................................... 190
7.3.4 Dividing Large Numbers.................................................................. 194
7.4 Big Integer ADT................................................................................195
7.5 Chapter Summary ..............................................................................216
Chapter 8: Non-Integral Mathematics..................................................... 219
8.1 Base Conversion of Fractional Numbers .................................................220
8.1.1 Arbitrary Base to Decimal................................................................ 220
8.1.2 Decimal to Arbitrary Base................................................................ 220
8.2 Fractions and Bases............................................................................223
8.3 Fixed-Point Numbers..........................................................................226
8.3.1 Interpreting Fixed-Point Numbers...................................................... 226
8.3.2 Q Notation.................................................................................... 230
8.3.3 Properties of Fixed-Point Numbers .................................................... 230
8.4 Fixed-Point Operations .......................................................................231
8.4.1 Fixed-Point Addition and Subtraction ................................................. 231
8.4.2 Fixed Point Multiplication................................................................ 232
8.4.3 Fixed Point Division ....................................................................... 234
8.4.4 Division by a Constant .................................................................... 236
8.5 Floating Point Numbers ......................................................................242
8.5.1 IEEE 754 Half-Precision.................................................................. 243
8.5.2 IEEE 754 Single-Precision ............................................................... 245
8.5.3 IEEE 754 Double-Precision.............................................................. 245
8.5.4 IEEE 754 Quad-Precision ................................................................ 246
8.6 Floating Point Operations ....................................................................246
8.6.1 Floating Point Addition and Subtraction.............................................. 246
8.6.2 Floating Point Multiplication and Division........................................... 247
8.7 Computing Sine and Cosine .................................................................247
8.7.1 Formats for the Powers of x .............................................................. 248
8.7.2 Formats and Constants for the Factorial Terms...................................... 249
8.7.3 Putting it All Together..................................................................... 251
8.7.4 Performance Comparison................................................................. 259
8.8 Ethics Case Study: Patriot Missile Failure ...............................................261
8.9 Chapter Summary ..............................................................................263
Chapter 9: The ARM Vector Floating Point Coprocessor ............................... 265
9.1 Vector Floating Point Overview ............................................................266
9.2 Floating Point Status and Control Register ..............................................268
9.2.1 Performance Versus Compliance ....................................................... 271
9.2.2 Vector Mode ................................................................................. 272
9.3 Register Usage Rules..........................................................................273
Contents
ix
9.4
Load/Store Instructions .....................................................................274
9.4.1
Load/Store Single Register .......................................................... 274
9.4.2
Load/Store Multiple Registers...................................................... 275
9.5
Data Processing Instructions...............................................................277
9.5.1
Copy, Absolute Value, Negate, and Square Root............................... 277
9.5.2
Add, Subtract, Multiply, and Divide .............................................. 278
9.5.3
Compare ................................................................................. 279
9.6
Data Movement Instructions...............................................................279
9.6.1
Moving Between Two VFP Registers ............................................ 279
9.6.2
Moving Between VFP Register and One Integer Register................... 280
9.6.3
Moving Between VFP Register and Two Integer Registers ................. 281
9.6.4
Move Between ARM Register and VFP System Register ................... 282
9.7
Data Conversion Instructions ..............................................................282
9.7.1
Convert Between Floating Point and Integer.................................... 282
9.7.2
Convert Between Fixed Point and Single Precision ........................... 284
9.8
Floating Point Sine Function ..............................................................285
9.8.1
Sine Function Using Scalar Mode ................................................. 285
9.8.2
Sine Function Using Vector Mode................................................. 287
9.8.3
Performance Comparison............................................................ 291
9.9
Alphabetized List of VFP Instructions ..................................................292
9.10 Chapter Summary ............................................................................293
Chapter 10: The ARM NEON Extensions ................................................ 297
10.1 NEON Intrinsics ..............................................................................299
10.2 Instruction Syntax ............................................................................299
10.3 Load and Store Instructions ................................................................302
10.3.1
Load or Store Single Structure Using One Lane ............................... 303
10.3.2
Load Copies of a Structure to All Lanes ......................................... 305
10.3.3
Load or Store Multiple Structures ................................................. 307
10.4 Data Movement Instructions...............................................................309
10.4.1
Moving Between NEON Scalar and Integer Register......................... 309
10.4.2
Move Immediate Data ................................................................ 310
10.4.3
Change Size of Elements in a Vector ............................................. 311
10.4.4
Duplicate Scalar........................................................................ 312
10.4.5
Extract Elements ....................................................................... 313
10.4.6
Reverse Elements ...................................................................... 314
10.4.7
Swap Vectors ........................................................................... 315
10.4.8
Transpose Matrix ...................................................................... 316
10.4.9
Table Lookup ........................................................................... 317
10.4.10 Zip or Unzip Vectors.................................................................. 319
10.5 Data Conversion ..............................................................................321
10.5.1
Convert Between Fixed Point and Single-Precision........................... 321
10.5.2
Convert Between Half-Precision and Single-Precision....................... 322
10.6 Comparison Operations .....................................................................322
10.6.1
Vector Compare ........................................................................ 323
x
Contents
10.6.2
Vector Absolute Compare.......................................................... 324
10.6.3
Vector Test Bits....................................................................... 325
10.7
Bitwise Logical Operations...............................................................326
10.7.1
Bitwise Logical Operations........................................................ 326
10.7.2
Bitwise Logical Operations with Immediate Data ........................... 327
10.7.3
Bitwise Insertion and Selection................................................... 328
10.8
Shift Instructions ............................................................................329
10.8.1
Shift Left by Immediate ............................................................ 329
10.8.2
Shift Left or Right by Variable.................................................... 330
10.8.3
Shift Right by Immediate .......................................................... 331
10.8.4
Saturating Shift Right by Immediate ............................................ 332
10.8.5
Shift and Insert ....................................................................... 333
10.9
Arithmetic Instructions ....................................................................335
10.9.1
Vector Add and Subtract ........................................................... 335
10.9.2
Vector Add and Subtract with Narrowing...................................... 336
10.9.3
Add or Subtract and Divide by Two ............................................. 337
10.9.4
Add Elements Pairwise ............................................................. 338
10.9.5
Absolute Difference ................................................................. 339
10.9.6
Absolute Value and Negate ........................................................ 340
10.9.7
Get Maximum or Minimum Elements .......................................... 341
10.9.8
Count Bits.............................................................................. 342
10.10 Multiplication and Division ..............................................................343
10.10.1 Multiply ................................................................................ 343
10.10.2 Multiply by Scalar ................................................................... 345
10.10.3 Fused Multiply Accumulate ....................................................... 346
10.10.4 Saturating Multiply and Double (Low) ......................................... 347
10.10.5 Saturating Multiply and Double (High) ........................................ 348
10.10.6 Estimate Reciprocals ................................................................ 348
10.10.7 Reciprocal Step....................................................................... 349
10.11 Pseudo-Instructions.........................................................................351
10.11.1 Load Constant ........................................................................ 351
10.11.2 Bitwise Logical Operations with Immediate Data ........................... 352
10.11.3 Vector Absolute Compare.......................................................... 353
10.12 Performance Mathematics: A Final Look at Sine ...................................354
10.12.1 Single Precision ...................................................................... 354
10.12.2 Double Precision ..................................................................... 355
10.12.3 Performance Comparison .......................................................... 357
10.13 Alphabetized List of NEON Instructions..............................................358
10.14 Chapter Summary...........................................................................361
PART III
ACCESSING DEVICES
363
Chapter 11: Devices ......................................................................... 365
11.1
Accessing Devices Directly Under Linux.............................................365
Contents
xi
11.2 General Purpose Digital Input/Output ...................................................376
11.2.1 Raspberry Pi GPIO...................................................................... 378
11.2.2 pcDuino GPIO ........................................................................... 382
11.3 Chapter Summary ............................................................................392
Chapter 12: Pulse Modulation.............................................................. 395
12.1 Pulse Density Modulation ..................................................................396
12.2 Pulse Width Modulation ....................................................................397
12.3 Raspberry Pi PWM Device.................................................................398
12.4 pcDuino PWM Device ......................................................................400
12.5 Chapter Summary ............................................................................403
Chapter 13: Common System Devices ..................................................... 405
13.1 Clock Management Device ................................................................405
13.1.1 Raspberry Pi Clock Manager ......................................................... 406
13.1.2 pcDuino Clock Control Unit.......................................................... 409
13.2 Serial Communications .....................................................................409
13.2.1 UART ...................................................................................... 410
13.2.2 Raspberry Pi UART0 ................................................................... 413
13.2.3 Basic Programming for the Raspberry Pi UART ................................ 418
13.2.4 pcDuino UART .......................................................................... 422
13.3 Chapter Summary ............................................................................429
Chapter 14: Running Without an Operating System .................................... 431
14.1 ARM CPU Modes............................................................................432
14.2 Exception Processing ........................................................................434
14.2.1 Handling Exceptions ................................................................... 438
14.3 The Boot Process .............................................................................442
14.4 Writing a Bare-Metal Program ............................................................442
14.4.1 Startup Code.............................................................................. 443
14.4.2 Main Program ............................................................................ 445
14.4.3 The Linker Script........................................................................ 447
14.4.4 Putting it All Together.................................................................. 449
14.5 Using an Interrupt ............................................................................449
14.5.1 Startup Code.............................................................................. 449
14.5.2 Interrupt Controllers .................................................................... 449
14.5.3 Timers...................................................................................... 458
14.5.4 Exception Handling..................................................................... 461
14.5.5 Building the Interrupt-Driven Program ............................................ 461
14.6 ARM Processor Profiles ....................................................................461
14.7 Chapter Summary ............................................................................464
Index
467
This page intentionally left blank
List of Tables
Table 1.1
Values represented by two bits
9
Table 1.2
The first 21 integers (starting with 0) in various bases
10
Table 1.3
The ASCII control characters
21
Table 1.4
The ASCII printable characters
22
Table 1.5
Binary equivalents for each character in “Hello World”
23
Table 1.6
Binary, hexadecimal, and decimal equivalents for each character in “Hello
World”
24
Table 1.7
Interpreting a hexadecimal string as ASCII
24
Table 1.8
Variations of the ISO 8859 standard
25
Table 1.9
UTF-8 encoding of the ISO/IEC 10646 code points
27
Table 3.1
Flag bits in the CPSR register
58
Table 3.2
ARM condition modifiers
59
Table 3.3
Legal and illegal values for #<immediate|symbol>
60
Table 3.4
ARM addressing modes
61
Table 3.5
ARM shift and rotate operations
61
Table 4.1
Shift and rotate operations in Operand2
80
Table 4.2
Formats for Operand2
81
Table 8.1
Format for IEEE 754 half-precision
244
Table 8.2
Result formats for each term
252
Table 8.3
Shifts required for each term
252
Table 8.4
Performance of sine function with various implementations
259
Table 9.1
Condition code meanings for ARM and VFP
271
Table 9.2
Performance of sine function with various implementations
292
Table 10.1
Parameter combinations for loading and storing a single structure
304
Table 10.2
Parameter combinations for loading multiple structures
306
Table 10.3
Parameter combinations for loading copies of a structure
308
Table 10.4
Performance of sine function with various implementations
357
Table 11.1
Raspberry Pi GPIO register map
379
Table 11.2
GPIO pin function select bits
380
Table 11.3
GPPUD control codes
381
Table 11.4
Raspberry Pi expansion header useful alternate functions
385
Table 11.5
Number of pins available on each of the AllWinner A10/A20 PIO ports
385
Table 11.6
Registers in the AllWinner GPIO device
386
Table 11.7
Allwinner A10/A20 GPIO pin function select bits
388
Table 11.8
Pull-up and pull-down resistor control codes
389
Table 11.9
pcDuino GPIO pins and function select code assignments.
392
xiii
xiv
List of Tables
Table 12.1
Raspberry Pi PWM register map
398
Table 12.2
Raspberry Pi PWM control register bits
399
Table 12.3
Prescaler bits in the pcDuino PWM device
401
Table 12.4
pcDuino PWM register map
401
Table 12.5
pcDuino PWM control register bits
402
Table 13.1
Clock sources available for the clocks provided by the clock manager
407
Table 13.2
Some registers in the clock manager device
407
Table 13.3
Bit fields in the clock manager control registers
408
Table 13.4
Bit fields in the clock manager divisor registers
408
Table 13.5
Clock signals in the AllWinner A10/A20 SOC
409
Table 13.6
Raspberry Pi UART0 register map
413
Table 13.7
Raspberry Pi UART data register
414
Table 13.8
Raspberry Pi UART receive status register/error clear register
415
Table 13.9
Raspberry Pi UART flags register bits
415
Table 13.10
Raspberry Pi UART integer baud rate divisor
416
Table 13.11
Raspberry Pi UART fractional baud rate divisor
416
Table 13.12
Raspberry Pi UART line control register bits
416
Table 13.13
Raspberry Pi UART control register bits
417
Table 13.14
pcDuino UART addresses
422
Table 13.15
pcDuino UART register offsets
423
Table 13.16
pcDuno UART receive buffer register
424
Table 13.17
pcDuno UART transmit holding register
424
Table 13.18
pcDuno UART divisor latch low register
424
Table 13.19
pcDuno UART divisor latch high register
425
Table 13.20
pcDuno UART FIFO control register
425
Table 13.21
pcDuno UART line control register
426
Table 13.22
pcDuno UART line status register
427
Table 13.23
pcDuno UART status register
427
Table 13.24
pcDuno UART transmit FIFO level register
428
Table 13.25
pcDuno UART receive FIFO level register
428
Table 13.26
pcDuno UART transmit halt register
428
Table 14.1
The ARM user and system registers
433
Table 14.2
Mode bits in the PSR
434
Table 14.3
ARM vector table
435
