ARM Assembly Language - GBV

ARM Assembly Language Fundamentals and Techniques

William Hohl ARM Incorporated, Austin, Texas

CRC Press Taylor & Francis Group Boca Raton London

NewYork

CRC Press is an imprint of the Taylor & Francis Group, an informa business

Contents Preface Acknowledgments Software Notice Author Chapter 1

An Overview of Computing Systems 1.1 1.2

1.3 1.4 1.5

1.6 1.7 1.8 Chapter 2

Introduction History of RISC 1.2.1 ARM Begins 1.2.2 The Creation of ARM Ltd 1.2.3 ARM Today The Computing Device Number Systems Representations of Numbers and Characters 1.5.1 Integer Representations 1.5.2 Floating-Point Representations 1.5.3 Character Representations Translating Bits to Commands The Tools Exercises

1 1 2 5 6 9 10 11 14 15 18 20 21 22 25

The ARM7TDMI Programmer's Model

29

2.1 2.2 2.3 2.4 2.5

29 29 30 31 33 34 34 34 35

2.6 2.7 Chapter 3

xiii xvii xix xxi

Introduction Data Types Processor Modes Registers Program Status Registers 2.5.1 The Control Bits 2.5.2 The Mode Bits The Vector Table Exercises

First Programs

37

3.1 3.2

37 38 39 40 41 43

3.3 3.4

Introduction Program 1: Shifting Data 3.2.1 Running the Code 3.2.2 Examining Register and Memory Contents Program 2: Factorial Calculation Program 3: Swapping Register Contents

vii

Contents

VIII

3.5 3.6 Chapter 4

Programming Guidelines Exercises

44 45

Assembler Rules and Directives

47

4.1 4.2 4.3 4.4

47 47 50 51 51 52

4.5 4.6

4.7 Chapter 5

53 54 54 55 56 56 57 57 59 59 61 61

Loads, Stores, and Addressing

63

5.1 5.2 5.3 5.4

63 63 66 69 69 71 72 74 75 76

5.5

5.6 Chapter 6

Introduction Structure of Assembly Language Modules Predefined Register Names Frequently Used Directives 4.4.1 AREA—Define a Block of Data or Code 4.4.2 RN—Register Name Definition 4.4.3 EQU—Equate a Symbol to a Numeric Constant 4.4.4 ENTRY—Declare an Entry Point 4.4.5 DCB, DCW, and DCD—Allocate Memory and Specify Contents 4.4.6 ALIGN—Align Data or Code to Appropriate Boundaries 4.4.7 SPACE—Reserve a Block of Memory 4.4.8 LTORG—Assign Literal Pool Origins 4.4.9 END—End of a Source File Macros Miscellaneous Assembler Features 4.6.1 Assembler Operators 4.6.2 Literals Exercises

Introduction Memory Loads and Stores—The Instructions Operand Addressing 5.4.1 Pre-Indexed Addressing 5.4.2 Post-Indexed Addressing Endianness 5.5.1 Changing Endianness 5.5.2 Defining Memory Areas Exercises

Constants and Literal Pools

79

6.1 6.2 6.3 6.4 6.5

79 79 82 86 91

Introduction The ARM Rotation Scheme Loading Constants into Registers Loading Addresses into Registers Exercises

Contents Chapter 7

ix Logic and Arithmetic 7.1 7.2

7.3 7.4

7.5 7.6 Chapter 8

93 93 93 94 95 95 95 97 97 98 104 106 107 108 Ill 115

Loops and Branches

119

8.1 8.2 8.3

119 120 123 124 124 128 128 128 131 132

8.4 8.5 8.6 8.7 Chapter 9

Introduction Flags and Their Use 7.2.1 The N Flag 7.2.2 The V Flag 7.2.3 The Z Flag 7.2.4 The С Flag Comparison Instructions Data Processing Operations 7.4.1 Boolean Operations 7.4.2 Shifts and Rotates 7.4.3 Addition/Subtraction 7.4.4 Multiplication 7.4.5 Multiplication by a Constant 7.4.6 Division Fractional Notation Exercises

93

Introduction Branching Looping 8.3.1 While Loops 8.3.2 For Loops 8.3.3 Do ... While Loops More on Flags Conditional Execution Straight-Line Coding Exercises

Tables 9.1 9.2 9.3 9.4 9.5

135 Introduction Lookup Tables Jump Tables Binary Searches Exercises

135 135 139 140 143

Chapter 10 Subroutines and Stacks

147

10.1 Introduction 10.2 The Stack 10.2.1 LDM/STM Instructions 10.2.2 Full/Empty Ascending/Descending Stacks 10.3 Subroutines

147 147 148 150 152

x

Contents

10.4 Passing Parameters to Subroutines 10.4.1 Passing Parameters in Registers 10.4.2 Passing Parameters by Reference 10.4.3 Passing Parameters on the Stack 10.5 The ARM APCS 10.6 Exercises Chapter 11 Exception Handling 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8

Introduction Interrupts Error Conditions Processor Exception Sequence The Vector Table Exception Handlers Exception Priorities Procedures for Handling Exceptions 11.8.1 Reset Exceptions 11.8.2 Undefined Instructions 11.8.3 Interrupts 11.8.4 Aborts 11.8.5 SWIs 11.9 Exercises

Chapter 12 Memory-Mapped Peripherals 12.1 Introduction 12.2 The LPC2104 12.2.1 The UART 12.2.2 The Memory Map 12.2.3 Configuring the UART 12.2.4 Writing the Data to the UART 12.2.5 Putting the Code Together 12.2.6 Running the Code 12.3 TheLPC2132 12.3.1 The D/A Converter 12.3.2 The Memory Map 12.3.3 Configuring the D/A Converter 12.3.4 Generating a Sine Wave 12.3.5 Putting the Code Together 12.3.6 Running the Code 12.4 Exercises Chapter 13 THUMB 13.1 Introduction 13.2 THUMB Instructions

153 154 156 158 160 161 165 165 165 166 167 169 171 172 173 173 174 178 187 190 191 193 193 194 195 195 197 199 199 201 202 203 204 204 205 206 208 209 211 211 212

Contents

xi

13.3 Differences Between ARM and THUMB 13.4 THUMB Implementation and Use 13.4.1 Processor Hardware 13.4.2 Switching Between ARM and THUMB States 13.5 How to Compile for THUMB 13.6 Exercises Chapter 14 Mixing С and Assembly

213 215 215 216 218 220 223

14.1 Introduction 223 14.2 Inline Assembler 223 14.2.1 Inline Assembly Syntax 226 14.2.2 Restrictions on Inline Assembly Operations 228 14.3 Embedded Assembler 228 14.3.1 Embedded Assembly Syntax 230 14.3.2 Restrictions on Embedded Assembly Operations.... 231 14.4 Calling Between С and Assembly 231 14.5 Exercises 233 Appendix A The ARM V4T Instruction Set

235

Appendix В Running Keil Tools B.l Introduction B.2 Creating a Project and Selecting a Device B.3 Creating Application Code B.4 Building the Project and Running Code

333 333 333 335 336

Appendix С ASCII Character Codes

339

Glossary

341

References

343

Index

345