armv7

Data types

• Byte ⇒ 8 bits
• Halfword ⇒ 16 bits
• Word ⇒ 32 bits

Expamples

Simple math

.global _start
_start:
	mov r0, #4
	mov r2, #2
 
	sub r1, r0, r2 ; r1 = r0 - r2

.global _start
_start:
	mov r0, #4
	mov r2, #2
 
	mul r1, r0, r2 ; r1 = r0 * r2

.global _start
_start:
	mov r0, #4
	mov r2, #2
 
	add r1, r0, r2 ; r1 = r0 + r2

LDR - pseudo-instruction loads a register

.global _start

.text
_start:
	ldr r0, =var1
	ldr r1, [r0]
	
.data
var1: .word 5
var2: .word 6

STR - load and Store with register offset

STR <source_register>, [<address_register>]

.global _start
 
.text
_start:
	ldr r0, =var1
	ldr r1, [r0]
	
	mov r2, #3
	ldr r3, =var2
	str r2, [r3] ; r3 == 3 
	
.data
var1: .word 5
var2: .word 6

Bitwise

AND

.global _start
_start:
	mov r0, #66
	and r1, r0 #38

OR

.global _start
_start:
	mov r0, #66
	or r1, r0 #38

EOR (XOR)

.global _start
_start:
	mov r0, #66
	eor r1, r0 #38

MVN (NOT)

.global _start
_start:
	mov r0, #66
	mvn r1, r0