I want to load 1 32 bit hexadecimal directly into a register using arm assembly.
mov r1,#0x6c617669
This cannot be used because from this instruction we can only load 8 bit values. So I have load the 32 bit value directly from the memory. So how can I store the 32 bit value in memory and load it directly to a register using arm assembly?
I tried this code.
.global main
main:
sub sp,sp,#4
str lr,[sp,#0]
sub sp,sp,#4
str r0,x
add sp,sp,#4
ldr lr,[sp,#0]
add sp,sp,#4
mov pc,lr
.data
x: .word 0x6c617669
But gives the following error.
test1.s: Assembler messages:
test1.s:45: Error: internal_relocation (type: OFFSET_IMM) not fixed up
You have two basic choices. You can load it or build up the register 8 non-zero bits at a time
mov r0,#0x12000000 @ construct from 8-bit rotated immediates
orr r0,r0,#0x00340000
orr r0,r0,#0x00005600
orr r0,r0,#0x00000078
...
ldr r1,=0x12345678 @ let the assembler figure out how
...
ldr r3,myconst @ explicitly load from a nearby constant
...
myconst: .word 0x12345678
The latter two are the same, the equals trick simply asks the assembler to place the value within reach and do a pc relative load.