Implementing simple sort algorithms in ARM Assembly (part 1)

A while back I started to learn some ARM assembly on the Raspberry Pi (out of curiosity, for no other better reason). I thought it would be interesting to couple this with re-learning some of the basic/standard/common algorithm at the same time, such as common sort algorithms.

So as my first step, since this is turning out to be far more work than I expected (!), here’s my ARM ASM source so far to iterate through a list of 4 byte integer values and print the values to the console using C’s printf. I’ll post further updates as I make progress:

[code]
.global main
main:
push {ip, lr}
MOV R6, #0 @offset to data
loop:
LDR R0, =output @load addr of output string
LDR R5, =nums @ addr of string to R5
LDR R4,[R5,R6] @load current num from R5 with offset R6
MOV R1,R4 @move num for output
BL printf
CMP R6,#16 @ 0 plus 4*4bytes for 5 entries in array
ADD R6,R6, #4 @inc offset by 4 bytes
BNE loop
_exit:
POP {ip, lr}
MOV R1, #0
MOV R7, #1
SWI 0
nums:
.word 5,2,7,1,8
.data
output:
.asciz "%d\n"
[/code]

I’m sure there’s better ways I can approach this limited code so far, but I’ll come back and revisit this again later. If anyone wants to pull or browse the source so far (and other snippets), it’s on github here: https://github.com/kevinhooke/learning-arm-asm

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