fox32rom/memory.asm
jn a6be83b99e Fix a bunch of typos
No functional change.
2023-01-21 11:41:14 +01:00

108 lines
2.1 KiB
NASM

; memory copy/compare routines
; copy specified number of bytes from source pointer to destination pointer
; if the source and destination overlap, the behavior is undefined
; inputs:
; r0: pointer to source
; r1: pointer to destination
; r2: number of bytes to copy
; outputs:
; none
copy_memory_bytes:
push r0
push r1
push r31
mov r31, r2
copy_memory_bytes_loop:
mov.8 [r1], [r0]
inc r0
inc r1
loop copy_memory_bytes_loop
pop r31
pop r1
pop r0
ret
; copy specified number of words from source pointer to destination pointer
; if the source and destination overlap, the behavior is undefined
; inputs:
; r0: pointer to source
; r1: pointer to destination
; r2: number of words to copy
; outputs:
; none
copy_memory_words:
push r0
push r1
push r31
mov r31, r2
copy_memory_words_loop:
mov [r1], [r0]
add r0, 4
add r1, 4
loop copy_memory_words_loop
pop r31
pop r1
pop r0
ret
; compare specified number of bytes from source pointer with destination pointer
; inputs:
; r0: pointer to source
; r1: pointer to destination
; r2: number of bytes to compare
; outputs:
; Z flag
compare_memory_bytes:
push r0
push r1
push r31
mov r31, r2
compare_memory_bytes_loop:
cmp.8 [r1], [r0]
ifnz jmp compare_memory_bytes_not_equal
inc r0
inc r1
loop compare_memory_bytes_loop
; set Z flag if we reach this point
mov r0, 0
cmp r0, 0
compare_memory_bytes_not_equal:
pop r31
pop r1
pop r0
ret
; compare specified number of words from source pointer with destination pointer
; inputs:
; r0: pointer to source
; r1: pointer to destination
; r2: number of words to compare
; outputs:
; Z flag
compare_memory_words:
push r0
push r1
push r31
mov r31, r2
compare_memory_words_loop:
cmp [r1], [r0]
ifnz jmp compare_memory_words_not_equal
add r0, 4
add r1, 4
loop compare_memory_words_loop
; set Z flag if we reach this point
mov r0, 0
cmp r0, 0
compare_memory_words_not_equal:
pop r31
pop r1
pop r0
ret