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fox32rom: Add memory compare routines

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This commit is contained in:
Ry 2022-03-25 18:03:12 -07:00
parent 6dde85a921
commit dddfd8b706
1 changed files with 58 additions and 2 deletions
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60
memory.asm
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@ -1,4 +1,4 @@
; memory copy routines ; memory copy/compare routines
; copy specified number of bytes from source pointer to destination pointer ; copy specified number of bytes from source pointer to destination pointer
; if the source and destination overlap, the behavior is undefined ; if the source and destination overlap, the behavior is undefined
@ -48,4 +48,60 @@ copy_memory_words_loop:
pop r31 pop r31
pop r1 pop r1
pop r0 pop r0
ret ret
; compare specified number of bytes from source pointer with destination pointer
; inputs:
; r0: pointer to source
; r1: pointer to destinaton
; 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 thie 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 destinaton
; 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 thie point
mov r0, 0
cmp r0, 0
compare_memory_words_not_equal:
pop r31
pop r1
pop r0
ret