62 lines
1.2 KiB
NASM
62 lines
1.2 KiB
NASM
; string copy/compare routines
|
|
|
|
; copy string from source pointer to destination pointer
|
|
; if the source and destination overlap, the behavior is undefined
|
|
; inputs:
|
|
; r0: pointer to source
|
|
; r1: pointer to destinaton
|
|
; outputs:
|
|
; none
|
|
copy_string:
|
|
push r0
|
|
push r1
|
|
push r2
|
|
|
|
copy_string_loop:
|
|
mov.8 r2, [r0]
|
|
mov.8 [r1], r2
|
|
inc r0
|
|
inc r1
|
|
cmp.8 r2, 0
|
|
ifnz jmp copy_string_loop
|
|
|
|
pop r2
|
|
pop r1
|
|
pop r0
|
|
ret
|
|
|
|
; compare string from source pointer with destination pointer
|
|
; inputs:
|
|
; r0: pointer to source
|
|
; r1: pointer to destinaton
|
|
; outputs:
|
|
; Z flag
|
|
compare_string:
|
|
push r0
|
|
push r1
|
|
compare_string_loop:
|
|
; check if the strings match
|
|
cmp.8 [r0], [r1]
|
|
ifnz jmp compare_string_not_equal
|
|
|
|
; if this is the end of string 1, then this must also be the end of string 2
|
|
; the cmp above alredy ensured that both strings have a null-terminator here
|
|
cmp.8 [r0], 0
|
|
ifz jmp compare_string_equal
|
|
|
|
inc r0
|
|
inc r1
|
|
jmp compare_string_loop
|
|
compare_string_not_equal:
|
|
; Z flag is already cleared at this point
|
|
pop r1
|
|
pop r0
|
|
ret
|
|
compare_string_equal:
|
|
; set Z flag
|
|
mov r0, 0
|
|
cmp r0, 0
|
|
pop r1
|
|
pop r0
|
|
ret
|