forked from KolibriOS/kolibrios
40 lines
717 B
NASM
40 lines
717 B
NASM
|
bits 32
|
||
|
|
section .text
|
||
|
|
;extern "C" int asm_memcpy
|
||
|
|
; (unsigned char *dest, unsigned char *src, int len);
|
||
|
|
|
||
|
|
global asm_memcpy
|
||
|
|
|
||
|
|
times ($$-$) & 3 db 0
|
||
|
|
|
||
|
|
asm_memcpy:
|
||
|
|
|
||
|
|
pushad ; save registers
|
||
|
|
mov edi,[esp+36] ; get 1st argument
|
||
|
|
mov esi,[esp+40] ; ...2nd
|
||
|
|
mov eax,[esp+44] ; ...3rd
|
||
|
|
|
||
|
|
mov edx, eax
|
||
|
|
shr eax, 2 ; figure out how many 4 byte chunks we have
|
||
|
|
and edx, 3 ; also figure out slack
|
||
|
|
test eax, eax ; Do we have any big chunks?
|
||
|
|
push edx
|
||
|
|
jz .slack ; If not, just do slack
|
||
|
|
|
||
|
|
mov ecx,eax
|
||
|
|
|
||
|
|
rep movsd ; move 4 byte chunks
|
||
|
|
|
||
|
|
.slack:
|
||
|
|
pop ecx
|
||
|
|
rep movsb ; move 1 byte slack
|
||
|
|
|
||
|
|
popad ; clean up
|
||
|
|
ret
|
||
|
|
|
||
|
|
; --------------------------------------
|
||
|
|
|
||
|
|
%ifdef NASM_STACK_NOEXEC
|
||
|
|
section .note.GNU-stack noalloc noexec nowrite progbits
|
||
|
|
%endif
|