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string.asm
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204 lines (126 loc) · 2.02 KB
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[BITS 32]
; Might just as well combine memcpy and memmove, since memmove supplies
; the needed functionality for memcpy.
;
;void *memcpy ( void *s1, const void *s2, size_t n );
[GLOBAL memcpy]
memcpy:
;void *memmove ( void *s1, const void *s2, size_t n );
[GLOBAL memmove]
memmove:
push ebp
mov ebp, esp
push edi
push esi
push ecx
mov edi, eax
mov esi, [ ebp + 8 ] ; 2nd parameter
mov ecx, [ ebp + 12 ] ; 3rd parameter
cld
cmp edi, esi
jc memmove_movsb
std
add edi, ecx
dec edi
add esi, ecx
dec esi
memmove_movsb:
rep movsb
pop ecx
pop esi
pop edi
pop ebp
ret
;int memcmp ( const void *s1, const void *s2, size_t n ); // Priority
[GLOBAL memcmp]
memcmp:
push ebp
mov ebp, esp
push edi
push esi
push ecx
mov edi, [ ebp + 8 ] ; 2nd parameter
mov esi, eax
mov ecx, [ ebp + 12 ] ; 3rd parameter
cld
repe cmpsb
dec edi
dec esi
xor eax, eax
lodsb
sub al, [ es:edi ]
movsx eax, al
pop ecx
pop esi
pop edi
pop ebp
ret
;int strcmp ( const char *s1, const char *s2 ); // Priority
;[GLOBAL strcmp]
;strcmp:
push ebp
mov ebp, esp
push edi
push esi
push ecx
mov edi, eax
mov esi, [ ebp + 8 ] ; 2nd parameter
mov ecx, [ ebp + 12 ] ; 3rd parameter
cld
repe cmpsb
pop ecx
pop esi
pop edi
pop ebp
ret
;int strncmp ( const char *s1, const char *s2, size_t n ); // Priority
;[GLOBAL strncmp]
;strncmp:
push ebp
mov ebp, esp
push edi
push esi
push ecx
mov edi, eax
mov esi, [ ebp + 8 ] ; 2nd parameter
mov ecx, [ ebp + 12 ] ; 3rd parameter
cld
repe cmpsb
pop ecx
pop esi
pop edi
pop ebp
ret
;void *memset ( void *s, int c, size_t n );
[GLOBAL memset]
memset:
push ebp
mov ebp, esp
push edi
push ecx
mov edi, eax
mov eax, [ ebp + 8 ] ; 2nd parameter
mov ecx, [ ebp + 12 ] ; 3rd parameter
cld
rep stosb
pop ecx
pop edi
pop ebp
ret
;size_t strlen ( const char *s );
[GLOBAL strlen]
strlen:
push edi
push ecx
mov edi, eax
xor eax, eax
mov ecx, eax
dec ecx
cld
repne scasb
dec eax
dec eax
sub eax, ecx
pop ecx
pop edi
ret