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