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x86 Assembly: strlen Procedure

Use MASM for Visual C++ Express Edition 2005 to compile this procedure.

This procedure, strlen_asm, returns the length of a C-string. For Unicode strings see wcslen_asm.

TITLE 'extern "C" unsigned strlen_asm(const char *string);'

.386P

.model FLAT

PUBLIC	_strlen_asm

_TEXT	SEGMENT
_strlen_asm PROC NEAR

	push edi
	mov  edi, DWORD PTR [esp+8] ; *string
	mov  ecx, 0FFFFFFFFh
	xor  eax, eax
	cld
	repne scasb
	xor  ecx, 0FFFFFFFFh
	dec  ecx
	mov  eax, ecx
	pop  edi
	
	ret  0
	
_strlen_asm ENDP
_TEXT	ENDS
END

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