NetBSD/sys/lib/libkern/arch/i386/strlen.S

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/*
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* Written by J.T. Conklin <jtc@netbsd.org>.
* Public domain.
*/
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#include <machine/asm.h>
#if defined(LIBC_SCCS)
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RCSID("$NetBSD: strlen.S,v 1.5 1995/10/07 09:27:12 mycroft Exp $")
#endif
ENTRY(strlen)
pushl %edi
movl 8(%esp),%edi /* string address */
cld /* set search forward */
xorl %eax,%eax /* set search for null terminator */
movl $-1,%ecx /* set search for lots of characters */
repne /* search! */
scasb
notl %ecx /* get length by taking complement */
leal -1(%ecx),%eax /* and subtracting one */
popl %edi
ret