summaryrefslogtreecommitdiff
path: root/lib/libc/arch/i386/string/memchr.S
blob: 583b0e1748d29808a08dc26292461ef7e5f65930 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
/*
 * Written by J.T. Conklin <jtc@netbsd.org>.
 * Public domain.
 */

#include <machine/asm.h>

#if defined(LIBC_SCCS)
	.text
	.asciz "$OpenBSD: memchr.S,v 1.2 1996/08/19 08:13:01 tholo Exp $"
#endif

ENTRY(memchr)
	pushl	%edi
	movl	8(%esp),%edi		/* string address */
	movl	12(%esp),%eax		/* set character to search for */
	movl	16(%esp),%ecx		/* set length of search */
	testl	%ecx,%ecx		/* test for len == 0 */
	jz	L1
	cld				/* set search forward */
	repne				/* search! */
	scasb
	jne	L1			/* scan failed, return null */
	leal	-1(%edi),%eax		/* adjust result of scan */
	popl	%edi
	ret
	.align 2,0x90
L1:	xorl	%eax,%eax
	popl	%edi
	ret