summaryrefslogtreecommitdiff
path: root/sys/lib/libkern/arch/i386/memchr.S
blob: 43f7a91e0a119389585b605937942c0e2a516f09 (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
/*	$OpenBSD: memchr.S,v 1.1 1997/11/04 19:08:06 chuck Exp $	*/

/*
 * Written by J.T. Conklin <jtc@netbsd.org>.
 * Public domain.
 */

#include <machine/asm.h>

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