xref: /freebsd-10.0-release/lib/libc/i386/string/memchr.S

/*
 * Copyright (c) 1993 Winning Strategies, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Winning Strategies, Inc.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software withough specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *	$Id: memchr.S,v 1.1 1993/12/05 13:01:47 ats Exp $
 */

#if defined(LIBC_RCS) && !defined(lint)
        .asciz "$Id: memchr.S,v 1.1 1993/12/05 13:01:47 ats Exp $"
#endif /* LIBC_RCS and not lint */

#include "DEFS.h"

/*
 * memchr (b, c, len)
 *	locates the first occurance of c in string b.
 *
 * Written by:
 *	J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
 */

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	%eax,%eax		/* clear Z flag, for len == 0 */
	cld				/* set search forward */
	repne				/* search! */
	scasb
	jnz	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