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index.S revision 1.6 
      1 /*
      2  * Copyright (c) 1993 Winning Strategies, Inc.
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *      This product includes software developed by Winning Strategies, Inc.
     16  * 4. The name of the author may not be used to endorse or promote products
     17  *    derived from this software without specific prior written permission
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  *
     30  *	$Id: index.S,v 1.6 1994/03/12 01:40:00 jtc Exp $
     31  */
     32 
     33 #include <machine/asm.h>
     34 
     35 #if defined(LIBC_SCCS)
     36 	RCSID("$Id: index.S,v 1.6 1994/03/12 01:40:00 jtc Exp $")
     37 #endif
     38 
     39 /*
     40  * strchr(s, c)
     41  * index(s, c)
     42  *	return a pointer to the first occurance of the character c in
     43  *	string s, or NULL if c does not occur in the string.
     44  *
     45  * %edx - pointer iterating through string
     46  * %eax - pointer to first occurance of 'c'
     47  * %cl  - character we're comparing against
     48  * %bl  - character at %edx
     49  *
     50  * Written by:
     51  *	J.T. Conklin (jtc (at) wimsey.com), Winning Strategies, Inc.
     52  */
     53 
     54 #ifdef STRCHR
     55 ENTRY(strchr)
     56 #else
     57 ENTRY(index)
     58 #endif
     59 	pushl	%ebx
     60 	movl	8(%esp),%eax
     61 	movb	12(%esp),%cl
     62 	.align 2,0x90
     63 L1:
     64 	movb	(%eax),%bl
     65 	cmpb	%bl,%cl			/* found char??? */
     66 	je 	L2
     67 	incl	%eax
     68 	testb	%bl,%bl			/* null terminator??? */
     69 	jnz	L1
     70 	xorl	%eax,%eax
     71 L2:
     72 	popl	%ebx
     73 	ret
     74