xref: /freebsd/lib/libc/i386/string/strcmp.S (revision 29ec623730f5964793e62d87a7e6bf2ec654b37e)
12ceb2ce9SGarrett Wollman/*
22ceb2ce9SGarrett Wollman * Copyright (c) 1993 Winning Strategies, Inc.
32ceb2ce9SGarrett Wollman * All rights reserved.
42ceb2ce9SGarrett Wollman *
52ceb2ce9SGarrett Wollman * Redistribution and use in source and binary forms, with or without
62ceb2ce9SGarrett Wollman * modification, are permitted provided that the following conditions
72ceb2ce9SGarrett Wollman * are met:
82ceb2ce9SGarrett Wollman * 1. Redistributions of source code must retain the above copyright
92ceb2ce9SGarrett Wollman *    notice, this list of conditions and the following disclaimer.
102ceb2ce9SGarrett Wollman * 2. Redistributions in binary form must reproduce the above copyright
112ceb2ce9SGarrett Wollman *    notice, this list of conditions and the following disclaimer in the
122ceb2ce9SGarrett Wollman *    documentation and/or other materials provided with the distribution.
132ceb2ce9SGarrett Wollman * 3. All advertising materials mentioning features or use of this software
142ceb2ce9SGarrett Wollman *    must display the following acknowledgement:
152ceb2ce9SGarrett Wollman *      This product includes software developed by Winning Strategies, Inc.
162ceb2ce9SGarrett Wollman * 4. The name of the author may not be used to endorse or promote products
172ceb2ce9SGarrett Wollman *    derived from this software withough specific prior written permission
182ceb2ce9SGarrett Wollman *
192ceb2ce9SGarrett Wollman * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
202ceb2ce9SGarrett Wollman * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
212ceb2ce9SGarrett Wollman * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
222ceb2ce9SGarrett Wollman * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
232ceb2ce9SGarrett Wollman * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
242ceb2ce9SGarrett Wollman * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
252ceb2ce9SGarrett Wollman * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
262ceb2ce9SGarrett Wollman * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
272ceb2ce9SGarrett Wollman * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
282ceb2ce9SGarrett Wollman * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
292ceb2ce9SGarrett Wollman */
302ceb2ce9SGarrett Wollman
312ceb2ce9SGarrett Wollman#if defined(LIBC_RCS) && !defined(lint)
32717d9cddSDavid Greenman	.text
337f3dea24SPeter Wemm        .asciz "$FreeBSD$"
342ceb2ce9SGarrett Wollman#endif /* LIBC_RCS and not lint */
352ceb2ce9SGarrett Wollman
36e6d808aeSPeter Wemm#include <machine/asm.h>
372ceb2ce9SGarrett Wollman
382ceb2ce9SGarrett Wollman/*
392ceb2ce9SGarrett Wollman * strcmp(s1, s2)
402ceb2ce9SGarrett Wollman *	return an integer greater than, equal to, or less than 0,
412ceb2ce9SGarrett Wollman *	according as string s1 is greater than, equal to, or less
422ceb2ce9SGarrett Wollman *	than the string s2.
432ceb2ce9SGarrett Wollman *
442ceb2ce9SGarrett Wollman * %eax - pointer to s1
452ceb2ce9SGarrett Wollman * %edx - pointer to s2
462ceb2ce9SGarrett Wollman *
472ceb2ce9SGarrett Wollman * Written by:
482ceb2ce9SGarrett Wollman *	J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
492ceb2ce9SGarrett Wollman */
502ceb2ce9SGarrett Wollman
512ceb2ce9SGarrett Wollman/*
522ceb2ce9SGarrett Wollman * I've unrolled the loop eight times: large enough to make a
532ceb2ce9SGarrett Wollman * significant difference, and small enough not to totally trash the
5429ec6237SBill Fumerola * cache.
552ceb2ce9SGarrett Wollman */
562ceb2ce9SGarrett Wollman
572ceb2ce9SGarrett WollmanENTRY(strcmp)
582ceb2ce9SGarrett Wollman	movl	0x04(%esp),%eax
592ceb2ce9SGarrett Wollman	movl	0x08(%esp),%edx
602ceb2ce9SGarrett Wollman	jmp	L2			/* Jump into the loop! */
612ceb2ce9SGarrett Wollman
622ceb2ce9SGarrett Wollman	.align	2,0x90
632ceb2ce9SGarrett WollmanL1:	incl	%eax
642ceb2ce9SGarrett Wollman	incl	%edx
652ceb2ce9SGarrett WollmanL2:	movb	(%eax),%cl
662ceb2ce9SGarrett Wollman	testb	%cl,%cl
672ceb2ce9SGarrett Wollman	je	L3
682ceb2ce9SGarrett Wollman	cmpb	%cl,(%edx)
692ceb2ce9SGarrett Wollman	jne	L3
702ceb2ce9SGarrett Wollman	incl	%eax
712ceb2ce9SGarrett Wollman	incl	%edx
722ceb2ce9SGarrett Wollman	movb	(%eax),%cl
732ceb2ce9SGarrett Wollman	testb	%cl,%cl
742ceb2ce9SGarrett Wollman	je	L3
752ceb2ce9SGarrett Wollman	cmpb	%cl,(%edx)
762ceb2ce9SGarrett Wollman	jne	L3
772ceb2ce9SGarrett Wollman	incl	%eax
782ceb2ce9SGarrett Wollman	incl	%edx
792ceb2ce9SGarrett Wollman	movb	(%eax),%cl
802ceb2ce9SGarrett Wollman	testb	%cl,%cl
812ceb2ce9SGarrett Wollman	je	L3
822ceb2ce9SGarrett Wollman	cmpb	%cl,(%edx)
832ceb2ce9SGarrett Wollman	jne	L3
842ceb2ce9SGarrett Wollman	incl	%eax
852ceb2ce9SGarrett Wollman	incl	%edx
862ceb2ce9SGarrett Wollman	movb	(%eax),%cl
872ceb2ce9SGarrett Wollman	testb	%cl,%cl
882ceb2ce9SGarrett Wollman	je	L3
892ceb2ce9SGarrett Wollman	cmpb	%cl,(%edx)
902ceb2ce9SGarrett Wollman	jne	L3
912ceb2ce9SGarrett Wollman	incl	%eax
922ceb2ce9SGarrett Wollman	incl	%edx
932ceb2ce9SGarrett Wollman	movb	(%eax),%cl
942ceb2ce9SGarrett Wollman	testb	%cl,%cl
952ceb2ce9SGarrett Wollman	je	L3
962ceb2ce9SGarrett Wollman	cmpb	%cl,(%edx)
972ceb2ce9SGarrett Wollman	jne	L3
982ceb2ce9SGarrett Wollman	incl	%eax
992ceb2ce9SGarrett Wollman	incl	%edx
1002ceb2ce9SGarrett Wollman	movb	(%eax),%cl
1012ceb2ce9SGarrett Wollman	testb	%cl,%cl
1022ceb2ce9SGarrett Wollman	je	L3
1032ceb2ce9SGarrett Wollman	cmpb	%cl,(%edx)
1042ceb2ce9SGarrett Wollman	jne	L3
1052ceb2ce9SGarrett Wollman	incl	%eax
1062ceb2ce9SGarrett Wollman	incl	%edx
1072ceb2ce9SGarrett Wollman	movb	(%eax),%cl
1082ceb2ce9SGarrett Wollman	testb	%cl,%cl
1092ceb2ce9SGarrett Wollman	je	L3
1102ceb2ce9SGarrett Wollman	cmpb	%cl,(%edx)
1112ceb2ce9SGarrett Wollman	jne	L3
1122ceb2ce9SGarrett Wollman	incl	%eax
1132ceb2ce9SGarrett Wollman	incl	%edx
1142ceb2ce9SGarrett Wollman	movb	(%eax),%cl
1152ceb2ce9SGarrett Wollman	testb	%cl,%cl
1162ceb2ce9SGarrett Wollman	je	L3
1172ceb2ce9SGarrett Wollman	cmpb	%cl,(%edx)
1182ceb2ce9SGarrett Wollman	je	L1
1192ceb2ce9SGarrett Wollman	.align 2, 0x90
1202ceb2ce9SGarrett WollmanL3:     movzbl  (%eax),%eax             /* unsigned comparison */
1212ceb2ce9SGarrett Wollman	movzbl  (%edx),%edx
1222ceb2ce9SGarrett Wollman	subl	%edx,%eax
1232ceb2ce9SGarrett Wollman	ret
124