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memcmp.S revision 1.4 
      1 /*	$NetBSD: memcmp.S,v 1.4 2011/01/25 02:38:15 matt Exp $	*/
      2 /*-
      3  * Copyright (c) 1990, 1993
      4  *	The Regents of the University of California.  All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  * 3. Neither the name of the University nor the names of its contributors
     15  *    may be used to endorse or promote products derived from this software
     16  *    without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     28  * SUCH DAMAGE.
     29  */
     30 
     31 /* int memcmp(s1, s2, n) */
     32 
     33 #include "DEFS.h"
     34 
     35 #ifdef LIBC_SCCS
     36 RCSID("$NetBSD: memcmp.S,v 1.4 2011/01/25 02:38:15 matt Exp $")
     37 #endif
     38 
     39 ENTRY(memcmp, 0)
     40 	movl	12(%ap),%r0
     41 	jeql	9f
     42 	movq	4(%ap),%r1
     43 	ashl	$-2,%r0,%r3	# convert len to long words
     44 	jeql	2f
     45 1:
     46 	cmpl	(%r1)+,(%r2)+	# no "cmpq" alas
     47 	jneq	7f
     48 	sobgtr	%r3,1b
     49 2:
     50 	bicl3	$-4,%r0,%r3	# handle at most 3 extra bytes
     51 	jeql	4f
     52 3:
     53 	cmpb	(%r1)+,(%r2)+
     54 	jneq	8f
     55 	sobgtr	%r3,3b
     56 4:
     57 	clrl	%r0		# we had a match
     58 	ret
     59 7:				# backup, and do a byte compare
     60 	tstl	-(%r1)
     61 	tstl	-(%r2)
     62 	movl	$4,%r3
     63 	jbr	3b
     64 8:
     65 	movzbl	-(%r1),%r3
     66 	movzbl	-(%r2),%r4
     67 	subl3	%r4,%r3,%r0
     68 9:
     69 	ret
     70 END(memcmp)
     71