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memcmp.S revision 1.1 
      1 /*	$NetBSD: memcmp.S,v 1.1 1996/05/19 15:57:44 ragge 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. All advertising materials mentioning features or use of this software
     15  *    must display the following acknowledgement:
     16  *	This product includes software developed by the University of
     17  *	California, Berkeley and its contributors.
     18  * 4. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  */
     34 
     35 /* int memcmp(s1, s2, n) */
     36 
     37 #include "DEFS.h"
     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