1/* $NetBSD: memcmp.S,v 1.5 2013/09/07 19:06:29 chs Exp $ */ 2 3/*- 4 * Copyright (c) 1990 The Regents of the University of California. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * the Systems Programming Group of the University of Utah Computer 9 * Science Department. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36#include <machine/asm.h> 37 38#if defined(LIBC_SCCS) && !defined(lint) 39#if 0 40 RCSID("from: @(#)bcmp.s 5.1 (Berkeley) 5/12/90") 41#else 42 RCSID("$NetBSD: memcmp.S,v 1.5 2013/09/07 19:06:29 chs Exp $") 43#endif 44#endif /* LIBC_SCCS and not lint */ 45 46/* memcmp(s1, s2, n) */ 47 48#ifdef __mcoldfire__ 49#define CMPMB(a,b) movb b,%d2; cmpb a,%d2 50#define CMPMW(a,b) movw b,%d2; cmpw a,%d2 51#define CMPML(a,b) movl b,%d2; cmpl a,%d2 52#else 53#define CMPMB(a,b) cmpmb a,b 54#define CMPMW(a,b) cmpmw a,b 55#define CMPML(a,b) cmpml a,b 56#endif 57 58/* 59 * This is probably not the best we can do, but it is still 2-10 times 60 * faster than the C version in the portable gen directory. 61 * 62 * Things that might help: 63 * - longword align when possible (only on the 68020) 64 * - use nested DBcc instructions or use one and limit size to 64K 65 */ 66ENTRY(memcmp) 67 movl 4(%sp),%a0 | string 1 68 movl 8(%sp),%a1 | string 2 69 movl 12(%sp),%d0 | length 70#ifdef __mcoldfire__ 71 movl %d2,-(%sp) | save temp 72#endif 73 jeq .Lbcdone | if zero, nothing to do 74 movl %a0,%d1 75 btst #0,%d1 | string 1 address odd? 76 jeq .Lbceven | no, skip alignment 77 CMPMB((%a0)+,(%a1)+) | yes, compare a byte 78 jne .Lbcnoteq | not equal, return non-zero 79 subql #1,%d0 | adjust count 80 jeq .Lbcdone | count 0, reutrn zero 81.Lbceven: 82 movl %a1,%d1 83 btst #0,%d1 | string 2 address odd? 84 jne .Lbcbloop | yes, no hope for alignment, compare bytes 85 movl %d0,%d1 | no, both even 86 lsrl #2,%d1 | convert count to longword count 87 jeq .Lbcbloop | count 0, skip longword loop 88.Lbclloop: 89 CMPML((%a0)+,(%a1)+) | compare a longword 90 jne .Lbcnoteql | not equal, return non-zero 91 subql #1,%d1 | adjust count 92 jne .Lbclloop | still more, keep comparing 93 andl #3,%d0 | what remains 94 jeq .Lbcdone | nothing, all done 95.Lbcbloop: 96 CMPMB((%a0)+,(%a1)+) | compare a byte 97 jne .Lbcnoteq | not equal, return non-zero 98 subql #1,%d0 | adjust count 99 jne .Lbcbloop | still more, keep going 100 rts 101.Lbcnoteql: 102 subql #4,%a0 103 subql #4,%a1 104 movl #4,%d0 105 jra .Lbcbloop 106.Lbcnoteq: 107 clrl %d0 108 clrl %d1 109 movb -(%a0),%d0 110 movb -(%a1),%d1 111 subl %d1,%d0 112.Lbcdone: 113#ifdef __mcoldfire__ 114 movl (%sp)+,%sp | restore temp 115#endif 116 rts 117END(memcmp) 118