memcmp.S revision 1.1
11.1Schristos/* $NetBSD: memcmp.S,v 1.1 2005/12/20 19:28:49 christos Exp $ */ 21.1Schristos 31.1Schristos/*- 41.1Schristos * Copyright (c) 1990 The Regents of the University of California. 51.1Schristos * All rights reserved. 61.1Schristos * 71.1Schristos * This code is derived from software contributed to Berkeley by 81.1Schristos * the Systems Programming Group of the University of Utah Computer 91.1Schristos * Science Department. 101.1Schristos * 111.1Schristos * Redistribution and use in source and binary forms, with or without 121.1Schristos * modification, are permitted provided that the following conditions 131.1Schristos * are met: 141.1Schristos * 1. Redistributions of source code must retain the above copyright 151.1Schristos * notice, this list of conditions and the following disclaimer. 161.1Schristos * 2. Redistributions in binary form must reproduce the above copyright 171.1Schristos * notice, this list of conditions and the following disclaimer in the 181.1Schristos * documentation and/or other materials provided with the distribution. 191.1Schristos * 3. Neither the name of the University nor the names of its contributors 201.1Schristos * may be used to endorse or promote products derived from this software 211.1Schristos * without specific prior written permission. 221.1Schristos * 231.1Schristos * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 241.1Schristos * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 251.1Schristos * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 261.1Schristos * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 271.1Schristos * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 281.1Schristos * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 291.1Schristos * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 301.1Schristos * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 311.1Schristos * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 321.1Schristos * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 331.1Schristos * SUCH DAMAGE. 341.1Schristos */ 351.1Schristos 361.1Schristos#include <machine/asm.h> 371.1Schristos 381.1Schristos#if defined(LIBC_SCCS) && !defined(lint) 391.1Schristos#if 0 401.1Schristos RCSID("from: @(#)bcmp.s 5.1 (Berkeley) 5/12/90") 411.1Schristos#else 421.1Schristos RCSID("$NetBSD: memcmp.S,v 1.1 2005/12/20 19:28:49 christos Exp $") 431.1Schristos#endif 441.1Schristos#endif /* LIBC_SCCS and not lint */ 451.1Schristos 461.1Schristos/* memcmp(s1, s2, n) */ 471.1Schristos 481.1Schristos/* 491.1Schristos * This is probably not the best we can do, but it is still 2-10 times 501.1Schristos * faster than the C version in the portable gen directory. 511.1Schristos * 521.1Schristos * Things that might help: 531.1Schristos * - longword align when possible (only on the 68020) 541.1Schristos * - use nested DBcc instructions or use one and limit size to 64K 551.1Schristos */ 561.1SchristosENTRY(memcmp) 571.1Schristos movl %sp@(4),%a0 | string 1 581.1Schristos movl %sp@(8),%a1 | string 2 591.1Schristos movl %sp@(12),%d0 | length 601.1Schristos jeq bcdone | if zero, nothing to do 611.1Schristos movl %a0,%d1 621.1Schristos btst #0,%d1 | string 1 address odd? 631.1Schristos jeq bceven | no, skip alignment 641.1Schristos cmpmb %a0@+,%a1@+ | yes, compare a byte 651.1Schristos jne bcnoteq | not equal, return non-zero 661.1Schristos subql #1,%d0 | adjust count 671.1Schristos jeq bcdone | count 0, reutrn zero 681.1Schristosbceven: 691.1Schristos movl %a1,%d1 701.1Schristos btst #0,%d1 | string 2 address odd? 711.1Schristos jne bcbloop | yes, no hope for alignment, compare bytes 721.1Schristos movl %d0,%d1 | no, both even 731.1Schristos lsrl #2,%d1 | convert count to longword count 741.1Schristos jeq bcbloop | count 0, skip longword loop 751.1Schristosbclloop: 761.1Schristos cmpml %a0@+,%a1@+ | compare a longword 771.1Schristos jne bcnoteql | not equal, return non-zero 781.1Schristos subql #1,%d1 | adjust count 791.1Schristos jne bclloop | still more, keep comparing 801.1Schristos andl #3,%d0 | what remains 811.1Schristos jeq bcdone | nothing, all done 821.1Schristosbcbloop: 831.1Schristos cmpmb %a0@+,%a1@+ | compare a byte 841.1Schristos jne bcnoteq | not equal, return non-zero 851.1Schristos subql #1,%d0 | adjust count 861.1Schristos jne bcbloop | still more, keep going 871.1Schristos rts 881.1Schristosbcnoteql: 891.1Schristos subql #4,%a0 901.1Schristos subql #4,%a1 911.1Schristos movl #4,%d0 921.1Schristos jra bcbloop 931.1Schristosbcnoteq: 941.1Schristos clrl %d0 951.1Schristos clrl %d1 961.1Schristos movb %a0@-,%d0 971.1Schristos movb %a1@-,%d1 981.1Schristos subl %d1,%d0 991.1Schristosbcdone: 1001.1Schristos rts 101