1*9b9d2a55Sguenther/* $OpenBSD: bcmp.S,v 1.5 2015/08/31 02:53:56 guenther Exp $ */ 20eea0d08Spefo/*- 30eea0d08Spefo * Copyright (c) 1991, 1993 40eea0d08Spefo * The Regents of the University of California. All rights reserved. 50eea0d08Spefo * 60eea0d08Spefo * This code is derived from software contributed to Berkeley by 70eea0d08Spefo * Ralph Campbell. 80eea0d08Spefo * 90eea0d08Spefo * Redistribution and use in source and binary forms, with or without 100eea0d08Spefo * modification, are permitted provided that the following conditions 110eea0d08Spefo * are met: 120eea0d08Spefo * 1. Redistributions of source code must retain the above copyright 130eea0d08Spefo * notice, this list of conditions and the following disclaimer. 140eea0d08Spefo * 2. Redistributions in binary form must reproduce the above copyright 150eea0d08Spefo * notice, this list of conditions and the following disclaimer in the 160eea0d08Spefo * documentation and/or other materials provided with the distribution. 170eea0d08Spefo * 3. Neither the name of the University nor the names of its contributors 180eea0d08Spefo * may be used to endorse or promote products derived from this software 190eea0d08Spefo * without specific prior written permission. 200eea0d08Spefo * 210eea0d08Spefo * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 220eea0d08Spefo * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 230eea0d08Spefo * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 240eea0d08Spefo * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 250eea0d08Spefo * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 260eea0d08Spefo * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 270eea0d08Spefo * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 280eea0d08Spefo * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 290eea0d08Spefo * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 300eea0d08Spefo * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 310eea0d08Spefo * SUCH DAMAGE. 320eea0d08Spefo */ 330eea0d08Spefo 34*9b9d2a55Sguenther#include "SYS.h" 350eea0d08Spefo 360eea0d08Spefo/* bcmp(s1, s2, n) */ 370eea0d08Spefo 385738bc62SpefoLEAF(bcmp, 0) 390eea0d08Spefo .set noreorder 400eea0d08Spefo blt a2, 16, small # is it worth any trouble? 410eea0d08Spefo xor v0, a0, a1 # compare low two bits of addresses 420eea0d08Spefo and v0, v0, 3 4350027fe1Smiod dsubu a3, zero, a1 # compute # bytes to word align address 440eea0d08Spefo bne v0, zero, unaligned # not possible to align addresses 450eea0d08Spefo and a3, a3, 3 460eea0d08Spefo 470eea0d08Spefo beq a3, zero, 1f 4850027fe1Smiod dsubu a2, a2, a3 # subtract from remaining count 490eea0d08Spefo move v0, v1 # init v0,v1 so unmodified bytes match 500eea0d08Spefo LWHI v0, 0(a0) # read 1, 2, or 3 bytes 510eea0d08Spefo LWHI v1, 0(a1) 5250027fe1Smiod daddu a1, a1, a3 530eea0d08Spefo bne v0, v1, nomatch 5450027fe1Smiod daddu a0, a0, a3 550eea0d08Spefo1: 560eea0d08Spefo and a3, a2, ~3 # compute number of whole words left 5750027fe1Smiod dsubu a2, a2, a3 # which has to be >= (16-3) & ~3 5850027fe1Smiod daddu a3, a3, a0 # compute ending address 590eea0d08Spefo2: 600eea0d08Spefo lw v0, 0(a0) # compare words 610eea0d08Spefo lw v1, 0(a1) 6250027fe1Smiod daddu a0, a0, 4 630eea0d08Spefo bne v0, v1, nomatch 6450027fe1Smiod daddu a1, a1, 4 650eea0d08Spefo bne a0, a3, 2b 660eea0d08Spefo nop 670eea0d08Spefo b small # finish remainder 680eea0d08Spefo nop 690eea0d08Spefounaligned: 700eea0d08Spefo beq a3, zero, 2f 7150027fe1Smiod dsubu a2, a2, a3 # subtract from remaining count 7250027fe1Smiod daddu a3, a3, a0 # compute ending address 730eea0d08Spefo1: 740eea0d08Spefo lbu v0, 0(a0) # compare bytes until a1 word aligned 750eea0d08Spefo lbu v1, 0(a1) 7650027fe1Smiod daddu a0, a0, 1 770eea0d08Spefo bne v0, v1, nomatch 7850027fe1Smiod daddu a1, a1, 1 790eea0d08Spefo bne a0, a3, 1b 800eea0d08Spefo nop 810eea0d08Spefo2: 820eea0d08Spefo and a3, a2, ~3 # compute number of whole words left 8350027fe1Smiod dsubu a2, a2, a3 # which has to be >= (16-3) & ~3 8450027fe1Smiod daddu a3, a3, a0 # compute ending address 850eea0d08Spefo3: 860eea0d08Spefo LWHI v0, 0(a0) # compare words a0 unaligned, a1 aligned 870eea0d08Spefo LWLO v0, 3(a0) 880eea0d08Spefo lw v1, 0(a1) 8950027fe1Smiod daddu a0, a0, 4 900eea0d08Spefo bne v0, v1, nomatch 9150027fe1Smiod daddu a1, a1, 4 920eea0d08Spefo bne a0, a3, 3b 930eea0d08Spefo nop 940eea0d08Spefosmall: 950eea0d08Spefo ble a2, zero, match 9650027fe1Smiod daddu a3, a2, a0 # compute ending address 970eea0d08Spefo1: 980eea0d08Spefo lbu v0, 0(a0) 990eea0d08Spefo lbu v1, 0(a1) 10050027fe1Smiod daddu a0, a0, 1 1010eea0d08Spefo bne v0, v1, nomatch 10250027fe1Smiod daddu a1, a1, 1 1030eea0d08Spefo bne a0, a3, 1b 1040eea0d08Spefo nop 1050eea0d08Spefomatch: 1060eea0d08Spefo j ra 1070eea0d08Spefo move v0, zero 1080eea0d08Spefonomatch: 1090eea0d08Spefo j ra 1100eea0d08Spefo li v0, 1 1110eea0d08Spefo .set reorder 112*9b9d2a55SguentherEND_WEAK(bcmp) 113