1/* $NetBSD: bcmp.S,v 1.4 1996/09/16 18:11:17 jonathan Exp $ */ 2 3/*- 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Ralph Campbell. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39#include <machine/machAsmDefs.h> 40 41#if defined(LIBC_SCCS) && !defined(lint) 42 ASMSTR("from: @(#)bcmp.s 8.1 (Berkeley) 6/4/93") 43 ASMSTR("$NetBSD: bcmp.S,v 1.4 1996/09/16 18:11:17 jonathan Exp $") 44#endif /* LIBC_SCCS and not lint */ 45 46/* bcmp(s1, s2, n) */ 47 48#ifdef MIPSEL 49# define LWHI lwr 50# define LWLO lwl 51# define SWHI swr 52# define SWLO swl 53#endif 54#ifdef MIPSEB 55# define LWHI lwl 56# define LWLO lwr 57# define SWHI swl 58# define SWLO swr 59#endif 60 61LEAF(bcmp) 62 .set noreorder 63 blt a2, 16, small # is it worth any trouble? 64 xor v0, a0, a1 # compare low two bits of addresses 65 and v0, v0, 3 66 subu a3, zero, a1 # compute # bytes to word align address 67 bne v0, zero, unaligned # not possible to align addresses 68 and a3, a3, 3 69 70 beq a3, zero, 1f 71 subu a2, a2, a3 # subtract from remaining count 72 move v0, v1 # init v0,v1 so unmodified bytes match 73 LWHI v0, 0(a0) # read 1, 2, or 3 bytes 74 LWHI v1, 0(a1) 75 addu a1, a1, a3 76 bne v0, v1, nomatch 77 addu a0, a0, a3 781: 79 and a3, a2, ~3 # compute number of whole words left 80 subu a2, a2, a3 # which has to be >= (16-3) & ~3 81 addu a3, a3, a0 # compute ending address 822: 83 lw v0, 0(a0) # compare words 84 lw v1, 0(a1) 85 addu a0, a0, 4 86 bne v0, v1, nomatch 87 addu a1, a1, 4 88 bne a0, a3, 2b 89 nop 90 b small # finish remainder 91 nop 92unaligned: 93 beq a3, zero, 2f 94 subu a2, a2, a3 # subtract from remaining count 95 addu a3, a3, a0 # compute ending address 961: 97 lbu v0, 0(a0) # compare bytes until a1 word aligned 98 lbu v1, 0(a1) 99 addu a0, a0, 1 100 bne v0, v1, nomatch 101 addu a1, a1, 1 102 bne a0, a3, 1b 103 nop 1042: 105 and a3, a2, ~3 # compute number of whole words left 106 subu a2, a2, a3 # which has to be >= (16-3) & ~3 107 addu a3, a3, a0 # compute ending address 1083: 109 LWHI v0, 0(a0) # compare words a0 unaligned, a1 aligned 110 LWLO v0, 3(a0) 111 lw v1, 0(a1) 112 addu a0, a0, 4 113 bne v0, v1, nomatch 114 addu a1, a1, 4 115 bne a0, a3, 3b 116 nop 117small: 118 ble a2, zero, match 119 addu a3, a2, a0 # compute ending address 1201: 121 lbu v0, 0(a0) 122 lbu v1, 0(a1) 123 addu a0, a0, 1 124 bne v0, v1, nomatch 125 addu a1, a1, 1 126 bne a0, a3, 1b 127 nop 128match: 129 j ra 130 move v0, zero 131nomatch: 132 j ra 133 li v0, 1 134 .set reorder 135END(bcmp) 136