1/* $NetBSD: bcmp.S,v 1.5 1996/09/17 01:32:30 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 <mips/asm.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 1.5 1996/09/17 01:32:30 jonathan Exp $") 44#endif /* LIBC_SCCS and not lint */ 45 46#ifdef ABICALLS 47 .abicalls 48#endif 49 50/* bcmp(s1, s2, n) */ 51 52#ifdef MIPSEL 53# define LWHI lwr 54# define LWLO lwl 55# define SWHI swr 56# define SWLO swl 57#endif 58#ifdef MIPSEB 59# define LWHI lwl 60# define LWLO lwr 61# define SWHI swl 62# define SWLO swr 63#endif 64 65LEAF(bcmp) 66 .set noreorder 67 blt a2, 16, small # is it worth any trouble? 68 xor v0, a0, a1 # compare low two bits of addresses 69 and v0, v0, 3 70 subu a3, zero, a1 # compute # bytes to word align address 71 bne v0, zero, unaligned # not possible to align addresses 72 and a3, a3, 3 73 74 beq a3, zero, 1f 75 subu a2, a2, a3 # subtract from remaining count 76 move v0, v1 # init v0,v1 so unmodified bytes match 77 LWHI v0, 0(a0) # read 1, 2, or 3 bytes 78 LWHI v1, 0(a1) 79 addu a1, a1, a3 80 bne v0, v1, nomatch 81 addu a0, a0, a3 821: 83 and a3, a2, ~3 # compute number of whole words left 84 subu a2, a2, a3 # which has to be >= (16-3) & ~3 85 addu a3, a3, a0 # compute ending address 862: 87 lw v0, 0(a0) # compare words 88 lw v1, 0(a1) 89 addu a0, a0, 4 90 bne v0, v1, nomatch 91 addu a1, a1, 4 92 bne a0, a3, 2b 93 nop 94 b small # finish remainder 95 nop 96unaligned: 97 beq a3, zero, 2f 98 subu a2, a2, a3 # subtract from remaining count 99 addu a3, a3, a0 # compute ending address 1001: 101 lbu v0, 0(a0) # compare bytes until a1 word aligned 102 lbu v1, 0(a1) 103 addu a0, a0, 1 104 bne v0, v1, nomatch 105 addu a1, a1, 1 106 bne a0, a3, 1b 107 nop 1082: 109 and a3, a2, ~3 # compute number of whole words left 110 subu a2, a2, a3 # which has to be >= (16-3) & ~3 111 addu a3, a3, a0 # compute ending address 1123: 113 LWHI v0, 0(a0) # compare words a0 unaligned, a1 aligned 114 LWLO v0, 3(a0) 115 lw v1, 0(a1) 116 addu a0, a0, 4 117 bne v0, v1, nomatch 118 addu a1, a1, 4 119 bne a0, a3, 3b 120 nop 121small: 122 ble a2, zero, match 123 addu a3, a2, a0 # compute ending address 1241: 125 lbu v0, 0(a0) 126 lbu v1, 0(a1) 127 addu a0, a0, 1 128 bne v0, v1, nomatch 129 addu a1, a1, 1 130 bne a0, a3, 1b 131 nop 132match: 133 j ra 134 move v0, zero 135nomatch: 136 j ra 137 li v0, 1 138 .set reorder 139END(bcmp) 140