1/* $NetBSD: bcmp.S,v 1.8.46.2 2009/08/18 06:55:48 matt 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35#include <mips/asm.h> 36#define _LOCORE /* XXX not really, just assembly-code source */ 37#include <machine/endian.h> /* LWLO/LWHI, SWLO/SWHI */ 38 39#if defined(LIBC_SCCS) && !defined(lint) 40#if 0 41 RCSID("from: @(#)bcmp.s 8.1 (Berkeley) 6/4/93") 42#else 43 RCSID("$NetBSD: bcmp.S,v 1.8.46.2 2009/08/18 06:55:48 matt Exp $") 44#endif 45#endif /* LIBC_SCCS and not lint */ 46 47/* bcmp(s1, s2, n) */ 48 49 50LEAF(bcmp) 51 .set noreorder 52 blt a2, 16, small # is it worth any trouble? 53 xor v0, a0, a1 # compare low two bits of addresses 54 and v0, v0, 3 55 PTR_SUBU a3, zero, a1 # compute # bytes to word align address 56 bne v0, zero, unaligned # not possible to align addresses 57 and a3, a3, 3 58 59 beq a3, zero, 1f 60 PTR_SUBU a2, a2, a3 # subtract from remaining count 61 move v0, v1 # init v0,v1 so unmodified bytes match 62 LWHI v0, 0(a0) # read 1, 2, or 3 bytes 63 LWHI v1, 0(a1) 64 PTR_ADDU a1, a1, a3 65 bne v0, v1, nomatch 66 PTR_ADDU a0, a0, a3 671: 68 and a3, a2, ~3 # compute number of whole words left 69 PTR_SUBU a2, a2, a3 # which has to be >= (16-3) & ~3 70 PTR_ADDU a3, a3, a0 # compute ending address 712: 72 lw v0, 0(a0) # compare words 73 lw v1, 0(a1) 74 PTR_ADDU a0, a0, 4 75 bne v0, v1, nomatch 76 PTR_ADDU a1, a1, 4 77 bne a0, a3, 2b 78 nop 79 b small # finish remainder 80 nop 81unaligned: 82 beq a3, zero, 2f 83 PTR_SUBU a2, a2, a3 # subtract from remaining count 84 PTR_ADDU a3, a3, a0 # compute ending address 851: 86 lbu v0, 0(a0) # compare bytes until a1 word aligned 87 lbu v1, 0(a1) 88 PTR_ADDU a0, a0, 1 89 bne v0, v1, nomatch 90 PTR_ADDU a1, a1, 1 91 bne a0, a3, 1b 92 nop 932: 94 and a3, a2, ~3 # compute number of whole words left 95 PTR_SUBU a2, a2, a3 # which has to be >= (16-3) & ~3 96 PTR_ADDU a3, a3, a0 # compute ending address 973: 98 LWHI v0, 0(a0) # compare words a0 unaligned, a1 aligned 99 LWLO v0, 3(a0) 100 lw v1, 0(a1) 101 PTR_ADDU a0, a0, 4 102 bne v0, v1, nomatch 103 PTR_ADDU a1, a1, 4 104 bne a0, a3, 3b 105 nop 106small: 107 ble a2, zero, match 108 PTR_ADDU a3, a2, a0 # compute ending address 1091: 110 lbu v0, 0(a0) 111 lbu v1, 0(a1) 112 PTR_ADDU a0, a0, 1 113 bne v0, v1, nomatch 114 PTR_ADDU a1, a1, 1 115 bne a0, a3, 1b 116 nop 117match: 118 j ra 119 move v0, zero 120nomatch: 121 j ra 122 li v0, 1 123 .set reorder 124END(bcmp) 125