1/* $NetBSD: bcmp.S,v 1.9 2009/12/14 01:07:42 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 <machine/asm.h> 36__FBSDID("$FreeBSD$"); 37 38#define _LOCORE /* XXX not really, just assembly-code source */ 39#include <machine/endian.h> /* LWLO/LWHI, SWLO/SWHI */ 40 41#if defined(LIBC_SCCS) && !defined(lint) 42#if 0 43 ASMSTR("from: @(#)bcmp.s 8.1 (Berkeley) 6/4/93") 44#else 45 ASMSTR("$NetBSD: bcmp.S,v 1.9 2009/12/14 01:07:42 matt Exp $") 46#endif 47#endif /* LIBC_SCCS and not lint */ 48 49#ifdef __ABICALLS__ 50 .abicalls 51#endif 52 53/* bcmp(s1, s2, n) */ 54 55 56LEAF(bcmp) 57 .set noreorder 58 blt a2, 16, small # is it worth any trouble? 59 xor v0, a0, a1 # compare low two bits of addresses 60 and v0, v0, 3 61 PTR_SUBU a3, zero, a1 # compute # bytes to word align address 62 bne v0, zero, unaligned # not possible to align addresses 63 and a3, a3, 3 64 65 beq a3, zero, 1f 66 PTR_SUBU a2, a2, a3 # subtract from remaining count 67 move v0, v1 # init v0,v1 so unmodified bytes match 68 LWHI v0, 0(a0) # read 1, 2, or 3 bytes 69 LWHI v1, 0(a1) 70 PTR_ADDU a1, a1, a3 71 bne v0, v1, nomatch 72 PTR_ADDU a0, a0, a3 731: 74 and a3, a2, ~3 # compute number of whole words left 75 PTR_SUBU a2, a2, a3 # which has to be >= (16-3) & ~3 76 PTR_ADDU a3, a3, a0 # compute ending address 772: 78 lw v0, 0(a0) # compare words 79 lw v1, 0(a1) 80 PTR_ADDU a0, a0, 4 81 bne v0, v1, nomatch 82 PTR_ADDU a1, a1, 4 83 bne a0, a3, 2b 84 nop 85 b small # finish remainder 86 nop 87unaligned: 88 beq a3, zero, 2f 89 PTR_SUBU a2, a2, a3 # subtract from remaining count 90 PTR_ADDU a3, a3, a0 # compute ending address 911: 92 lbu v0, 0(a0) # compare bytes until a1 word aligned 93 lbu v1, 0(a1) 94 PTR_ADDU a0, a0, 1 95 bne v0, v1, nomatch 96 PTR_ADDU a1, a1, 1 97 bne a0, a3, 1b 98 nop 992: 100 and a3, a2, ~3 # compute number of whole words left 101 PTR_SUBU a2, a2, a3 # which has to be >= (16-3) & ~3 102 PTR_ADDU a3, a3, a0 # compute ending address 1033: 104 LWHI v0, 0(a0) # compare words a0 unaligned, a1 aligned 105 LWLO v0, 3(a0) 106 lw v1, 0(a1) 107 PTR_ADDU a0, a0, 4 108 bne v0, v1, nomatch 109 PTR_ADDU a1, a1, 4 110 bne a0, a3, 3b 111 nop 112small: 113 ble a2, zero, match 114 PTR_ADDU a3, a2, a0 # compute ending address 1151: 116 lbu v0, 0(a0) 117 lbu v1, 0(a1) 118 PTR_ADDU a0, a0, 1 119 bne v0, v1, nomatch 120 PTR_ADDU a1, a1, 1 121 bne a0, a3, 1b 122 nop 123match: 124 j ra 125 move v0, zero 126nomatch: 127 j ra 128 li v0, 1 129 .set reorder 130END(bcmp) 131