1/* $NetBSD: bcmp.S,v 1.6 1997/10/20 09:31:37 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#define _LOCORE /* XXX not really, just assembly-code source */ 41#include <machine/endian.h> /* LWLO/LWHI, SWLO/SWHI */ 42 43#if defined(LIBC_SCCS) && !defined(lint) 44 ASMSTR("from: @(#)bcmp.s 8.1 (Berkeley) 6/4/93") 45 ASMSTR("$NetBSD: bcmp.S,v 1.6 1997/10/20 09:31:37 jonathan Exp $") 46#endif /* LIBC_SCCS and not lint */ 47 48#ifdef ABICALLS 49 .abicalls 50#endif 51 52/* bcmp(s1, s2, n) */ 53 54 55LEAF(bcmp) 56 .set noreorder 57 blt a2, 16, small # is it worth any trouble? 58 xor v0, a0, a1 # compare low two bits of addresses 59 and v0, v0, 3 60 subu a3, zero, a1 # compute # bytes to word align address 61 bne v0, zero, unaligned # not possible to align addresses 62 and a3, a3, 3 63 64 beq a3, zero, 1f 65 subu a2, a2, a3 # subtract from remaining count 66 move v0, v1 # init v0,v1 so unmodified bytes match 67 LWHI v0, 0(a0) # read 1, 2, or 3 bytes 68 LWHI v1, 0(a1) 69 addu a1, a1, a3 70 bne v0, v1, nomatch 71 addu a0, a0, a3 721: 73 and a3, a2, ~3 # compute number of whole words left 74 subu a2, a2, a3 # which has to be >= (16-3) & ~3 75 addu a3, a3, a0 # compute ending address 762: 77 lw v0, 0(a0) # compare words 78 lw v1, 0(a1) 79 addu a0, a0, 4 80 bne v0, v1, nomatch 81 addu a1, a1, 4 82 bne a0, a3, 2b 83 nop 84 b small # finish remainder 85 nop 86unaligned: 87 beq a3, zero, 2f 88 subu a2, a2, a3 # subtract from remaining count 89 addu a3, a3, a0 # compute ending address 901: 91 lbu v0, 0(a0) # compare bytes until a1 word aligned 92 lbu v1, 0(a1) 93 addu a0, a0, 1 94 bne v0, v1, nomatch 95 addu a1, a1, 1 96 bne a0, a3, 1b 97 nop 982: 99 and a3, a2, ~3 # compute number of whole words left 100 subu a2, a2, a3 # which has to be >= (16-3) & ~3 101 addu a3, a3, a0 # compute ending address 1023: 103 LWHI v0, 0(a0) # compare words a0 unaligned, a1 aligned 104 LWLO v0, 3(a0) 105 lw v1, 0(a1) 106 addu a0, a0, 4 107 bne v0, v1, nomatch 108 addu a1, a1, 4 109 bne a0, a3, 3b 110 nop 111small: 112 ble a2, zero, match 113 addu a3, a2, a0 # compute ending address 1141: 115 lbu v0, 0(a0) 116 lbu v1, 0(a1) 117 addu a0, a0, 1 118 bne v0, v1, nomatch 119 addu a1, a1, 1 120 bne a0, a3, 1b 121 nop 122match: 123 j ra 124 move v0, zero 125nomatch: 126 j ra 127 li v0, 1 128 .set reorder 129END(bcmp) 130