1/* $NetBSD: bcmp.S,v 1.8 2003/08/07 16:42:16 agc 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 ASMSTR("from: @(#)bcmp.s 8.1 (Berkeley) 6/4/93") 41 ASMSTR("$NetBSD: bcmp.S,v 1.8 2003/08/07 16:42:16 agc Exp $") 42#endif /* LIBC_SCCS and not lint */ 43 44#ifdef __ABICALLS__ 45 .abicalls 46#endif 47 48/* bcmp(s1, s2, n) */ 49 50 51LEAF(bcmp) 52 .set noreorder 53 blt a2, 16, small # is it worth any trouble? 54 xor v0, a0, a1 # compare low two bits of addresses 55 and v0, v0, 3 56 subu a3, zero, a1 # compute # bytes to word align address 57 bne v0, zero, unaligned # not possible to align addresses 58 and a3, a3, 3 59 60 beq a3, zero, 1f 61 subu a2, a2, a3 # subtract from remaining count 62 move v0, v1 # init v0,v1 so unmodified bytes match 63 LWHI v0, 0(a0) # read 1, 2, or 3 bytes 64 LWHI v1, 0(a1) 65 addu a1, a1, a3 66 bne v0, v1, nomatch 67 addu a0, a0, a3 681: 69 and a3, a2, ~3 # compute number of whole words left 70 subu a2, a2, a3 # which has to be >= (16-3) & ~3 71 addu a3, a3, a0 # compute ending address 722: 73 lw v0, 0(a0) # compare words 74 lw v1, 0(a1) 75 addu a0, a0, 4 76 bne v0, v1, nomatch 77 addu a1, a1, 4 78 bne a0, a3, 2b 79 nop 80 b small # finish remainder 81 nop 82unaligned: 83 beq a3, zero, 2f 84 subu a2, a2, a3 # subtract from remaining count 85 addu a3, a3, a0 # compute ending address 861: 87 lbu v0, 0(a0) # compare bytes until a1 word aligned 88 lbu v1, 0(a1) 89 addu a0, a0, 1 90 bne v0, v1, nomatch 91 addu a1, a1, 1 92 bne a0, a3, 1b 93 nop 942: 95 and a3, a2, ~3 # compute number of whole words left 96 subu a2, a2, a3 # which has to be >= (16-3) & ~3 97 addu a3, a3, a0 # compute ending address 983: 99 LWHI v0, 0(a0) # compare words a0 unaligned, a1 aligned 100 LWLO v0, 3(a0) 101 lw v1, 0(a1) 102 addu a0, a0, 4 103 bne v0, v1, nomatch 104 addu a1, a1, 4 105 bne a0, a3, 3b 106 nop 107small: 108 ble a2, zero, match 109 addu a3, a2, a0 # compute ending address 1101: 111 lbu v0, 0(a0) 112 lbu v1, 0(a1) 113 addu a0, a0, 1 114 bne v0, v1, nomatch 115 addu a1, a1, 1 116 bne a0, a3, 1b 117 nop 118match: 119 j ra 120 move v0, zero 121nomatch: 122 j ra 123 li v0, 1 124 .set reorder 125END(bcmp) 126