1/* $NetBSD: bzero.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 <machine/asm.h> 36__FBSDID("$FreeBSD$"); 37 38#if defined(LIBC_SCCS) && !defined(lint) 39 ASMSTR("from: @(#)bzero.s 8.1 (Berkeley) 6/4/93") 40 ASMSTR("$NetBSD: bzero.S,v 1.8 2003/08/07 16:42:16 agc Exp $") 41#endif /* LIBC_SCCS and not lint */ 42 43 44#ifdef __ABICALLS__ 45 .abicalls 46#endif 47 48/* bzero(s1, n) */ 49 50LEAF(bzero) 51 .set noreorder 52 blt a1, 12, smallclr # small amount to clear? 53 subu a3, zero, a0 # compute # bytes to word align address 54 and a3, a3, 3 55 beq a3, zero, 1f # skip if word aligned 56 subu a1, a1, a3 # subtract from remaining count 57#ifdef __MIPSEB__ 58 swl zero, 0(a0) # clear 1, 2, or 3 bytes to align 59#else 60 swr zero, 0(a0) # clear 1, 2, or 3 bytes to align 61#endif 62 addu a0, a0, a3 631: 64 and v0, a1, 3 # compute number of words left 65 subu a3, a1, v0 66 move a1, v0 67 addu a3, a3, a0 # compute ending address 682: 69 addu a0, a0, 4 # clear words 70 bne a0, a3, 2b # unrolling loop doesnt help 71 sw zero, -4(a0) # since we are limited by memory speed 72smallclr: 73 ble a1, zero, 2f 74 addu a3, a1, a0 # compute ending address 751: 76 addu a0, a0, 1 # clear bytes 77 bne a0, a3, 1b 78 sb zero, -1(a0) 792: 80 j ra 81 nop 82END(bzero) 83