1/* $NetBSD: bzero.S,v 1.5 1996/09/17 01:32:33 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 41#if defined(LIBC_SCCS) && !defined(lint) 42 ASMSTR("from: @(#)bzero.s 8.1 (Berkeley) 6/4/93") 43 ASMSTR("$NetBSD: bzero.S,v 1.5 1996/09/17 01:32:33 jonathan Exp $") 44#endif /* LIBC_SCCS and not lint */ 45 46#ifdef ABICALLS 47 .abicalls 48#endif 49 50/* bzero(s1, n) */ 51 52LEAF(bzero) 53 .set noreorder 54 blt a1, 12, smallclr # small amount to clear? 55 subu a3, zero, a0 # compute # bytes to word align address 56 and a3, a3, 3 57 beq a3, zero, 1f # skip if word aligned 58 subu a1, a1, a3 # subtract from remaining count 59 swr zero, 0(a0) # clear 1, 2, or 3 bytes to align 60 addu a0, a0, a3 611: 62 and v0, a1, 3 # compute number of words left 63 subu a3, a1, v0 64 move a1, v0 65 addu a3, a3, a0 # compute ending address 662: 67 addu a0, a0, 4 # clear words 68 bne a0, a3, 2b # unrolling loop doesnt help 69 sw zero, -4(a0) # since we are limited by memory speed 70smallclr: 71 ble a1, zero, 2f 72 addu a3, a1, a0 # compute ending address 731: 74 addu a0, a0, 1 # clear bytes 75 bne a0, a3, 1b 76 sb zero, -1(a0) 772: 78 j ra 79 nop 80END(bzero) 81