1/* $NetBSD: bzero.S,v 1.7 2002/11/10 18:10:26 thorpej 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 1.7 2002/11/10 18:10:26 thorpej Exp $") 44#endif /* LIBC_SCCS and not lint */ 45 46 47#define _LOCORE /* XXX not really, just assembly-code source */ 48#include <machine/endian.h> 49 50#ifdef __ABICALLS__ 51 .abicalls 52#endif 53 54/* bzero(s1, n) */ 55 56LEAF(bzero) 57 .set noreorder 58 blt a1, 12, smallclr # small amount to clear? 59 subu a3, zero, a0 # compute # bytes to word align address 60 and a3, a3, 3 61 beq a3, zero, 1f # skip if word aligned 62 subu a1, a1, a3 # subtract from remaining count 63 SWHI zero, 0(a0) # clear 1, 2, or 3 bytes to align 64 addu a0, a0, a3 651: 66 and v0, a1, 3 # compute number of words left 67 subu a3, a1, v0 68 move a1, v0 69 addu a3, a3, a0 # compute ending address 702: 71 addu a0, a0, 4 # clear words 72 bne a0, a3, 2b # unrolling loop doesnt help 73 sw zero, -4(a0) # since we are limited by memory speed 74smallclr: 75 ble a1, zero, 2f 76 addu a3, a1, a0 # compute ending address 771: 78 addu a0, a0, 1 # clear bytes 79 bne a0, a3, 1b 80 sb zero, -1(a0) 812: 82 j ra 83 nop 84END(bzero) 85