bzero.S revision 1.5
1 1.5 jonathan /* $NetBSD: bzero.S,v 1.5 1996/09/17 01:32:33 jonathan Exp $ */ 2 1.4 jonathan 3 1.1 glass /*- 4 1.1 glass * Copyright (c) 1991, 1993 5 1.1 glass * The Regents of the University of California. All rights reserved. 6 1.1 glass * 7 1.1 glass * This code is derived from software contributed to Berkeley by 8 1.1 glass * Ralph Campbell. 9 1.1 glass * 10 1.1 glass * Redistribution and use in source and binary forms, with or without 11 1.1 glass * modification, are permitted provided that the following conditions 12 1.1 glass * are met: 13 1.1 glass * 1. Redistributions of source code must retain the above copyright 14 1.1 glass * notice, this list of conditions and the following disclaimer. 15 1.1 glass * 2. Redistributions in binary form must reproduce the above copyright 16 1.1 glass * notice, this list of conditions and the following disclaimer in the 17 1.1 glass * documentation and/or other materials provided with the distribution. 18 1.1 glass * 3. All advertising materials mentioning features or use of this software 19 1.1 glass * must display the following acknowledgement: 20 1.1 glass * This product includes software developed by the University of 21 1.1 glass * California, Berkeley and its contributors. 22 1.1 glass * 4. Neither the name of the University nor the names of its contributors 23 1.1 glass * may be used to endorse or promote products derived from this software 24 1.1 glass * without specific prior written permission. 25 1.1 glass * 26 1.1 glass * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 1.1 glass * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 1.1 glass * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 1.1 glass * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 1.1 glass * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 1.1 glass * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 1.1 glass * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 1.1 glass * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 1.1 glass * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 1.1 glass * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 1.1 glass * SUCH DAMAGE. 37 1.1 glass */ 38 1.1 glass 39 1.5 jonathan #include <mips/asm.h> 40 1.1 glass 41 1.1 glass #if defined(LIBC_SCCS) && !defined(lint) 42 1.1 glass ASMSTR("from: @(#)bzero.s 8.1 (Berkeley) 6/4/93") 43 1.5 jonathan ASMSTR("$NetBSD: bzero.S,v 1.5 1996/09/17 01:32:33 jonathan Exp $") 44 1.1 glass #endif /* LIBC_SCCS and not lint */ 45 1.5 jonathan 46 1.5 jonathan #ifdef ABICALLS 47 1.5 jonathan .abicalls 48 1.5 jonathan #endif 49 1.1 glass 50 1.1 glass /* bzero(s1, n) */ 51 1.1 glass 52 1.3 mycroft LEAF(bzero) 53 1.1 glass .set noreorder 54 1.1 glass blt a1, 12, smallclr # small amount to clear? 55 1.1 glass subu a3, zero, a0 # compute # bytes to word align address 56 1.1 glass and a3, a3, 3 57 1.1 glass beq a3, zero, 1f # skip if word aligned 58 1.1 glass subu a1, a1, a3 # subtract from remaining count 59 1.1 glass swr zero, 0(a0) # clear 1, 2, or 3 bytes to align 60 1.1 glass addu a0, a0, a3 61 1.1 glass 1: 62 1.1 glass and v0, a1, 3 # compute number of words left 63 1.1 glass subu a3, a1, v0 64 1.1 glass move a1, v0 65 1.1 glass addu a3, a3, a0 # compute ending address 66 1.1 glass 2: 67 1.1 glass addu a0, a0, 4 # clear words 68 1.1 glass bne a0, a3, 2b # unrolling loop doesnt help 69 1.1 glass sw zero, -4(a0) # since we are limited by memory speed 70 1.1 glass smallclr: 71 1.1 glass ble a1, zero, 2f 72 1.1 glass addu a3, a1, a0 # compute ending address 73 1.1 glass 1: 74 1.1 glass addu a0, a0, 1 # clear bytes 75 1.1 glass bne a0, a3, 1b 76 1.1 glass sb zero, -1(a0) 77 1.1 glass 2: 78 1.1 glass j ra 79 1.1 glass nop 80 1.3 mycroft END(bzero) 81
Indexes created Mon Sep 22 21:09:42 GMT 2025