bzero.S revision 1.9
1 1.9 matt /* $NetBSD: bzero.S,v 1.9 2009/12/14 01:07:42 matt 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 1.8 agc * 3. Neither the name of the University nor the names of its contributors 19 1.1 glass * may be used to endorse or promote products derived from this software 20 1.1 glass * without specific prior written permission. 21 1.1 glass * 22 1.1 glass * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 1.1 glass * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 1.1 glass * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 1.1 glass * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 1.1 glass * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 1.1 glass * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 1.1 glass * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 1.1 glass * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 1.1 glass * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 1.1 glass * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 1.1 glass * SUCH DAMAGE. 33 1.1 glass */ 34 1.1 glass 35 1.5 jonathan #include <mips/asm.h> 36 1.1 glass 37 1.1 glass #if defined(LIBC_SCCS) && !defined(lint) 38 1.9 matt #if 0 39 1.9 matt RCSID("from: @(#)bzero.s 8.1 (Berkeley) 6/4/93") 40 1.9 matt #else 41 1.9 matt RCSID("$NetBSD: bzero.S,v 1.9 2009/12/14 01:07:42 matt Exp $") 42 1.9 matt #endif 43 1.1 glass #endif /* LIBC_SCCS and not lint */ 44 1.5 jonathan 45 1.6 jonathan 46 1.6 jonathan #define _LOCORE /* XXX not really, just assembly-code source */ 47 1.6 jonathan #include <machine/endian.h> 48 1.6 jonathan 49 1.1 glass /* bzero(s1, n) */ 50 1.1 glass 51 1.3 mycroft LEAF(bzero) 52 1.1 glass .set noreorder 53 1.9 matt blt a1, 3*SZREG, smallclr # small amount to clear? 54 1.9 matt PTR_SUBU a3, zero, a0 # compute # bytes to word align address 55 1.9 matt and a3, a3, SZREG-1 56 1.9 matt beq a3, zero, 1f # skip if word aligned 57 1.9 matt #if SZREG == 4 58 1.9 matt PTR_SUBU a1, a1, a3 # subtract from remaining count 59 1.9 matt SWHI zero, 0(a0) # clear 1, 2, or 3 bytes to align 60 1.9 matt PTR_ADDU a0, a0, a3 61 1.9 matt #endif 62 1.9 matt #if SZREG == 8 63 1.9 matt PTR_SUBU a1, a1, a3 # subtract from remaining count 64 1.9 matt PTR_ADDU a0, a0, a3 # align dst to next word 65 1.9 matt sll a3, a3, 3 # bits to bytes 66 1.9 matt li a2, -1 # make a mask 67 1.9 matt #if _BYTE_ORDER == _BIG_ENDIAN 68 1.9 matt REG_SRLV a2, a2, a3 # we want to keep the MSB bytes 69 1.9 matt #endif 70 1.9 matt #if _BYTE_ORDER == _LITTLE_ENDIAN 71 1.9 matt REG_SLLV a2, a2, a3 # we want to keep the LSB bytes 72 1.9 matt #endif 73 1.9 matt nor a2, zero, a2 # complement the mask 74 1.9 matt REL_L v0, -SZREG(a0) # load the word to partially clear 75 1.9 matt and v0, v0, a2 # clear the bytes 76 1.9 matt REG_S v0, -SZREG(a0) # store it back 77 1.9 matt #endif 78 1.1 glass 1: 79 1.9 matt and v0, a1, SZREG-1 # compute number of words left 80 1.9 matt PTR_SUBU a3, a1, v0 81 1.9 matt move a1, v0 82 1.9 matt PTR_ADDU a3, a3, a0 # compute ending address 83 1.1 glass 2: 84 1.9 matt PTR_ADDU a0, a0, SZREG # clear words 85 1.9 matt bne a0, a3, 2b # unrolling loop doesnt help 86 1.9 matt REG_S zero, -SZREG(a0) # since we are limited by memory speed 87 1.1 glass smallclr: 88 1.9 matt ble a1, zero, 2f 89 1.9 matt PTR_ADDU a3, a1, a0 # compute ending address 90 1.1 glass 1: 91 1.9 matt PTR_ADDU a0, a0, 1 # clear bytes 92 1.9 matt bne a0, a3, 1b 93 1.9 matt sb zero, -1(a0) 94 1.1 glass 2: 95 1.9 matt j ra 96 1.1 glass nop 97 1.3 mycroft END(bzero) 98
Indexes created Mon Sep 22 10:09:38 GMT 2025