1 /* $NetBSD: bzero.S,v 1.10 2009/12/14 02:53:52 matt 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 <mips/asm.h> 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 #if 0 39 RCSID("from: @(#)bzero.s 8.1 (Berkeley) 6/4/93") 40 #else 41 RCSID("$NetBSD: bzero.S,v 1.10 2009/12/14 02:53:52 matt Exp $") 42 #endif 43 #endif /* LIBC_SCCS and not lint */ 44 45 46 #define _LOCORE /* XXX not really, just assembly-code source */ 47 #include <machine/endian.h> 48 49 /* bzero(s1, n) */ 50 51 LEAF(bzero) 52 .set noreorder 53 blt a1, 3*SZREG, smallclr # small amount to clear? 54 PTR_SUBU a3, zero, a0 # compute # bytes to word align address 55 and a3, a3, SZREG-1 56 beq a3, zero, 1f # skip if word aligned 57 #if SZREG == 4 58 PTR_SUBU a1, a1, a3 # subtract from remaining count 59 SWHI zero, 0(a0) # clear 1, 2, or 3 bytes to align 60 PTR_ADDU a0, a0, a3 61 #endif 62 #if SZREG == 8 63 PTR_SUBU a1, a1, a3 # subtract from remaining count 64 PTR_ADDU a0, a0, a3 # align dst to next word 65 sll a3, a3, 3 # bits to bytes 66 li a2, -1 # make a mask 67 #if _BYTE_ORDER == _BIG_ENDIAN 68 REG_SRLV a2, a2, a3 # we want to keep the MSB bytes 69 #endif 70 #if _BYTE_ORDER == _LITTLE_ENDIAN 71 REG_SLLV a2, a2, a3 # we want to keep the LSB bytes 72 #endif 73 nor a2, zero, a2 # complement the mask 74 REG_L v0, -SZREG(a0) # load the word to partially clear 75 and v0, v0, a2 # clear the bytes 76 REG_S v0, -SZREG(a0) # store it back 77 #endif 78 1: 79 and v0, a1, SZREG-1 # compute number of words left 80 PTR_SUBU a3, a1, v0 81 move a1, v0 82 PTR_ADDU a3, a3, a0 # compute ending address 83 2: 84 PTR_ADDU a0, a0, SZREG # clear words 85 bne a0, a3, 2b # unrolling loop doesnt help 86 REG_S zero, -SZREG(a0) # since we are limited by memory speed 87 smallclr: 88 ble a1, zero, 2f 89 PTR_ADDU a3, a1, a0 # compute ending address 90 1: 91 PTR_ADDU a0, a0, 1 # clear bytes 92 bne a0, a3, 1b 93 sb zero, -1(a0) 94 2: 95 j ra 96 nop 97 END(bzero) 98
Indexes created Sat Sep 20 22:09:52 GMT 2025