1/*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Ralph Campbell. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37#include <machine/machAsmDefs.h> 38 39#if defined(LIBC_SCCS) && !defined(lint) 40 ASMSTR("from: @(#)bzero.s 8.1 (Berkeley) 6/4/93") 41 ASMSTR("$Id: bzero.S,v 1.1 1994/05/24 07:12:50 glass Exp $") 42#endif /* LIBC_SCCS and not lint */ 43 44/* bzero(s1, n) */ 45 46LEAF(bzero) 47 .set noreorder 48 blt a1, 12, smallclr # small amount to clear? 49 subu a3, zero, a0 # compute # bytes to word align address 50 and a3, a3, 3 51 beq a3, zero, 1f # skip if word aligned 52 subu a1, a1, a3 # subtract from remaining count 53 swr zero, 0(a0) # clear 1, 2, or 3 bytes to align 54 addu a0, a0, a3 551: 56 and v0, a1, 3 # compute number of words left 57 subu a3, a1, v0 58 move a1, v0 59 addu a3, a3, a0 # compute ending address 602: 61 addu a0, a0, 4 # clear words 62 bne a0, a3, 2b # unrolling loop doesnt help 63 sw zero, -4(a0) # since we are limited by memory speed 64smallclr: 65 ble a1, zero, 2f 66 addu a3, a1, a0 # compute ending address 671: 68 addu a0, a0, 1 # clear bytes 69 bne a0, a3, 1b 70 sb zero, -1(a0) 712: 72 j ra 73 nop 74END(bzero) 75