1/* $OpenBSD: bzero.S,v 1.3 2003/06/02 23:28:09 millert Exp $ */ 2/* $NetBSD: bzero.S,v 1.1.1.1 1998/06/20 05:18:14 eeh Exp $ */ 3 4/* 5 * Copyright (c) 1992, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This software was developed by the Computer Systems Engineering group 9 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 10 * contributed to Berkeley. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. 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 * Header: bzero.s,v 1.1 92/06/25 12:52:46 torek Exp 37 */ 38 39#if defined(LIBC_SCCS) && !defined(lint) 40#ifdef notdef 41 .asciz "@(#)bzero.s 8.1 (Berkeley) 6/4/93" 42#endif 43 .asciz "$NetBSD: bzero.S,v 1.1.1.1 1998/06/20 05:18:14 eeh Exp $" 44#endif /* LIBC_SCCS and not lint */ 45 46#include "DEFS.h" 47 48/* 49 * bzero(addr, len) 50 * 51 * We should unroll the loop, but at the moment this would 52 * gain nothing since the `std' instructions are what limits us. 53 * 54 * I just changed all the `std's to `stx's. It still needs proper 55 * optimization using the block load/store ASIs. 56 */ 57ENTRY(bzero) 58#ifdef NOT_DEBUG 59 save %sp, -176, %sp 60 mov %i0, %o1 61 set 9f, %o0 62 call prom_printf 63 mov %i1, %o2 64 ba 8f 65 restore 669: .asciz "bzero(%p,%x)\r\n" 67 .align 4 688: 69#endif 70 ! %o0 = addr, %o1 = len 71 72 ! Optimize a common case: addr and len are both multiples of 8. 73 or %o0, %o1, %o2 74 andcc %o2, 7, %g0 ! ((addr | len) & 7) != 0? 75 bnz 1f ! if so, cannot optimize 76 clr %g1 ! in any case, we want g1=0 77 78 /* `Good' operands, can just store doubles. */ 790: 80 deccc 8, %o1 ! while ((len -= 8) >= 0) 81 bge,a 0b 82 stx %g0, [%o0 + %o1] ! *(quad *)(addr + len) = 0; 83 retl 84 nop 85 86 /* 87 * Either the address is unaligned, or the count is not a 88 * multiple of 8, or both. We will have to align the address 89 * in order to use anything `better' than stb. 90 */ 911: 92 cmp %o1, 15 ! len >= 15? 93 bge,a Lstd ! yes, use std 94 andcc %o0, 1, %g0 ! (but first check alignment) 95 96 ! not enough to bother: do byte-at-a-time loop. 972: 98 deccc %o1 ! while (--len >= 0) 99 bge,a 2b 100 stb %g0, [%o0 + %o1] ! addr[len] = 0; 101 retl 102 nop 103 104Lstd: 105 /* 106 * There are at least 15 bytes to zero. 107 * We may have to zero some initial stuff to align 108 * the address. 109 */ 110 bz,a 1f ! if (addr & 1) { 111 andcc %o0, 2, %g0 112 stb %g0, [%o0] ! *addr = 0; 113 inc %o0 ! addr++; 114 dec %o1 ! len--; 115 andcc %o0, 2, %g0 ! } 1161: 117 bz,a 1f ! if (addr & 2) { 118 andcc %o0, 4, %g0 119 sth %g0, [%o0] ! *(short *)addr = 0; 120 inc 2, %o0 ! addr += 2; 121 dec 2, %o1 ! len -= 2; 122 andcc %o0, 4, %g0 ! } 1231: 124 bz 1f ! if (addr & 4) { 125 dec 8, %o1 126 st %g0, [%o0] ! *(int *)addr = 0; 127 inc 4, %o0 ! addr += 4; 128 dec 4, %o1 ! len -= 4; 129 ! } 130 /* 131 * Address is double word aligned; len is 8 less than 132 * the number of bytes remaining (i.e., len is 0 if 133 * the remaining count is 8, 1 if it is 9, etc.). 134 */ 1351: 136 stx %g0, [%o0] ! do { 1372: ! *(quad *)addr = 0; 138 inc 8, %o0 ! addr += 8; 139 deccc 8, %o1 ! } while ((len -= 8) >= 0); 140 bge,a 2b 141 stx %g0, [%o0] 142 143 /* 144 * Len is in [-8..-1] where -8 => done, -7 => 1 byte to zero, 145 * -6 => two bytes, etc. Mop up this remainder, if any. 146 */ 147 andcc %o1, 4, %g0 148 bz 1f ! if (len & 4) { 149 andcc %o1, 2, %g0 150 st %g0, [%o0] ! *(int *)addr = 0; 151 inc 4, %o0 ! addr += 4; 1521: 153 bz 1f ! if (len & 2) { 154 andcc %o1, 1, %g0 155 sth %g0, [%o0] ! *(short *)addr = 0; 156 inc 2, %o0 ! addr += 2; 1571: 158 bnz,a 1f ! if (len & 1) 159 stb %g0, [%o0] ! *addr = 0; 1601: 161 retl 162 nop 163