/* $NetBSD: bzero.S,v 1.1 2005/12/20 19:28:50 christos Exp $ */ /* * Copyright (c) 1992, 1993 * The Regents of the University of California. All rights reserved. * * This software was developed by the Computer Systems Engineering group * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and * contributed to Berkeley. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * from: Header: bzero.s,v 1.1 92/06/25 12:52:46 torek Exp */ #include <machine/asm.h> #if defined(LIBC_SCCS) && !defined(lint) #if 0 .asciz "@(#)bzero.s 8.1 (Berkeley) 6/4/93" #else RCSID("$NetBSD: bzero.S,v 1.1 2005/12/20 19:28:50 christos Exp $") #endif #endif /* LIBC_SCCS and not lint */ /* * We should unroll the loop, but at the moment this would * gain nothing since the `std' instructions are what limits us. */ #ifdef MEMSET /* * void * * memset(void *addr, int pattern, size_t len) */ ENTRY(memset) ! %o0 = addr, %o1 = pattern, %o2 = len /* * Expand the byte pattern to fill 64 bits in an even-aligned * register pair; shuffle arguments to match those of bzero. */ and %o1, 0xff, %o3 mov %o2, %o1 ! shuffle argument sll %o3, 8, %o2 or %o2, %o3, %o2 mov %o0, %g1 ! save original pointer sll %o2, 16, %o3 or %o2, %o3, %o2 ! Optimize a common case: addr and len are both multiples of 8. or %o0, %o1, %o5 btst 7, %o5 ! ((addr | len) & 7) != 0? bnz 1f ! if so, cannot optimize mov %o2, %o3 ! in any case, complete pat expansion #else /* * void * bzero(void *addr, size_t len) */ ENTRY(bzero) ! %o0 = addr, %o1 = len clr %o2 ! Optimize a common case: addr and len are both multiples of 8. or %o0, %o1, %o5 btst 7, %o5 ! ((addr | len) & 7) != 0? bnz 1f ! if so, cannot optimize clr %o3 ! in any case, we want o3=0 #endif /* `Good' operands, can just store doubles. */ 0: deccc 8, %o1 ! while ((len -= 8) >= 0) bge,a 0b std %o2, [%o0 + %o1] ! *(quad *)(addr + len) = 0; retl nop /* * Either the address is unaligned, or the count is not a * multiple of 8, or both. We will have to align the address * in order to use anything `better' than stb. */ 1: cmp %o1, 15 ! len >= 15? bge,a Lstd ! yes, use std btst 1, %o0 ! (but first check alignment) ! not enough to bother: do byte-at-a-time loop. 2: deccc %o1 ! while (--len >= 0) bge,a 2b stb %o2, [%o0 + %o1] ! addr[len] = 0; retl nop Lstd: /* * There are at least 15 bytes to zero. * We may have to zero some initial stuff to align * the address. */ bz,a 1f ! if (addr & 1) { btst 2, %o0 stb %o2, [%o0] ! *addr = 0; inc %o0 ! addr++; dec %o1 ! len--; btst 2, %o0 ! } 1: bz,a 1f ! if (addr & 2) { btst 4, %o0 sth %o2, [%o0] ! *(short *)addr = 0; inc 2, %o0 ! addr += 2; dec 2, %o1 ! len -= 2; btst 4, %o0 ! } 1: bz 1f ! if (addr & 4) { dec 8, %o1 st %o2, [%o0] ! *(int *)addr = 0; inc 4, %o0 ! addr += 4; dec 4, %o1 ! len -= 4; ! } /* * Address is double word aligned; len is 8 less than * the number of bytes remaining (i.e., len is 0 if * the remaining count is 8, 1 if it is 9, etc.). */ 1: std %o2, [%o0] ! do { 2: ! *(quad *)addr = 0; inc 8, %o0 ! addr += 8; deccc 8, %o1 ! } while ((len -= 8) >= 0); bge,a 2b std %o2, [%o0] /* * Len is in [-8..-1] where -8 => done, -7 => 1 byte to zero, * -6 => two bytes, etc. Mop up this remainder, if any. */ btst 4, %o1 bz 1f ! if (len & 4) { btst 2, %o1 st %o2, [%o0] ! *(int *)addr = 0; inc 4, %o0 ! addr += 4; 1: bz 1f ! if (len & 2) { btst 1, %o1 sth %o2, [%o0] ! *(short *)addr = 0; inc 2, %o0 ! addr += 2; 1: bnz,a 1f ! if (len & 1) stb %o2, [%o0] ! *addr = 0; 1: retl #ifdef MEMSET mov %g1, %o0 ! restore original pointer #else nop #endif
