/* $NetBSD: bzero.S,v 1.1.1.1 1998/06/20 05:18:14 eeh 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. 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. * * Header: bzero.s,v 1.1 92/06/25 12:52:46 torek Exp */ #if defined(LIBC_SCCS) && !defined(lint) #ifdef notdef .asciz "@(#)bzero.s 8.1 (Berkeley) 6/4/93" #endif .asciz "$NetBSD: bzero.S,v 1.1.1.1 1998/06/20 05:18:14 eeh Exp $" #endif /* LIBC_SCCS and not lint */ #include "DEFS.h" /* * bzero(addr, len) * * We should unroll the loop, but at the moment this would * gain nothing since the `std' instructions are what limits us. * * I just changed all the `std's to `stx's. It still needs proper * optimization using the block load/store ASIs. */ ENTRY(bzero) #ifdef NOT_DEBUG save %sp, -176, %sp mov %i0, %o1 set 9f, %o0 call prom_printf mov %i1, %o2 ba 8f restore 9: .asciz "bzero(%p,%x)\r\n" .align 4 8: #endif ! %o0 = addr, %o1 = len ! Optimize a common case: addr and len are both multiples of 8. or %o0, %o1, %o2 andcc %o2, 7, %g0 ! ((addr | len) & 7) != 0? bnz 1f ! if so, cannot optimize clr %g1 ! in any case, we want g1=0 /* `Good' operands, can just store doubles. */ 0: deccc 8, %o1 ! while ((len -= 8) >= 0) bge,a 0b stx %g0, [%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 andcc %o0, 1, %g0 ! (but first check alignment) ! not enough to bother: do byte-at-a-time loop. 2: deccc %o1 ! while (--len >= 0) bge,a 2b stb %g0, [%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) { andcc %o0, 2, %g0 stb %g0, [%o0] ! *addr = 0; inc %o0 ! addr++; dec %o1 ! len--; andcc %o0, 2, %g0 ! } 1: bz,a 1f ! if (addr & 2) { andcc %o0, 4, %g0 sth %g0, [%o0] ! *(short *)addr = 0; inc 2, %o0 ! addr += 2; dec 2, %o1 ! len -= 2; andcc %o0, 4, %g0 ! } 1: bz 1f ! if (addr & 4) { dec 8, %o1 st %g0, [%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: stx %g0, [%o0] ! do { 2: ! *(quad *)addr = 0; inc 8, %o0 ! addr += 8; deccc 8, %o1 ! } while ((len -= 8) >= 0); bge,a 2b stx %g0, [%o0] /* * Len is in [-8..-1] where -8 => done, -7 => 1 byte to zero, * -6 => two bytes, etc. Mop up this remainder, if any. */ andcc %o1, 4, %g0 bz 1f ! if (len & 4) { andcc %o1, 2, %g0 st %g0, [%o0] ! *(int *)addr = 0; inc 4, %o0 ! addr += 4; 1: bz 1f ! if (len & 2) { andcc %o1, 1, %g0 sth %g0, [%o0] ! *(short *)addr = 0; inc 2, %o0 ! addr += 2; 1: bnz,a 1f ! if (len & 1) stb %g0, [%o0] ! *addr = 0; 1: retl nop