Annotation of sys/lib/libkern/arch/sparc64/bzero.S, Revision 1.1
1.1 ! nbrk 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: */
! 57: ENTRY(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
! 66: 9: .asciz "bzero(%p,%x)\r\n"
! 67: .align 4
! 68: 8:
! 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. */
! 79: 0:
! 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: */
! 91: 1:
! 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.
! 97: 2:
! 98: deccc %o1 ! while (--len >= 0)
! 99: bge,a 2b
! 100: stb %g0, [%o0 + %o1] ! addr[len] = 0;
! 101: retl
! 102: nop
! 103:
! 104: Lstd:
! 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 ! }
! 116: 1:
! 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 ! }
! 123: 1:
! 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: */
! 135: 1:
! 136: stx %g0, [%o0] ! do {
! 137: 2: ! *(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;
! 152: 1:
! 153: bz 1f ! if (len & 2) {
! 154: andcc %o1, 1, %g0
! 155: sth %g0, [%o0] ! *(short *)addr = 0;
! 156: inc 2, %o0 ! addr += 2;
! 157: 1:
! 158: bnz,a 1f ! if (len & 1)
! 159: stb %g0, [%o0] ! *addr = 0;
! 160: 1:
! 161: retl
! 162: nop
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