Annotation of sys/lib/libkern/arch/mips64/bcopy.S, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: bcopy.S,v 1.4 2004/10/08 14:42:09 pefo Exp $ */
! 2: /*-
! 3: * Copyright (c) 1991, 1993
! 4: * The Regents of the University of California. All rights reserved.
! 5: *
! 6: * This code is derived from software contributed to Berkeley by
! 7: * Ralph Campbell.
! 8: *
! 9: * Redistribution and use in source and binary forms, with or without
! 10: * modification, are permitted provided that the following conditions
! 11: * are met:
! 12: * 1. Redistributions of source code must retain the above copyright
! 13: * notice, this list of conditions and the following disclaimer.
! 14: * 2. Redistributions in binary form must reproduce the above copyright
! 15: * notice, this list of conditions and the following disclaimer in the
! 16: * documentation and/or other materials provided with the distribution.
! 17: * 3. Neither the name of the University nor the names of its contributors
! 18: * may be used to endorse or promote products derived from this software
! 19: * without specific prior written permission.
! 20: *
! 21: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 22: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 23: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 24: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 25: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 26: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 27: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 28: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 29: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 30: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 31: * SUCH DAMAGE.
! 32: */
! 33:
! 34: #include "DEFS.h"
! 35:
! 36:
! 37: /*
! 38: * memcpy(to, from, len)
! 39: * {ov}bcopy(from, to, len)
! 40: */
! 41: LEAF(memcpy, 0)
! 42: .set noreorder
! 43: move v0, a0 # swap from and to
! 44: move a0, a1
! 45: move a1, v0
! 46: ALEAF(bcopy)
! 47: ALEAF(ovbcopy)
! 48: .set noreorder
! 49: PTR_ADDU t0, a0, a2 # t0 = end of s1 region
! 50: sltu t1, a1, t0
! 51: sltu t2, a0, a1
! 52: and t1, t1, t2 # t1 = true if from < to < (from+len)
! 53: beq t1, zero, forward # non overlapping, do forward copy
! 54: slt t2, a2, 12 # check for small copy
! 55:
! 56: ble a2, zero, 2f
! 57: PTR_ADDU t1, a1, a2 # t1 = end of to region
! 58: 1:
! 59: lb v1, -1(t0) # copy bytes backwards,
! 60: PTR_SUBU t0, t0, 1 # doesnt happen often so do slow way
! 61: PTR_SUBU t1, t1, 1
! 62: bne t0, a0, 1b
! 63: sb v1, 0(t1)
! 64: 2:
! 65: j ra
! 66: nop
! 67: forward:
! 68: bne t2, zero, smallcpy # do a small bcopy
! 69: xor v1, a0, a1 # compare low two bits of addresses
! 70: and v1, v1, 3
! 71: PTR_SUBU a3, zero, a1 # compute # bytes to word align address
! 72: beq v1, zero, aligned # addresses can be word aligned
! 73: and a3, a3, 3
! 74:
! 75: beq a3, zero, 1f
! 76: PTR_SUBU a2, a2, a3 # subtract from remaining count
! 77: LWHI v1, 0(a0) # get next 4 bytes (unaligned)
! 78: LWLO v1, 3(a0)
! 79: PTR_ADDU a0, a0, a3
! 80: SWHI v1, 0(a1) # store 1, 2, or 3 bytes to align a1
! 81: PTR_ADDU a1, a1, a3
! 82: 1:
! 83: and v1, a2, 3 # compute number of words left
! 84: PTR_SUBU a3, a2, v1
! 85: move a2, v1
! 86: PTR_ADDU a3, a3, a0 # compute ending address
! 87: 2:
! 88: LWHI v1, 0(a0) # copy words a0 unaligned, a1 aligned
! 89: LWLO v1, 3(a0)
! 90: PTR_ADDU a0, a0, 4
! 91: sw v1, 0(a1)
! 92: PTR_ADDU a1, a1, 4
! 93: bne a0, a3, 2b
! 94: nop # We have to do this mmu-bug.
! 95: b smallcpy
! 96: nop
! 97: aligned:
! 98: beq a3, zero, 1f
! 99: PTR_SUBU a2, a2, a3 # subtract from remaining count
! 100: LWHI v1, 0(a0) # copy 1, 2, or 3 bytes to align
! 101: PTR_ADDU a0, a0, a3
! 102: SWHI v1, 0(a1)
! 103: PTR_ADDU a1, a1, a3
! 104: 1:
! 105: and v1, a2, 3 # compute number of whole words left
! 106: PTR_SUBU a3, a2, v1
! 107: move a2, v1
! 108: PTR_ADDU a3, a3, a0 # compute ending address
! 109: 2:
! 110: lw v1, 0(a0) # copy words
! 111: PTR_ADDU a0, a0, 4
! 112: sw v1, 0(a1)
! 113: bne a0, a3, 2b
! 114: PTR_ADDU a1, a1, 4
! 115: smallcpy:
! 116: ble a2, zero, 2f
! 117: PTR_ADDU a3, a2, a0 # compute ending address
! 118: 1:
! 119: lbu v1, 0(a0) # copy bytes
! 120: PTR_ADDU a0, a0, 1
! 121: sb v1, 0(a1)
! 122: bne a0, a3, 1b
! 123: PTR_ADDU a1, a1, 1 # MMU BUG ? can not do -1(a1) at 0x80000000!!
! 124: 2:
! 125: j ra
! 126: nop
! 127: END(memcpy)
CVSweb