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/*-
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Ralph Campbell.
*
* 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.
*/
#include <machine/asm.h>
#if defined(LIBC_SCCS)
.text
.asciz "$OpenBSD: bcopy.S,v 1.2 2004/09/09 16:14:02 pefo Exp $"
#endif /* LIBC_SCCS */
/* bcopy(s1, s2, n) */
LEAF(bcopy, 0)
.set noreorder
addu t0, a0, a2 # t0 = end of s1 region
sltu t1, a1, t0
sltu t2, a0, a1
and t1, t1, t2 # t1 = true if from < to < (from+len)
beq t1, zero, forward # non overlapping, do forward copy
slt t2, a2, 12 # check for small copy
ble a2, zero, 2f
addu t1, a1, a2 # t1 = end of to region
1:
lb v0, -1(t0) # copy bytes backwards,
subu t0, t0, 1 # does not happen often so do slow way
subu t1, t1, 1
bne t0, a0, 1b
sb v0, 0(t1)
2:
j ra
nop
forward:
bne t2, zero, smallcpy # do a small bcopy
xor v0, a0, a1 # compare low two bits of addresses
and v0, v0, 3
subu a3, zero, a1 # compute # bytes to word align address
beq v0, zero, aligned # addresses can be word aligned
and a3, a3, 3
beq a3, zero, 1f
subu a2, a2, a3 # subtract from remaining count
LWHI v0, 0(a0) # get next 4 bytes (unaligned)
LWLO v0, 3(a0)
addu a0, a0, a3
SWHI v0, 0(a1) # store 1, 2, or 3 bytes to align a1
addu a1, a1, a3
1:
and v0, a2, 3 # compute number of words left
subu a3, a2, v0
move a2, v0
addu a3, a3, a0 # compute ending address
2:
LWHI v0, 0(a0) # copy words a0 unaligned, a1 aligned
LWLO v0, 3(a0)
addu a0, a0, 4
addu a1, a1, 4
bne a0, a3, 2b
sw v0, -4(a1)
b smallcpy
nop
aligned:
beq a3, zero, 1f
subu a2, a2, a3 # subtract from remaining count
LWHI v0, 0(a0) # copy 1, 2, or 3 bytes to align
addu a0, a0, a3
SWHI v0, 0(a1)
addu a1, a1, a3
1:
and v0, a2, 3 # compute number of whole words left
subu a3, a2, v0
move a2, v0
addu a3, a3, a0 # compute ending address
2:
lw v0, 0(a0) # copy words
addu a0, a0, 4
addu a1, a1, 4
bne a0, a3, 2b
sw v0, -4(a1)
smallcpy:
ble a2, zero, 2f
addu a3, a2, a0 # compute ending address
1:
lbu v0, 0(a0) # copy bytes
addu a0, a0, 1
addu a1, a1, 1
bne a0, a3, 1b
sb v0, -1(a1)
2:
j ra
nop
.set reorder
END(bcopy)
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