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/* $NetBSD: bcmp.S,v 1.9 2009/12/14 01:07:42 matt Exp $ */
/*-
* 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>
__FBSDID("$FreeBSD$");
#define _LOCORE /* XXX not really, just assembly-code source */
#include <machine/endian.h> /* LWLO/LWHI, SWLO/SWHI */
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
ASMSTR("from: @(#)bcmp.s 8.1 (Berkeley) 6/4/93")
#else
ASMSTR("$NetBSD: bcmp.S,v 1.9 2009/12/14 01:07:42 matt Exp $")
#endif
#endif /* LIBC_SCCS and not lint */
#ifdef __ABICALLS__
.abicalls
#endif
/* bcmp(s1, s2, n) */
LEAF(bcmp)
.set noreorder
blt a2, 16, small # is it worth any trouble?
xor v0, a0, a1 # compare low two bits of addresses
and v0, v0, 3
PTR_SUBU a3, zero, a1 # compute # bytes to word align address
bne v0, zero, unaligned # not possible to align addresses
and a3, a3, 3
beq a3, zero, 1f
PTR_SUBU a2, a2, a3 # subtract from remaining count
move v0, v1 # init v0,v1 so unmodified bytes match
LWHI v0, 0(a0) # read 1, 2, or 3 bytes
LWHI v1, 0(a1)
PTR_ADDU a1, a1, a3
bne v0, v1, nomatch
PTR_ADDU a0, a0, a3
1:
and a3, a2, ~3 # compute number of whole words left
PTR_SUBU a2, a2, a3 # which has to be >= (16-3) & ~3
PTR_ADDU a3, a3, a0 # compute ending address
2:
lw v0, 0(a0) # compare words
lw v1, 0(a1)
PTR_ADDU a0, a0, 4
bne v0, v1, nomatch
PTR_ADDU a1, a1, 4
bne a0, a3, 2b
nop
b small # finish remainder
nop
unaligned:
beq a3, zero, 2f
PTR_SUBU a2, a2, a3 # subtract from remaining count
PTR_ADDU a3, a3, a0 # compute ending address
1:
lbu v0, 0(a0) # compare bytes until a1 word aligned
lbu v1, 0(a1)
PTR_ADDU a0, a0, 1
bne v0, v1, nomatch
PTR_ADDU a1, a1, 1
bne a0, a3, 1b
nop
2:
and a3, a2, ~3 # compute number of whole words left
PTR_SUBU a2, a2, a3 # which has to be >= (16-3) & ~3
PTR_ADDU a3, a3, a0 # compute ending address
3:
LWHI v0, 0(a0) # compare words a0 unaligned, a1 aligned
LWLO v0, 3(a0)
lw v1, 0(a1)
PTR_ADDU a0, a0, 4
bne v0, v1, nomatch
PTR_ADDU a1, a1, 4
bne a0, a3, 3b
nop
small:
ble a2, zero, match
PTR_ADDU a3, a2, a0 # compute ending address
1:
lbu v0, 0(a0)
lbu v1, 0(a1)
PTR_ADDU a0, a0, 1
bne v0, v1, nomatch
PTR_ADDU a1, a1, 1
bne a0, a3, 1b
nop
match:
j ra
move v0, zero
nomatch:
j ra
li v0, 1
.set reorder
END(bcmp)
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