/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* 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.
*/
/*
* This is probably not the best we can do, but it is still 2-10 times
* faster than the C version in the portable gen directory.
*
* Things that might help:
* - longword align when possible (only on the 68020)
* - use nested DBcc instructions or use one and limit size to 64K
*/
ENTRY(memcmp)
movl 4(%sp),%a0 | string 1
movl 8(%sp),%a1 | string 2
movl 12(%sp),%d0 | length
#ifdef __mcoldfire__
movl %d2,-(%sp) | save temp
#endif
jeq .Lbcdone | if zero, nothing to do
movl %a0,%d1
btst #0,%d1 | string 1 address odd?
jeq .Lbceven | no, skip alignment
CMPMB((%a0)+,(%a1)+) | yes, compare a byte
jne .Lbcnoteq | not equal, return non-zero
subql #1,%d0 | adjust count
jeq .Lbcdone | count 0, reutrn zero
Lbceven:
movl %a1,%d1
btst #0,%d1 | string 2 address odd?
jne .Lbcbloop | yes, no hope for alignment, compare bytes
movl %d0,%d1 | no, both even
lsrl #2,%d1 | convert count to longword count
jeq .Lbcbloop | count 0, skip longword loop
Lbclloop:
CMPML((%a0)+,(%a1)+) | compare a longword
jne .Lbcnoteql | not equal, return non-zero
subql #1,%d1 | adjust count
jne .Lbclloop | still more, keep comparing
andl #3,%d0 | what remains
jeq .Lbcdone | nothing, all done
Lbcbloop:
CMPMB((%a0)+,(%a1)+) | compare a byte
jne .Lbcnoteq | not equal, return non-zero
subql #1,%d0 | adjust count
jne .Lbcbloop | still more, keep going
rts
Lbcnoteql:
subql #4,%a0
subql #4,%a1
movl #4,%d0
jra .Lbcbloop
Lbcnoteq:
clrl %d0
clrl %d1
movb -(%a0),%d0
movb -(%a1),%d1
subl %d1,%d0
Lbcdone:
#ifdef __mcoldfire__
movl (%sp)+,%sp | restore temp
#endif
rts
END(memcmp)
