1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
|
/*-
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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 "$OpenBSD$"
#endif /* LIBC_SCCS */
/* 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
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
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)
addu a1, a1, a3
bne v0, v1, nomatch
addu a0, a0, a3
1:
and a3, a2, ~3 # compute number of whole words left
subu a2, a2, a3 # which has to be >= (16-3) & ~3
addu a3, a3, a0 # compute ending address
2:
lw v0, 0(a0) # compare words
lw v1, 0(a1)
addu a0, a0, 4
bne v0, v1, nomatch
addu a1, a1, 4
bne a0, a3, 2b
nop
b small # finish remainder
nop
unaligned:
beq a3, zero, 2f
subu a2, a2, a3 # subtract from remaining count
addu a3, a3, a0 # compute ending address
1:
lbu v0, 0(a0) # compare bytes until a1 word aligned
lbu v1, 0(a1)
addu a0, a0, 1
bne v0, v1, nomatch
addu a1, a1, 1
bne a0, a3, 1b
nop
2:
and a3, a2, ~3 # compute number of whole words left
subu a2, a2, a3 # which has to be >= (16-3) & ~3
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)
addu a0, a0, 4
bne v0, v1, nomatch
addu a1, a1, 4
bne a0, a3, 3b
nop
small:
ble a2, zero, match
addu a3, a2, a0 # compute ending address
1:
lbu v0, 0(a0)
lbu v1, 0(a1)
addu a0, a0, 1
bne v0, v1, nomatch
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)
|
