1/*        $NetBSD: bcmp.S,v 1.9 2009/12/14 01:07:42 matt Exp $        */
2
3/*-
4 * Copyright (c) 1991, 1993
5 *        The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Ralph Campbell.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <mips/asm.h>
36#define _LOCORE               /* XXX not really, just assembly-code source */
37#include <machine/endian.h>   /* LWLO/LWHI, SWLO/SWHI */
38
39#if defined(LIBC_SCCS) && !defined(lint)
40#if 0
41          RCSID("from: @(#)bcmp.s       8.1 (Berkeley) 6/4/93")
42#else
43          RCSID("$NetBSD: bcmp.S,v 1.9 2009/12/14 01:07:42 matt Exp $")
44#endif
45#endif /* LIBC_SCCS and not lint */
46
47/* bcmp(s1, s2, n) */
48
49
50LEAF(bcmp)
51          .set      noreorder
52          blt                 a2, 16, small       # is it worth any trouble?
53          xor                 v0, a0, a1          # compare low two bits of addresses
54          and                 v0, v0, 3
55          PTR_SUBU  a3, zero, a1        # compute # bytes to word align address
56          bne                 v0, zero, unaligned # not possible to align addresses
57          and                 a3, a3, 3
58
59          beq                 a3, zero, 1f
60          PTR_SUBU  a2, a2, a3          # subtract from remaining count
61          move                v0, v1              # init v0,v1 so unmodified bytes match
62          LWHI                v0, 0(a0) # read 1, 2, or 3 bytes
63          LWHI                v1, 0(a1)
64          PTR_ADDU  a1, a1, a3
65          bne                 v0, v1, nomatch
66          PTR_ADDU  a0, a0, a3
671:
68          and                 a3, a2, ~3          # compute number of whole words left
69          PTR_SUBU  a2, a2, a3          #   which has to be >= (16-3) & ~3
70          PTR_ADDU  a3, a3, a0          # compute ending address
712:
72          lw                  v0, 0(a0) # compare words
73          lw                  v1, 0(a1)
74          PTR_ADDU  a0, a0, 4
75          bne                 v0, v1, nomatch
76          PTR_ADDU  a1, a1, 4
77          bne                 a0, a3, 2b
78          nop
79          b                   small               # finish remainder
80          nop
81unaligned:
82          beq                 a3, zero, 2f
83          PTR_SUBU  a2, a2, a3          # subtract from remaining count
84          PTR_ADDU  a3, a3, a0          # compute ending address
851:
86          lbu                 v0, 0(a0) # compare bytes until a1 word aligned
87          lbu                 v1, 0(a1)
88          PTR_ADDU  a0, a0, 1
89          bne                 v0, v1, nomatch
90          PTR_ADDU  a1, a1, 1
91          bne                 a0, a3, 1b
92          nop
932:
94          and                 a3, a2, ~3          # compute number of whole words left
95          PTR_SUBU  a2, a2, a3          #   which has to be >= (16-3) & ~3
96          PTR_ADDU  a3, a3, a0          # compute ending address
973:
98          LWHI                v0, 0(a0) # compare words a0 unaligned, a1 aligned
99          LWLO                v0, 3(a0)
100          lw                  v1, 0(a1)
101          PTR_ADDU  a0, a0, 4
102          bne                 v0, v1, nomatch
103          PTR_ADDU  a1, a1, 4
104          bne                 a0, a3, 3b
105          nop
106small:
107          ble                 a2, zero, match
108          PTR_ADDU  a3, a2, a0                    # compute ending address
1091:
110          lbu                 v0, 0(a0)
111          lbu                 v1, 0(a1)
112          PTR_ADDU  a0, a0, 1
113          bne                 v0, v1, nomatch
114          PTR_ADDU  a1, a1, 1
115          bne                 a0, a3, 1b
116          nop
117match:
118          j                   ra
119          move                v0, zero
120nomatch:
121          j                   ra
122          li                  v0, 1
123          .set      reorder
124END(bcmp)
125