1/*        $NetBSD: memcmp.S,v 1.5 2013/09/07 19:06:29 chs Exp $       */
2
3/*-
4 * Copyright (c) 1990 The Regents of the University of California.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * the Systems Programming Group of the University of Utah Computer
9 * Science Department.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#include <machine/asm.h>
37
38#if defined(LIBC_SCCS) && !defined(lint)
39#if 0
40          RCSID("from: @(#)bcmp.s       5.1 (Berkeley) 5/12/90")
41#else
42          RCSID("$NetBSD: memcmp.S,v 1.5 2013/09/07 19:06:29 chs Exp $")
43#endif
44#endif /* LIBC_SCCS and not lint */
45
46/* memcmp(s1, s2, n) */
47
48#ifdef __mcoldfire__
49#define   CMPMB(a,b)          movb b,%d2; cmpb a,%d2
50#define   CMPMW(a,b)          movw b,%d2; cmpw a,%d2
51#define   CMPML(a,b)          movl b,%d2; cmpl a,%d2
52#else
53#define   CMPMB(a,b)          cmpmb a,b
54#define   CMPMW(a,b)          cmpmw a,b
55#define   CMPML(a,b)          cmpml a,b
56#endif
57
58/*
59 * This is probably not the best we can do, but it is still 2-10 times
60 * faster than the C version in the portable gen directory.
61 *
62 * Things that might help:
63 *        - longword align when possible (only on the 68020)
64 *        - use nested DBcc instructions or use one and limit size to 64K
65 */
66ENTRY(memcmp)
67          movl      4(%sp),%a0                    | string 1
68          movl      8(%sp),%a1                    | string 2
69          movl      12(%sp),%d0                   | length
70#ifdef __mcoldfire__
71          movl      %d2,-(%sp)                    | save temp
72#endif
73          jeq       .Lbcdone            | if zero, nothing to do
74          movl      %a0,%d1
75          btst      #0,%d1                        | string 1 address odd?
76          jeq       .Lbceven            | no, skip alignment
77          CMPMB((%a0)+,(%a1)+)                    | yes, compare a byte
78          jne       .Lbcnoteq           | not equal, return non-zero
79          subql     #1,%d0                        | adjust count
80          jeq       .Lbcdone            | count 0, reutrn zero
81.Lbceven:
82          movl      %a1,%d1
83          btst      #0,%d1                        | string 2 address odd?
84          jne       .Lbcbloop           | yes, no hope for alignment, compare bytes
85          movl      %d0,%d1                       | no, both even
86          lsrl      #2,%d1                        | convert count to longword count
87          jeq       .Lbcbloop           | count 0, skip longword loop
88.Lbclloop:
89          CMPML((%a0)+,(%a1)+)                    | compare a longword
90          jne       .Lbcnoteql                    | not equal, return non-zero
91          subql     #1,%d1                        | adjust count
92          jne       .Lbclloop           | still more, keep comparing
93          andl      #3,%d0                        | what remains
94          jeq       .Lbcdone            | nothing, all done
95.Lbcbloop:
96          CMPMB((%a0)+,(%a1)+)                    | compare a byte
97          jne       .Lbcnoteq           | not equal, return non-zero
98          subql     #1,%d0                        | adjust count
99          jne       .Lbcbloop           | still more, keep going
100          rts
101.Lbcnoteql:
102          subql     #4,%a0
103          subql     #4,%a1
104          movl      #4,%d0
105          jra       .Lbcbloop
106.Lbcnoteq:
107          clrl      %d0
108          clrl      %d1
109          movb      -(%a0),%d0
110          movb      -(%a1),%d1
111          subl      %d1,%d0
112.Lbcdone:
113#ifdef __mcoldfire__
114          movl      (%sp)+,%sp                    | restore temp
115#endif
116          rts
117END(memcmp)
118