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Linux kernel mirror (for testing)
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1/*
2 * File: arch/blackfin/lib/memcmp.S
3 * Based on:
4 * Author:
5 *
6 * Created:
7 * Description:
8 *
9 * Modified:
10 * Copyright 2004-2006 Analog Devices Inc.
11 *
12 * Bugs: Enter bugs at http://blackfin.uclinux.org/
13 *
14 * This program is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2 of the License, or
17 * (at your option) any later version.
18 *
19 * This program is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
23 *
24 * You should have received a copy of the GNU General Public License
25 * along with this program; if not, see the file COPYING, or write
26 * to the Free Software Foundation, Inc.,
27 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
28 */
29
30#include <linux/linkage.h>
31
32/* int memcmp(const void *s1, const void *s2, size_t n);
33 * R0 = First Address (s1)
34 * R1 = Second Address (s2)
35 * R2 = count (n)
36 *
37 * Favours word aligned data.
38 */
39
40.text
41
42.align 2
43
44ENTRY(_memcmp)
45 I1 = P3;
46 P0 = R0; /* P0 = s1 address */
47 P3 = R1; /* P3 = s2 Address */
48 P2 = R2 ; /* P2 = count */
49 CC = R2 <= 7(IU);
50 IF CC JUMP .Ltoo_small;
51 I0 = R1; /* s2 */
52 R1 = R1 | R0; /* OR addresses together */
53 R1 <<= 30; /* check bottom two bits */
54 CC = AZ; /* AZ set if zero. */
55 IF !CC JUMP .Lbytes ; /* Jump if addrs not aligned. */
56
57 P1 = P2 >> 2; /* count = n/4 */
58 R3 = 3;
59 R2 = R2 & R3; /* remainder */
60 P2 = R2; /* set remainder */
61
62 LSETUP (.Lquad_loop_s, .Lquad_loop_e) LC0=P1;
63.Lquad_loop_s:
64 MNOP || R0 = [P0++] || R1 = [I0++];
65 CC = R0 == R1;
66 IF !CC JUMP .Lquad_different;
67.Lquad_loop_e:
68 NOP;
69
70 P3 = I0; /* s2 */
71.Ltoo_small:
72 CC = P2 == 0; /* Check zero count*/
73 IF CC JUMP .Lfinished; /* very unlikely*/
74
75.Lbytes:
76 LSETUP (.Lbyte_loop_s, .Lbyte_loop_e) LC0=P2;
77.Lbyte_loop_s:
78 R1 = B[P3++](Z); /* *s2 */
79 R0 = B[P0++](Z); /* *s1 */
80 CC = R0 == R1;
81 IF !CC JUMP .Ldifferent;
82.Lbyte_loop_e:
83 NOP;
84
85.Ldifferent:
86 R0 = R0 - R1;
87 P3 = I1;
88 RTS;
89
90.Lquad_different:
91 /* We've read two quads which don't match.
92 * Can't just compare them, because we're
93 * a little-endian machine, so the MSBs of
94 * the regs occur at later addresses in the
95 * string.
96 * Arrange to re-read those two quads again,
97 * byte-by-byte.
98 */
99 P0 += -4; /* back up to the start of the */
100 P3 = I0; /* quads, and increase the*/
101 P2 += 4; /* remainder count*/
102 P3 += -4;
103 JUMP .Lbytes;
104
105.Lfinished:
106 R0 = 0;
107 P3 = I1;
108 RTS;
109
110.size _memcmp,.-_memcmp