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Aubrey.Li3f0606a2007-03-09 13:38:44 +08001/*
Aubrey Li155fd762007-04-05 18:31:18 +08002 * File: memcmp.S
Aubrey.Li3f0606a2007-03-09 13:38:44 +08003 *
Aubrey Li155fd762007-04-05 18:31:18 +08004 * Copyright 2004-2007 Analog Devices Inc.
5 * Enter bugs at http://blackfin.uclinux.org/
Aubrey.Li3f0606a2007-03-09 13:38:44 +08006 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, see the file COPYING, or write
19 * to the Free Software Foundation, Inc.,
20 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23.align 2
24
25/*
26 * C Library function MEMCMP
27 * R0 = First Address
28 * R1 = Second Address
29 * R2 = count
30 * Favours word aligned data.
31 */
32
33.globl _memcmp;
34_memcmp:
35 I1 = P3;
36 P0 = R0; /* P0 = s1 address */
37 P3 = R1; /* P3 = s2 Address */
38 P2 = R2 ; /* P2 = count */
39 CC = R2 <= 7(IU);
40 IF CC JUMP .Ltoo_small;
41 I0 = R1; /* s2 */
42 R1 = R1 | R0; /* OR addresses together */
43 R1 <<= 30; /* check bottom two bits */
44 CC = AZ; /* AZ set if zero. */
45 IF !CC JUMP .Lbytes ; /* Jump if addrs not aligned. */
46
47 P1 = P2 >> 2; /* count = n/4 */
48 R3 = 3;
49 R2 = R2 & R3; /* remainder */
50 P2 = R2; /* set remainder */
51
52 LSETUP (.Lquad_loop_s , .Lquad_loop_e) LC0=P1;
53.Lquad_loop_s:
54 NOP;
55 R0 = [P0++];
56 R1 = [I0++];
57 CC = R0 == R1;
58 IF !CC JUMP .Lquad_different;
59.Lquad_loop_e:
60 NOP;
61
62 P3 = I0; /* s2 */
63.Ltoo_small:
64 CC = P2 == 0; /* Check zero count*/
65 IF CC JUMP .Lfinished; /* very unlikely*/
66
67.Lbytes:
68 LSETUP (.Lbyte_loop_s , .Lbyte_loop_e) LC0=P2;
69.Lbyte_loop_s:
70 R1 = B[P3++](Z); /* *s2 */
71 R0 = B[P0++](Z); /* *s1 */
72 CC = R0 == R1;
73 IF !CC JUMP .Ldifferent;
74.Lbyte_loop_e:
75 NOP;
76
77.Ldifferent:
78 R0 = R0 - R1;
79 P3 = I1;
80 RTS;
81
82.Lquad_different:
83/* We've read two quads which don't match.
84 * Can't just compare them, because we're
85 * a little-endian machine, so the MSBs of
86 * the regs occur at later addresses in the
87 * string.
88 * Arrange to re-read those two quads again,
89 * byte-by-byte.
90 */
91 P0 += -4; /* back up to the start of the */
92 P3 = I0; /* quads, and increase the*/
93 P2 += 4; /* remainder count*/
94 P3 += -4;
95 JUMP .Lbytes;
96
97.Lfinished:
98 R0 = 0;
99 P3 = I1;
100 RTS;