Merge with git://www.denx.de/git/u-boot.git
[platform/kernel/u-boot.git] / lib_blackfin / memcmp.S
1 /*
2  * File:         arch/blackfin/lib/memcmp.S
3  * Based on:
4  * Author:
5  *
6  * Created:
7  * Description:
8  *
9  * Rev:          $Id: memcmp.S 2386 2006-11-01 04:57:26Z magicyang $
10  *
11  * Modified:
12  *               Copyright 2004-2006 Analog Devices Inc.
13  *
14  * Bugs:         Enter bugs at http://blackfin.uclinux.org/
15  *
16  * This program is free software; you can redistribute it and/or modify
17  * it under the terms of the GNU General Public License as published by
18  * the Free Software Foundation; either version 2 of the License, or
19  * (at your option) any later version.
20  *
21  * This program is distributed in the hope that it will be useful,
22  * but WITHOUT ANY WARRANTY; without even the implied warranty of
23  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
24  * GNU General Public License for more details.
25  *
26  * You should have received a copy of the GNU General Public License
27  * along with this program; if not, see the file COPYING, or write
28  * to the Free Software Foundation, Inc.,
29  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
30  */
31
32 .align 2
33
34 /*
35  * C Library function MEMCMP
36  * R0 = First Address
37  * R1 = Second Address
38  * R2 = count
39  * Favours word aligned data.
40  */
41
42 .globl _memcmp;
43 _memcmp:
44         I1 = P3;
45         P0 = R0;                        /* P0 = s1 address */
46         P3 = R1;                        /* P3 = s2 Address  */
47         P2 = R2 ;                       /* P2 = count */
48         CC = R2 <= 7(IU);
49         IF CC JUMP  .Ltoo_small;
50         I0 = R1;                        /* s2 */
51         R1 = R1 | R0;           /* OR addresses together */
52         R1 <<= 30;              /* check bottom two bits */
53         CC =  AZ;                       /* AZ set if zero. */
54         IF !CC JUMP  .Lbytes ;  /* Jump if addrs not aligned. */
55
56         P1 = P2 >> 2;           /* count = n/4 */
57         R3 =  3;
58         R2 = R2 & R3;           /* remainder */
59         P2 = R2;                        /* set remainder */
60
61         LSETUP (.Lquad_loop_s , .Lquad_loop_e) LC0=P1;
62 .Lquad_loop_s:
63         NOP;
64         R0 = [P0++];
65         R1 = [I0++];
66         CC = R0 == R1;
67         IF !CC JUMP .Lquad_different;
68 .Lquad_loop_e:
69         NOP;
70
71         P3 = I0;                        /* s2 */
72 .Ltoo_small:
73         CC = P2 == 0;           /* Check zero count*/
74         IF CC JUMP .Lfinished;  /* very unlikely*/
75
76 .Lbytes:
77         LSETUP (.Lbyte_loop_s , .Lbyte_loop_e) LC0=P2;
78 .Lbyte_loop_s:
79         R1 = B[P3++](Z);        /* *s2 */
80         R0 = B[P0++](Z);        /* *s1 */
81         CC = R0 == R1;
82         IF !CC JUMP .Ldifferent;
83 .Lbyte_loop_e:
84         NOP;
85
86 .Ldifferent:
87         R0 = R0 - R1;
88         P3 = I1;
89         RTS;
90
91 .Lquad_different:
92 /* We've read two quads which don't match.
93  * Can't just compare them, because we're
94  * a little-endian machine, so the MSBs of
95  * the regs occur at later addresses in the
96  * string.
97  * Arrange to re-read those two quads again,
98  * byte-by-byte.
99  */
100         P0 += -4;               /* back up to the start of the */
101         P3 = I0;                /* quads, and increase the*/
102         P2 += 4;                /* remainder count*/
103         P3 += -4;
104         JUMP .Lbytes;
105
106 .Lfinished:
107         R0 = 0;
108         P3 = I1;
109         RTS;