contrib: add ram loader src code
[openocd.git] / contrib / loaders / checksum / armv7m_crc.s
1 /***************************************************************************
2  *   Copyright (C) 2010 by Spencer Oliver                                  *
3  *   spen@spen-soft.co.uk                                                  *
4  *                                                                         *
5  *   This program is free software; you can redistribute it and/or modify  *
6  *   it under the terms of the GNU General Public License as published by  *
7  *   the Free Software Foundation; either version 2 of the License, or     *
8  *   (at your option) any later version.                                   *
9  *                                                                         *
10  *   This program is distributed in the hope that it will be useful,       *
11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
13  *   GNU General Public License for more details.                          *
14  *                                                                         *
15  *   You should have received a copy of the GNU General Public License     *
16  *   along with this program; if not, write to the                         *
17  *   Free Software Foundation, Inc.,                                       *
18  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
19  ***************************************************************************/
20
21 /*
22         parameters:
23         r0 - address in - crc out
24         r1 - char count
25 */
26
27         .text
28         .syntax unified
29         .cpu cortex-m3
30         .thumb
31         .thumb_func
32         
33         .align  2
34
35 _start:
36 main:   
37         mov             r2, r0
38         mov             r0, #0xffffffff /* crc */
39         mov             r3, r1
40         mov             r4, #0
41         b               ncomp
42 nbyte:
43         ldrb    r1, [r2, r4]
44
45         ldr             r7, CRC32XOR
46         eor             r0, r0, r1, asl #24
47         mov             r5, #0
48 loop:
49         cmp             r0, #0
50         mov             r6, r0, asl #1
51         add             r5, r5, #1
52         mov             r0, r6
53         it              lt
54         eorlt   r0, r6, r7
55         cmp             r5, #8
56         bne             loop
57         
58         add             r4, r4, #1
59 ncomp:
60         cmp             r4, r3
61         bne             nbyte
62         bkpt    #0
63
64 CRC32XOR:       .word   0x04c11db7
65
66         .end