diff options
Diffstat (limited to 'firmware/common/crc32.c')
-rw-r--r-- | firmware/common/crc32.c | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/firmware/common/crc32.c b/firmware/common/crc32.c new file mode 100644 index 0000000000..18ee6ac710 --- /dev/null +++ b/firmware/common/crc32.c | |||
@@ -0,0 +1,57 @@ | |||
1 | /*************************************************************************** | ||
2 | * __________ __ ___. | ||
3 | * Open \______ \ ____ ____ | | _\_ |__ _______ ___ | ||
4 | * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / | ||
5 | * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < | ||
6 | * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ | ||
7 | * \/ \/ \/ \/ \/ | ||
8 | * $Id$ | ||
9 | * | ||
10 | * Copyright (C) 2003 Jörg Hohensohn [IDC]Dragon | ||
11 | * | ||
12 | * All files in this archive are subject to the GNU General Public License. | ||
13 | * See the file COPYING in the source tree root for full license agreement. | ||
14 | * | ||
15 | * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY | ||
16 | * KIND, either express or implied. | ||
17 | * | ||
18 | ****************************************************************************/ | ||
19 | |||
20 | /* Code copied from firmware_flash plugin. */ | ||
21 | |||
22 | /* Tool function to calculate a CRC32 across some buffer */ | ||
23 | /* third argument is either 0xFFFFFFFF to start or value from last piece */ | ||
24 | unsigned crc_32(unsigned char* buf, unsigned len, unsigned crc32) | ||
25 | { | ||
26 | /* CCITT standard polynomial 0x04C11DB7 */ | ||
27 | static const unsigned crc32_lookup[16] = | ||
28 | { /* lookup table for 4 bits at a time is affordable */ | ||
29 | 0x00000000, 0x04C11DB7, 0x09823B6E, 0x0D4326D9, | ||
30 | 0x130476DC, 0x17C56B6B, 0x1A864DB2, 0x1E475005, | ||
31 | 0x2608EDB8, 0x22C9F00F, 0x2F8AD6D6, 0x2B4BCB61, | ||
32 | 0x350C9B64, 0x31CD86D3, 0x3C8EA00A, 0x384FBDBD | ||
33 | }; | ||
34 | |||
35 | unsigned char byte; | ||
36 | unsigned t; | ||
37 | |||
38 | while (len--) | ||
39 | { | ||
40 | byte = *buf++; /* get one byte of data */ | ||
41 | |||
42 | /* upper nibble of our data */ | ||
43 | t = crc32 >> 28; /* extract the 4 most significant bits */ | ||
44 | t ^= byte >> 4; /* XOR in 4 bits of data into the extracted bits */ | ||
45 | crc32 <<= 4; /* shift the CRC register left 4 bits */ | ||
46 | crc32 ^= crc32_lookup[t]; /* do the table lookup and XOR the result */ | ||
47 | |||
48 | /* lower nibble of our data */ | ||
49 | t = crc32 >> 28; /* extract the 4 most significant bits */ | ||
50 | t ^= byte & 0x0F; /* XOR in 4 bits of data into the extracted bits */ | ||
51 | crc32 <<= 4; /* shift the CRC register left 4 bits */ | ||
52 | crc32 ^= crc32_lookup[t]; /* do the table lookup and XOR the result */ | ||
53 | } | ||
54 | |||
55 | return crc32; | ||
56 | } | ||
57 | |||