[fdt] Add ability to parse a MAC address from a flattened device tree
[ipxe.git] / src / crypto / crc32.c
1 /*
2 * Little-endian CRC32 implementation.
3 *
4 * Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation; either version 2 of the
9 * License, or any later version.
10 *
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
19 * 02110-1301, USA.
20 */
21
22 FILE_LICENCE ( GPL2_OR_LATER );
23
24 #include <ipxe/crc32.h>
25
26 #define CRCPOLY 0xedb88320
27
28 /**
29 * Calculate 32-bit little-endian CRC checksum
30 *
31 * @v seed Initial value
32 * @v data Data to checksum
33 * @v len Length of data
34 *
35 * Usually @a seed is initially zero or all one bits, depending on the
36 * protocol. To continue a CRC checksum over multiple calls, pass the
37 * return value from one call as the @a seed parameter to the next.
38 */
39 u32 crc32_le ( u32 seed, const void *data, size_t len )
40 {
41 u32 crc = seed;
42 const u8 *src = data;
43 u32 mult;
44 int i;
45
46 while ( len-- ) {
47 crc ^= *src++;
48 for ( i = 0; i < 8; i++ ) {
49 mult = ( crc & 1 ) ? CRCPOLY : 0;
50 crc = ( crc >> 1 ) ^ mult;
51 }
52 }
53
54 return crc;
55 }