56 lines
1.5 KiB
C
56 lines
1.5 KiB
C
/*
|
|
* Little-endian CRC32 implementation.
|
|
*
|
|
* Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License as
|
|
* published by the Free Software Foundation; either version 2 of the
|
|
* License, or any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful, but
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
|
|
* 02110-1301, USA.
|
|
*/
|
|
|
|
FILE_LICENCE ( GPL2_OR_LATER );
|
|
|
|
#include <ipxe/crc32.h>
|
|
|
|
#define CRCPOLY 0xedb88320
|
|
|
|
/**
|
|
* Calculate 32-bit little-endian CRC checksum
|
|
*
|
|
* @v seed Initial value
|
|
* @v data Data to checksum
|
|
* @v len Length of data
|
|
*
|
|
* Usually @a seed is initially zero or all one bits, depending on the
|
|
* protocol. To continue a CRC checksum over multiple calls, pass the
|
|
* return value from one call as the @a seed parameter to the next.
|
|
*/
|
|
u32 crc32_le ( u32 seed, const void *data, size_t len )
|
|
{
|
|
u32 crc = seed;
|
|
const u8 *src = data;
|
|
u32 mult;
|
|
int i;
|
|
|
|
while ( len-- ) {
|
|
crc ^= *src++;
|
|
for ( i = 0; i < 8; i++ ) {
|
|
mult = ( crc & 1 ) ? CRCPOLY : 0;
|
|
crc = ( crc >> 1 ) ^ mult;
|
|
}
|
|
}
|
|
|
|
return crc;
|
|
}
|