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/*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <gpxe/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;
}
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