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55 lines
1.5 KiB
C
55 lines
1.5 KiB
C
/*
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* Little-endian CRC32 implementation.
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*
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* Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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FILE_LICENCE ( GPL2_OR_LATER );
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#include <ipxe/crc32.h>
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#define CRCPOLY 0xedb88320
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/**
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* Calculate 32-bit little-endian CRC checksum
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*
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* @v seed Initial value
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* @v data Data to checksum
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* @v len Length of data
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*
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* Usually @a seed is initially zero or all one bits, depending on the
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* protocol. To continue a CRC checksum over multiple calls, pass the
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* return value from one call as the @a seed parameter to the next.
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*/
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u32 crc32_le ( u32 seed, const void *data, size_t len )
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{
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u32 crc = seed;
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const u8 *src = data;
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u32 mult;
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int i;
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while ( len-- ) {
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crc ^= *src++;
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for ( i = 0; i < 8; i++ ) {
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mult = ( crc & 1 ) ? CRCPOLY : 0;
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crc = ( crc >> 1 ) ^ mult;
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}
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}
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return crc;
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}
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