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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2003 Jörg Hohensohn [IDC]Dragon
*
* 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 (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
/* Code copied from firmware_flash plugin. */
#include "crc32.h"
/* Tool function to calculate a CRC32 across some buffer */
/* third argument is either 0xFFFFFFFF to start or value from last piece */
unsigned crc_32(const void *src, unsigned len, unsigned crc32)
{
const unsigned char *buf = (const unsigned char *)src;
/* CCITT standard polynomial 0x04C11DB7 */
static const unsigned crc32_lookup[16] =
{ /* lookup table for 4 bits at a time is affordable */
0x00000000, 0x04C11DB7, 0x09823B6E, 0x0D4326D9,
0x130476DC, 0x17C56B6B, 0x1A864DB2, 0x1E475005,
0x2608EDB8, 0x22C9F00F, 0x2F8AD6D6, 0x2B4BCB61,
0x350C9B64, 0x31CD86D3, 0x3C8EA00A, 0x384FBDBD
};
unsigned char byte;
unsigned t;
while (len--)
{
byte = *buf++; /* get one byte of data */
/* upper nibble of our data */
t = crc32 >> 28; /* extract the 4 most significant bits */
t ^= byte >> 4; /* XOR in 4 bits of data into the extracted bits */
crc32 <<= 4; /* shift the CRC register left 4 bits */
crc32 ^= crc32_lookup[t]; /* do the table lookup and XOR the result */
/* lower nibble of our data */
t = crc32 >> 28; /* extract the 4 most significant bits */
t ^= byte & 0x0F; /* XOR in 4 bits of data into the extracted bits */
crc32 <<= 4; /* shift the CRC register left 4 bits */
crc32 ^= crc32_lookup[t]; /* do the table lookup and XOR the result */
}
return crc32;
}
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