2acc0ac542
later. We still need to hunt down snippets used that are not. 1324 modified files... http://www.rockbox.org/mail/archive/rockbox-dev-archive-2008-06/0060.shtml git-svn-id: svn://svn.rockbox.org/rockbox/trunk@17847 a1c6a512-1295-4272-9138-f99709370657
63 lines
2.4 KiB
C
63 lines
2.4 KiB
C
/***************************************************************************
|
|
* __________ __ ___.
|
|
* 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;
|
|
}
|
|
|