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Move library tree where it belongs

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ra
2010-01-24 09:19:39 +00:00
parent e74978ba77
commit 58caf78a86
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lib-src/twolame/libtwolame/crc.c Normal file
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/*
* TwoLAME: an optimized MPEG Audio Layer Two encoder
*
* Copyright (C) 2001-2004 Michael Cheng
* Copyright (C) 2004-2006 The TwoLAME Project
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id: crc.c,v 1.3 2008-02-01 19:44:31 richardash1981 Exp $
*
*/
#include <stdio.h>
#include <string.h>
#include "twolame.h"
#include "common.h"
#include "bitbuffer.h"
#include "encode.h"
#include "crc.h"
static unsigned int crc_update(unsigned int value, unsigned int crc, unsigned int nbBit)
{
int i;
value <<= 8;
for (i = 0; i < nbBit; i++) {
value <<= 1;
crc <<= 1;
if (((crc ^ value) & 0x10000))
crc ^= CRC16_POLYNOMIAL;
}
return crc;
}
/*
* The CRC is based on the second two bytes of the MPEG audio header
* and then the bits up and until the scale-factor bits.
*/
void crc_writeheader( unsigned char *bitstream, int bit_count )
{
unsigned int crc = 0xffff; /* (jo) init crc16 for error_protection */
int whole_bytes = (bit_count>>3);
int byte;
// Calculate the CRC on the second two bytes of the header
crc = crc_update(bitstream[2], crc, 8);
crc = crc_update(bitstream[3], crc, 8);
// Calculate CRC on whole bytes after CRC
for(byte=6; byte<(whole_bytes+6); byte++)
{
crc = crc_update(bitstream[byte], crc, 8);
}
// Calculate CRC on remaining bits
if(bit_count & 7)
{
crc = crc_update(bitstream[byte], crc, bit_count&7);
}
// Insert the CRC into the 16-bits after the header
bitstream[4] = crc >> 8;
bitstream[5] = crc & 0xFF;
}
// vim:ts=4:sw=4:nowrap: