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#include "common.h"
/*****************************************************************************
*
* CRC error protection package
*
*****************************************************************************/
void
CRC_calc (frame_params * fr_ps,
unsigned int bit_alloc[2][SBLIMIT],
unsigned int scfsi[2][SBLIMIT], unsigned int *crc)
{
int i, k;
layer *info = fr_ps->header;
int stereo = fr_ps->stereo;
int sblimit = fr_ps->sblimit;
int jsbound = fr_ps->jsbound;
al_table *alloc = fr_ps->alloc;
*crc = 0xffff; /* changed from '0' 92-08-11 shn */
update_CRC (info->bitrate_index, 4, crc);
update_CRC (info->sampling_frequency, 2, crc);
update_CRC (info->padding, 1, crc);
update_CRC (info->extension, 1, crc);
update_CRC (info->mode, 2, crc);
update_CRC (info->mode_ext, 2, crc);
update_CRC (info->copyright, 1, crc);
update_CRC (info->original, 1, crc);
update_CRC (info->emphasis, 2, crc);
for (i = 0; i < sblimit; i++)
for (k = 0; k < ((i < jsbound) ? stereo : 1); k++)
update_CRC (bit_alloc[k][i], (*alloc)[i][0].bits, crc);
for (i = 0; i < sblimit; i++)
for (k = 0; k < stereo; k++)
if (bit_alloc[k][i])
update_CRC (scfsi[k][i], 2, crc);
}
void
update_CRC (unsigned int data, unsigned int length, unsigned int *crc)
{
unsigned int masking, carry;
masking = 1 << length;
while ((masking >>= 1))
{
carry = *crc & 0x8000;
*crc <<= 1;
if (!carry ^ !(data & masking))
*crc ^= CRC16_POLYNOMIAL;
}
*crc &= 0xffff;
}
void
CRC_calcDAB (frame_params * fr_ps,
unsigned int bit_alloc[2][SBLIMIT],
unsigned int scfsi[2][SBLIMIT],
unsigned int scalar[2][3][SBLIMIT],
unsigned int *crc, int packed)
{
int i, j, k;
int stereo = fr_ps->stereo;
int nb_scalar;
int f[5] = { 0, 4, 8, 16, 30 };
int first, last;
first = f[packed];
last = f[packed + 1];
if (last > fr_ps->sblimit)
last = fr_ps->sblimit;
nb_scalar = 0;
*crc = 0x0;
for (i = first; i < last; i++)
for (k = 0; k < stereo; k++)
if (bit_alloc[k][i]) /* above jsbound, bit_alloc[0][i] == ba[1][i] */
switch (scfsi[k][i])
{
case 0:
for (j = 0; j < 3; j++)
{
nb_scalar++;
update_CRCDAB (scalar[k][j][i] >> 3, 3, crc);
}
break;
case 1:
case 3:
nb_scalar += 2;
update_CRCDAB (scalar[k][0][i] >> 3, 3, crc);
update_CRCDAB (scalar[k][2][i] >> 3, 3, crc);
break;
case 2:
nb_scalar++;
update_CRCDAB (scalar[k][0][i] >> 3, 3, crc);
}
}
void
update_CRCDAB (unsigned int data, unsigned int length, unsigned int *crc)
{
unsigned int masking, carry;
masking = 1 << length;
while ((masking >>= 1))
{
carry = *crc & 0x80;
*crc <<= 1;
if (!carry ^ !(data & masking))
*crc ^= CRC8_POLYNOMIAL;
}
*crc &= 0xff;
}
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