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/*
* mpadec - MPEG audio decoder
* Copyright (C) 2002-2004 Dmitriy Startsev (dstartsev@rambler.ru)
*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/* $Id: layer1.c,v 1.1.1.1 2004/07/27 02:57:18 metal_man Exp $ */
#include "mpadec_internal.h"
extern const uint32_t bitmask[17];
extern alloc_table_t *alloc_tables[5];
extern unsigned mpa_getbits(mpadec_t mpadec, int n);
extern uint16_t update_crc(uint16_t init, uint8_t *buf, int length);
static void I_decode_bitalloc(mpadec_t mpadec, uint8_t *bit_alloc,
uint8_t *scalefac)
{
register struct mpadec_t *mpa = (struct mpadec_t *)mpadec;
uint8_t *ba = bit_alloc, *scf = scalefac;
uint32_t crclen = mpa->bytes_left;
if (mpa->frame.channels > 1) {
unsigned i, jsbound = mpa->frame.jsbound;
for (i = jsbound; i; i--) {
*ba++ = (uint8_t)GETBITS(4);
*ba++ = (uint8_t)GETBITS(4);
}
for (i = (SBLIMIT - jsbound); i; i--) *ba++ = (uint8_t)GETBITS(4);
if (mpa->config.crc && mpa->frame.CRC) {
crclen -= mpa->bytes_left;
mpa->crc = update_crc(mpa->crc, mpa->next_byte - crclen,
((crclen << 3) - mpa->bits_left));
if (mpa->crc != mpa->frame.crc) mpa->error = TRUE;
}
ba = bit_alloc;
for (i = jsbound; i; i--) {
if (*ba++) *scf++ = (uint8_t)GETBITS(6);
if (*ba++) *scf++ = (uint8_t)GETBITS(6);
}
for (i = (SBLIMIT - jsbound); i; i--) {
if (*ba++) {
*scf++ = (uint8_t)GETBITS(6);
*scf++ = (uint8_t)GETBITS(6);
}
}
} else {
register unsigned i;
for (i = SBLIMIT; i; i--) *ba++ = (uint8_t)GETBITS(4);
if (mpa->config.crc && mpa->frame.CRC) {
crclen -= mpa->bytes_left;
mpa->crc = update_crc(mpa->crc, mpa->next_byte - crclen,
((crclen << 3) - mpa->bits_left));
if (mpa->crc != mpa->frame.crc) mpa->error = TRUE;
}
ba = bit_alloc;
for (i = SBLIMIT; i; i--) if (*ba++) *scf++ = (uint8_t)GETBITS(6);
}
}
static void I_decode_samples(mpadec_t mpadec, uint8_t *bit_alloc,
uint8_t *scalefac, MYFLT fraction[2][SBLIMIT])
{
register struct mpadec_t *mpa = (struct mpadec_t *)mpadec;
uint8_t *ba = bit_alloc, *scf = scalefac;
unsigned i, n;
int cnst = -1;
if (mpa->frame.channels > 1) {
unsigned jsbound = mpa->frame.jsbound;
MYFLT *f0 = fraction[0], *f1 = fraction[1];
for (i = jsbound; i; i--) {
if ((n = *ba++) != 0)
*f0++ = (((cnst)<<n)+GETBITS(n + 1) + 1)*mpa->tables.muls[n + 1][*scf++];
else *f0++ = 0.0;
if ((n = *ba++) != 0)
*f1++ = (((cnst)<<n) + GETBITS(n + 1) + 1)*mpa->tables.muls[n + 1][*scf++];
else *f1++ = 0.0;
}
for (i = (SBLIMIT - jsbound); i; i--) {
if ((n = *ba++) != 0) {
register MYFLT tmp = (((cnst) << n) + GETBITS(n + 1) + 1);
*f0++ = tmp*mpa->tables.muls[n + 1][*scf++];
*f1++ = tmp*mpa->tables.muls[n + 1][*scf++];
} else *f0++ = *f1++ = 0.0;
}
for (i = (SBLIMIT - mpa->frame.downsample_sblimit); i; i--)
*--f0 = *--f1 = 0.0;
} else {
MYFLT *f0 = fraction[0];
for (i = SBLIMIT; i; i--) {
if ((n = *ba++) != 0)
*f0++ = (((cnst)<<n) + GETBITS(n + 1) + 1)*mpa->tables.muls[n + 1][*scf++];
else *f0++ = 0.0;
}
for (i = (SBLIMIT - mpa->frame.downsample_sblimit); i; i--) *--f0 = 0.0;
}
}
void decode_layer1(mpadec_t mpadec, uint8_t *buffer)
{
register struct mpadec_t *mpa = (struct mpadec_t *)mpadec;
int i, j, single;
MYFLT fraction[2][SBLIMIT];
uint8_t bit_alloc[2*SBLIMIT];
uint8_t scalefac[2*SBLIMIT];
mpa->error = FALSE;
mpa->bits_left = 0;
mpa->frame.jsbound =
(uint8_t)((mpa->frame.mode == MPG_MD_JOINT_STEREO) ?
((mpa->frame.mode_ext + 1) << 2) : SBLIMIT);
if (mpa->frame.channels > 1) switch (mpa->config.mode) {
case MPADEC_CONFIG_MONO: single = 0; break;
case MPADEC_CONFIG_CHANNEL1: single = 1; break;
case MPADEC_CONFIG_CHANNEL2: single = 2; break;
default: single = -1; break;
} else single = 1;
I_decode_bitalloc(mpa, bit_alloc, scalefac);
for (i = 0; i < SCALE_BLOCK; i++) {
I_decode_samples(mpa, bit_alloc, scalefac, fraction);
if (!single)
for (j = 0; j < SBLIMIT; j++)
fraction[0][j] = 0.5*(fraction[0][j] + fraction[1][j]);
if (single < 0) {
mpa->synth_func(mpa, fraction[0], 0, buffer);
mpa->synth_func(mpa, fraction[1], 1, buffer);
} else if (!single) {
mpa->synth_func(mpa, fraction[0], 0, buffer);
} else {
mpa->synth_func(mpa, fraction[single - 1], 0, buffer);
}
buffer += mpa->synth_size;
}
{
register unsigned n = mpa->bits_left >> 3;
mpa->next_byte -= n;
mpa->bytes_left += n;
mpa->reservoir_size = 0;
}
}
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