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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: layer2.c,v 1.2 2009/03/01 15:27:05 jpff 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 II_decode_bitalloc(mpadec_t mpadec, uint8_t *bit_alloc,
uint8_t *scalefac)
{
register struct mpadec_t *mpa = (struct mpadec_t *)mpadec;
alloc_table_t *alloc = mpa->frame.alloc_table;
uint8_t *scfsi, *ba = bit_alloc, *scf = scalefac;
unsigned i, step, sblimit2, sblimit = mpa->frame.sblimit;
uint32_t crclen = mpa->bytes_left;
uint8_t scfsi_buf[2*SBLIMIT];
if (mpa->frame.channels > 1) {
unsigned jsbound = mpa->frame.jsbound;
sblimit2 = sblimit << 1;
for (i = jsbound; i; i--, alloc += ((int64_t)(1) << step)) {
step = alloc->bits;
*ba++ = (uint8_t)GETBITS(step);
*ba++ = (uint8_t)GETBITS(step);
}
for (i = sblimit - jsbound; i; i--, alloc += ((int64_t)(1) << step)) {
step = alloc->bits;
ba[0] = (uint8_t)GETBITS(step);
ba[1] = ba[0];
ba += 2;
}
ba = bit_alloc;
scfsi = scfsi_buf;
for (i = sblimit2; i; i--) if (*ba++) *scfsi++ = (uint8_t)GETBITS(2);
} else {
sblimit2 = sblimit;
for (i = sblimit; i; i--, alloc += ((int64_t)(1) << step)) {
step = alloc->bits;
*ba++ = (uint8_t)GETBITS(step);
}
ba = bit_alloc;
scfsi = scfsi_buf;
for (i = sblimit; i; i--) if (*ba++) *scfsi++ = (uint8_t)GETBITS(2);
}
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;
scfsi = scfsi_buf;
for (i = sblimit2; i; i--) {
if (*ba++) {
switch (*scfsi++) {
case 0:
scf[0] = (uint8_t)GETBITS(6);
scf[1] = (uint8_t)GETBITS(6);
scf[2] = (uint8_t)GETBITS(6);
break;
case 1:
scf[0] = (uint8_t)GETBITS(6);
scf[1] = scf[0];
scf[2] = (uint8_t)GETBITS(6);
break;
case 2:
scf[0] = (uint8_t)GETBITS(6);
scf[1] = scf[2] = scf[0];
break;
default:
scf[0] = (uint8_t)GETBITS(6);
scf[1] = (uint8_t)GETBITS(6);
scf[2] = scf[1];
break;
}
scf += 3;
}
}
}
static void II_decode_samples(mpadec_t mpadec, uint8_t *bit_alloc,
uint8_t *scalefac, MYFLT fraction[2][4][SBLIMIT],
int x1)
{
register struct mpadec_t *mpa = (struct mpadec_t *)mpadec;
alloc_table_t *alloc = mpa->frame.alloc_table, *alloc2;
uint8_t *ba = bit_alloc, *scf = scalefac;
unsigned i, j, k, step, sblimit = mpa->frame.sblimit;
unsigned jsbound = mpa->frame.jsbound;
for (i = 0; i < jsbound; i++, alloc += ((int64_t)1) << step) {
step = alloc->bits;
for (j = 0; j < (unsigned)mpa->frame.channels; j++) {
unsigned b = *ba++; int d;
if (b) {
alloc2 = alloc + b;
k = alloc2->bits;
d = alloc2->d;
if (d < 0) {
register MYFLT cm = mpa->tables.muls[k][scf[x1]];
fraction[j][0][i] = ((MYFLT)((int)GETBITS(k) + d))*cm;
fraction[j][1][i] = ((MYFLT)((int)GETBITS(k) + d))*cm;
fraction[j][2][i] = ((MYFLT)((int)GETBITS(k) + d))*cm;
} else {
unsigned idx = GETBITS(k), m = scf[x1];
uint8_t *tab = (mpa->tables.mp2tables[d] + 3*idx);
fraction[j][0][i] = mpa->tables.muls[*tab++][m];
fraction[j][1][i] = mpa->tables.muls[*tab++][m];
fraction[j][2][i] = mpa->tables.muls[*tab][m];
}
scf += 3;
} else fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
}
}
for (i = jsbound; i < sblimit; i++, alloc += ((int64_t)(1) << step)) {
unsigned b = ba[1]; int d;
step = alloc->bits;
ba += 2;
if (b) {
alloc2 = alloc + b;
k = alloc2->bits;
d = alloc2->d;
if (d < 0) {
register MYFLT cm = mpa->tables.muls[k][scf[x1 + 3]];
fraction[1][0][i] = fraction[0][0][i] = ((MYFLT)((int)GETBITS(k) + d))*cm;
fraction[1][1][i] = fraction[0][1][i] = ((MYFLT)((int)GETBITS(k) + d))*cm;
fraction[1][2][i] = fraction[0][2][i] = ((MYFLT)((int)GETBITS(k) + d))*cm;
cm = mpa->tables.muls[k][scf[x1]];
fraction[0][0][i] *= cm;
fraction[0][1][i] *= cm;
fraction[0][2][i] *= cm;
} else {
unsigned idx = GETBITS(k), m1 = scf[x1], m2 = scf[x1 + 3];
uint8_t *tab = (mpa->tables.mp2tables[d] + 3*idx);
fraction[0][0][i] = mpa->tables.muls[*tab][m1];
fraction[1][0][i] = mpa->tables.muls[*tab++][m2];
fraction[0][1][i] = mpa->tables.muls[*tab][m1];
fraction[1][1][i] = mpa->tables.muls[*tab++][m2];
fraction[0][2][i] = mpa->tables.muls[*tab][m1];
fraction[1][2][i] = mpa->tables.muls[*tab][m2];
}
scf += 6;
} else fraction[0][0][i] = fraction[0][1][i] = fraction[0][2][i] =
fraction[1][0][i] = fraction[1][1][i] = fraction[1][2][i] = 0.0;
}
if (sblimit > (unsigned)mpa->frame.downsample_sblimit)
sblimit = mpa->frame.downsample_sblimit;
for (i = sblimit; i < SBLIMIT; i++)
for (j = 0; j < (unsigned)mpa->frame.channels; j++)
fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
}
void decode_layer2(mpadec_t mpadec, uint8_t *buffer)
{
register struct mpadec_t *mpa = (struct mpadec_t *)mpadec;
int i, j, table, single;
MYFLT fraction[2][4][SBLIMIT];
uint8_t bit_alloc[2*SBLIMIT];
uint8_t scalefac[3*2*SBLIMIT];
static uint8_t sblimits[5] = { 27 , 30 , 8, 12 , 30 };
static uint8_t translate[3][2][16] =
{ { { 0, 2, 2, 2, 2, 2, 2, 0, 0, 0, 1, 1, 1, 1, 1, 0 },
{ 0, 2, 2, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0 } },
{ { 0, 2, 2, 2, 2, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
{ 0, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 } },
{ { 0, 3, 3, 3, 3, 3, 3, 0, 0, 0, 1, 1, 1, 1, 1, 0 },
{ 0, 3, 3, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0 } } };
mpa->error = FALSE;
mpa->bits_left = 0;
if (mpa->frame.LSF) table = 4;
else
table =
translate[mpa->frame.frequency_index]
[2 - mpa->frame.channels][mpa->frame.bitrate_index];
mpa->frame.alloc_table = alloc_tables[table];
mpa->frame.sblimit = sblimits[table];
mpa->frame.jsbound =
(uint8_t)((mpa->frame.mode == MPG_MD_JOINT_STEREO) ?
((mpa->frame.mode_ext + 1) << 2) : mpa->frame.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;
II_decode_bitalloc(mpa, bit_alloc, scalefac);
for (i = 0; i < SCALE_BLOCK; i++) {
II_decode_samples(mpa, bit_alloc, scalefac, fraction, i >> 2);
if (!single) for (j = 0; j < 3; j++) {
register int k;
for (k = 0; k < SBLIMIT; k++)
fraction[0][j][k] = 0.5*(fraction[0][j][k] + fraction[1][j][k]);
}
if (single < 0) {
for (j = 0; j < 3; j++, buffer += mpa->synth_size) {
mpa->synth_func(mpa, fraction[0][j], 0, buffer);
mpa->synth_func(mpa, fraction[1][j], 1, buffer);
}
} else if (!single) {
for (j = 0; j < 3; j++, buffer += mpa->synth_size) {
mpa->synth_func(mpa, fraction[0][j], 0, buffer);
}
} else {
for (j = 0; j < 3; j++, buffer += mpa->synth_size) {
mpa->synth_func(mpa, fraction[single - 1][j], 0, buffer);
}
}
}
{
register unsigned n = mpa->bits_left >> 3;
mpa->next_byte -= n;
mpa->bytes_left += n;
mpa->reservoir_size = 0;
}
}
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