/*

* layer1.c: Mpeg Layer-1 audio decoder

*

* Copyright (C) 1999-2010 The L.A.M.E. project

*

* Initially written by Michael Hipp, see also AUTHORS and README.

*

* This library is free software; you can redistribute it and/or

* modify it under the terms of the GNU Library General Public

* License as published by the Free Software Foundation; either

* version 2 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

* Library General Public License for more details.

*

* You should have received a copy of the GNU Library 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: layer1.c,v 1.23.2.2 2010/03/22 14:17:14 robert Exp $ */

#ifdef HAVE_CONFIG_H

# include <config.h>

#endif

#include <assert.h>

#include "common.h"

#include "decode_i386.h"

#ifdef WITH_DMALLOC

#include <dmalloc.h>

#endif

#include "layer1.h"

static void

I_step_one(PMPSTR mp, unsigned int balloc[], unsigned int scale_index[2][SBLIMIT], struct frame *fr)

{

unsigned int *ba = balloc;

unsigned int *sca = (unsigned int *) scale_index;

assert(fr->stereo == 1 || fr->stereo == 2);

if (fr->stereo == 2) {

int i;

int jsbound = fr->jsbound;

for (i = 0; i < jsbound; i++) {

*ba++ = getbits(mp, 4);

*ba++ = getbits(mp, 4);

}

for (i = jsbound; i < SBLIMIT; i++)

*ba++ = getbits(mp, 4);

ba = balloc;

for (i = 0; i < jsbound; i++) {

if ((*ba++))

*sca++ = getbits(mp, 6);

if ((*ba++))

*sca++ = getbits(mp, 6);

}

for (i = jsbound; i < SBLIMIT; i++)

if ((*ba++)) {

*sca++ = getbits(mp, 6);

*sca++ = getbits(mp, 6);

}

}

else {

int i;

for (i = 0; i < SBLIMIT; i++)

*ba++ = getbits(mp, 4);

ba = balloc;

for (i = 0; i < SBLIMIT; i++)

if ((*ba++))

*sca++ = getbits(mp, 6);

}

}

static void

I_step_two(PMPSTR mp, real fraction[2][SBLIMIT], unsigned int balloc[2 * SBLIMIT],

unsigned int scale_index[2][SBLIMIT], struct frame *fr)

{

int i, n;

int smpb[2 * SBLIMIT]; /* values: 0-65535 */

int *sample;

unsigned int *ba;

unsigned int *sca = (unsigned int *) scale_index;

assert(fr->stereo == 1 || fr->stereo == 2);

if (fr->stereo == 2) {

int jsbound = fr->jsbound;

real *f0 = fraction[0];

real *f1 = fraction[1];

ba = balloc;

for (sample = smpb, i = 0; i < jsbound; i++) {

n = *ba++;

if (n)

*sample++ = getbits(mp, n + 1);

n = *ba++;

if (n)

*sample++ = getbits(mp, n + 1);

}

for (i = jsbound; i < SBLIMIT; i++) {

n = *ba++;

if (n)

*sample++ = getbits(mp, n + 1);

}

ba = balloc;

for (sample = smpb, i = 0; i < jsbound; i++) {

n = *ba++;

if (n)

*f0++ = (real) (((-1) << n) + (*sample++) + 1) * muls[n + 1][*sca++];

else

*f0++ = 0.0;

n = *ba++;

if (n)

*f1++ = (real) (((-1) << n) + (*sample++) + 1) * muls[n + 1][*sca++];

else

*f1++ = 0.0;

}

for (i = jsbound; i < SBLIMIT; i++) {

n = *ba++;

if (n) {

real samp = (real) (((-1) << n) + (*sample++) + 1);

*f0++ = samp * muls[n + 1][*sca++];

*f1++ = samp * muls[n + 1][*sca++];

}

else

*f0++ = *f1++ = 0.0;

}

for (i = fr->down_sample_sblimit; i < 32; i++)

fraction[0][i] = fraction[1][i] = 0.0;

}

else {

real *f0 = fraction[0];

ba = balloc;

for (sample = smpb, i = 0; i < SBLIMIT; i++) {

n = *ba++;

if (n)

*sample++ = getbits(mp, n + 1);

}

ba = balloc;

for (sample = smpb, i = 0; i < SBLIMIT; i++) {

n = *ba++;

if (n)

*f0++ = (real) (((-1) << n) + (*sample++) + 1) * muls[n + 1][*sca++];

else

*f0++ = 0.0;

}

for (i = fr->down_sample_sblimit; i < 32; i++)

fraction[0][i] = 0.0;

}

}

/*int do_layer1(struct frame *fr,int outmode,struct audio_info_struct *ai) */

int

do_layer1(PMPSTR mp, unsigned char *pcm_sample, int *pcm_point)

{

int clip = 0;

unsigned int balloc[2 * SBLIMIT];

unsigned int scale_index[2][SBLIMIT];

real fraction[2][SBLIMIT];

struct frame *fr = &(mp->fr);

int i, stereo = fr->stereo;

int single = fr->single;

fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ? (fr->mode_ext << 2) + 4 : 32;

if (stereo == 1 || single == 3)

single = 0;

I_step_one(mp, balloc, scale_index, fr);

for (i = 0; i < SCALE_BLOCK; i++) {

I_step_two(mp, fraction, balloc, scale_index, fr);

if (single >= 0) {

clip += synth_1to1_mono(mp, (real *) fraction[single], pcm_sample, pcm_point);

}

else {

int p1 = *pcm_point;

clip += synth_1to1(mp, (real *) fraction[0], 0, pcm_sample, &p1);

clip += synth_1to1(mp, (real *) fraction[1], 1, pcm_sample, pcm_point);

}

}

return clip;

}