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layer2.c

/* 
 * layer2.c: Mpeg Layer-2 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: layer2.c,v 1.23.2.2 2010/03/22 14:17:14 robert Exp $ */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include "common.h"
#include "layer2.h"
#include "l2tables.h"
#include "decode_i386.h"

#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif

static int grp_3tab[32 * 3] = { 0, }; /* used: 27 */
static int grp_5tab[128 * 3] = { 0, }; /* used: 125 */
static int grp_9tab[1024 * 3] = { 0, }; /* used: 729 */

void
init_layer2(void)
{
    static const double mulmul[27] = {
        0.0, -2.0 / 3.0, 2.0 / 3.0,
        2.0 / 7.0, 2.0 / 15.0, 2.0 / 31.0, 2.0 / 63.0, 2.0 / 127.0, 2.0 / 255.0,
        2.0 / 511.0, 2.0 / 1023.0, 2.0 / 2047.0, 2.0 / 4095.0, 2.0 / 8191.0,
        2.0 / 16383.0, 2.0 / 32767.0, 2.0 / 65535.0,
        -4.0 / 5.0, -2.0 / 5.0, 2.0 / 5.0, 4.0 / 5.0,
        -8.0 / 9.0, -4.0 / 9.0, -2.0 / 9.0, 2.0 / 9.0, 4.0 / 9.0, 8.0 / 9.0
    };
    static const int base[3][9] = {
        {1, 0, 2,},
        {17, 18, 0, 19, 20,},
        {21, 1, 22, 23, 0, 24, 25, 2, 26}
    };
    int     i, j, k, l, len;
    real   *table;
    static const int tablen[3] = { 3, 5, 9 };
    static int *itable, *tables[3] = { grp_3tab, grp_5tab, grp_9tab };

    for (i = 0; i < 3; i++) {
        itable = tables[i];
        len = tablen[i];
        for (j = 0; j < len; j++)
            for (k = 0; k < len; k++)
                for (l = 0; l < len; l++) {
                    *itable++ = base[i][l];
                    *itable++ = base[i][k];
                    *itable++ = base[i][j];
                }
    }

    for (k = 0; k < 27; k++) {
        double  m = mulmul[k];
        table = muls[k];
        for (j = 3, i = 0; i < 63; i++, j--)
            *table++ = (real) (m * pow(2.0, (double) j / 3.0));
        *table++ = 0.0;
    }
}


static void
II_step_one(PMPSTR mp, unsigned int *bit_alloc, int *scale, struct frame *fr)
{
    int     stereo = fr->stereo - 1;
    int     sblimit = fr->II_sblimit;
    int     jsbound = fr->jsbound;
    int     sblimit2 = fr->II_sblimit << stereo;
    struct al_table2 const *alloc1 = fr->alloc;
    int     i;
    static unsigned int scfsi_buf[64];
    unsigned int *scfsi, *bita;
    int     sc, step;

    bita = bit_alloc;
    if (stereo) {
        for (i = jsbound; i; i--, alloc1 += (1 << step)) {
            *bita++ = (char) getbits(mp, step = alloc1->bits);
            *bita++ = (char) getbits(mp, step);
        }
        for (i = sblimit - jsbound; i; i--, alloc1 += (1 << step)) {
            bita[0] = (char) getbits(mp, step = alloc1->bits);
            bita[1] = bita[0];
            bita += 2;
        }
        bita = bit_alloc;
        scfsi = scfsi_buf;
        for (i = sblimit2; i; i--)
            if (*bita++)
                *scfsi++ = (char) getbits_fast(mp, 2);
    }
    else {              /* mono */

        for (i = sblimit; i; i--, alloc1 += (1 << step))
            *bita++ = (char) getbits(mp, step = alloc1->bits);
        bita = bit_alloc;
        scfsi = scfsi_buf;
        for (i = sblimit; i; i--)
            if (*bita++)
                *scfsi++ = (char) getbits_fast(mp, 2);
    }

    bita = bit_alloc;
    scfsi = scfsi_buf;
    for (i = sblimit2; i; i--)
        if (*bita++)
            switch (*scfsi++) {
            case 0:
                *scale++ = getbits_fast(mp, 6);
                *scale++ = getbits_fast(mp, 6);
                *scale++ = getbits_fast(mp, 6);
                break;
            case 1:
                *scale++ = sc = getbits_fast(mp, 6);
                *scale++ = sc;
                *scale++ = getbits_fast(mp, 6);
                break;
            case 2:
                *scale++ = sc = getbits_fast(mp, 6);
                *scale++ = sc;
                *scale++ = sc;
                break;
            default:   /* case 3 */
                *scale++ = getbits_fast(mp, 6);
                *scale++ = sc = getbits_fast(mp, 6);
                *scale++ = sc;
                break;
            }

}

static void
II_step_two(PMPSTR mp, unsigned int *bit_alloc, real fraction[2][4][SBLIMIT], int *scale,
            struct frame *fr, int x1)
{
    int     i, j, k, ba;
    int     stereo = fr->stereo;
    int     sblimit = fr->II_sblimit;
    int     jsbound = fr->jsbound;
    struct al_table2 const *alloc2, *alloc1 = fr->alloc;
    unsigned int *bita = bit_alloc;
    int     d1, step;

    for (i = 0; i < jsbound; i++, alloc1 += (1 << step)) {
        step = alloc1->bits;
        for (j = 0; j < stereo; j++) {
            ba = *bita++;
            if (ba) {
                k = (alloc2 = alloc1 + ba)->bits;
                if ((d1 = alloc2->d) < 0) {
                    real    cm = muls[k][scale[x1]];
                    fraction[j][0][i] = ((real) ((int) getbits(mp, k) + d1)) * cm;
                    fraction[j][1][i] = ((real) ((int) getbits(mp, k) + d1)) * cm;
                    fraction[j][2][i] = ((real) ((int) getbits(mp, k) + d1)) * cm;
                }
                else {
                    static int *table[] = { 0, 0, 0, grp_3tab, 0, grp_5tab, 0, 0, 0, grp_9tab };
                    unsigned int idx, *tab, m = scale[x1];
                    idx = (unsigned int) getbits(mp, k);
                    tab = (unsigned int *) (table[d1] + idx + idx + idx);
                    fraction[j][0][i] = muls[*tab++][m];
                    fraction[j][1][i] = muls[*tab++][m];
                    fraction[j][2][i] = muls[*tab][m];
                }
                scale += 3;
            }
            else
                fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
        }
    }

    for (i = jsbound; i < sblimit; i++, alloc1 += (1 << step)) {
        step = alloc1->bits;
        bita++;         /* channel 1 and channel 2 bitalloc are the same */
        ba = *bita++;
        if (ba) {
            k = (alloc2 = alloc1 + ba)->bits;
            if ((d1 = alloc2->d) < 0) {
                real    cm;
                cm = muls[k][scale[x1 + 3]];
                fraction[1][0][i] = (fraction[0][0][i] = (real) ((int) getbits(mp, k) + d1)) * cm;
                fraction[1][1][i] = (fraction[0][1][i] = (real) ((int) getbits(mp, k) + d1)) * cm;
                fraction[1][2][i] = (fraction[0][2][i] = (real) ((int) getbits(mp, k) + d1)) * cm;
                cm = muls[k][scale[x1]];
                fraction[0][0][i] *= cm;
                fraction[0][1][i] *= cm;
                fraction[0][2][i] *= cm;
            }
            else {
                static int *table[] = { 0, 0, 0, grp_3tab, 0, grp_5tab, 0, 0, 0, grp_9tab };
                unsigned int idx, *tab, m1, m2;
                m1 = scale[x1];
                m2 = scale[x1 + 3];
                idx = (unsigned int) getbits(mp, k);
                tab = (unsigned int *) (table[d1] + idx + idx + idx);
                fraction[0][0][i] = muls[*tab][m1];
                fraction[1][0][i] = muls[*tab++][m2];
                fraction[0][1][i] = muls[*tab][m1];
                fraction[1][1][i] = muls[*tab++][m2];
                fraction[0][2][i] = muls[*tab][m1];
                fraction[1][2][i] = muls[*tab][m2];
            }
            scale += 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;
        }
/* 
   should we use individual scalefac for channel 2 or
   is the current way the right one , where we just copy channel 1 to
   channel 2 ?? 
   The current 'strange' thing is, that we throw away the scalefac
   values for the second channel ...!!
-> changed .. now we use the scalefac values of channel one !! 
*/
    }

/*  if(sblimit > (fr->down_sample_sblimit) ) */
/*    sblimit = fr->down_sample_sblimit; */

    for (i = sblimit; i < SBLIMIT; i++)
        for (j = 0; j < stereo; j++)
            fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;

}

static void
II_select_table(struct frame *fr)
{
    /* *INDENT-OFF* */
  static const int 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 } } };
    /* *INDENT-ON* */

    int     table, sblim;
    static const struct al_table2 *tables[5] = { alloc_0, alloc_1, alloc_2, alloc_3, alloc_4 };
    static const int sblims[5] = { 27, 30, 8, 12, 30 };

    if (fr->lsf)
        table = 4;
    else
        table = translate[fr->sampling_frequency][2 - fr->stereo][fr->bitrate_index];
    sblim = sblims[table];

    fr->alloc = (struct al_table2 const *) tables[table];
    fr->II_sblimit = sblim;
}


int
do_layer2(PMPSTR mp, unsigned char *pcm_sample, int *pcm_point)
/*int do_layer2(struct frame *fr,int outmode,struct audio_info_struct *ai) */
{
    int     clip = 0;
    int     i, j;
    real    fraction[2][4][SBLIMIT]; /* pick_table clears unused subbands */
    unsigned int bit_alloc[64];
    int     scale[192];
    struct frame *fr = &(mp->fr);
    int     stereo = fr->stereo;
    int     single = fr->single;

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

    if (stereo == 1 || single == 3)
        single = 0;

    II_step_one(mp, bit_alloc, scale, fr);

    for (i = 0; i < SCALE_BLOCK; i++) {
        II_step_two(mp, bit_alloc, fraction, scale, fr, i >> 2);
        for (j = 0; j < 3; j++) {
            if (single >= 0) {
                clip += synth_1to1_mono(mp, fraction[single][j], pcm_sample, pcm_point);
            }
            else {
                int     p1 = *pcm_point;
                clip += synth_1to1(mp, fraction[0][j], 0, pcm_sample, &p1);
                clip += synth_1to1(mp, fraction[1][j], 1, pcm_sample, pcm_point);
            }
        }
    }

    return clip;
}

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