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layer2.c

/* 
 * Mpeg Layer-2 audio decoder 
 * --------------------------
 * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README'
 *
 */

#include "mpg123.h"
#include "l2tables.h"
#include "getbits.h"

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 */

real mpg123_muls[27][64];     /* also used by layer 1 */

/* Used by the getbits macros */
static unsigned long rval;

void mpg123_init_layer2(void)
{
      static 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 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 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 = mpg123_muls[k];
            for (j = 3, i = 0; i < 63; i++, j--)
                  *table++ = m * pow(2.0, (double) j / 3.0);
            *table++ = 0.0;
      }
}

void II_step_one(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_table *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 > 0; i--, alloc1 += (1 << step))
            {
                  *bita++ = (char) mpg123_getbits(step = alloc1->bits);
                  *bita++ = (char) mpg123_getbits(step);
            }
            for (i = sblimit - jsbound; i > 0; i--, alloc1 += (1 << step))
            {
                  bita[0] = (char) mpg123_getbits(step = alloc1->bits);
                  bita[1] = bita[0];
                  bita += 2;
            }
            bita = bit_alloc;
            scfsi = scfsi_buf;
            for (i = sblimit2; i; i--)
                  if (*bita++)
                        *scfsi++ = (char) mpg123_getbits_fast(2);
      }
      else
            /* mono */
      {
            for (i = sblimit; i; i--, alloc1 += (1 << step))
                  *bita++ = (char) mpg123_getbits(step = alloc1->bits);
            bita = bit_alloc;
            scfsi = scfsi_buf;
            for (i = sblimit; i; i--)
                  if (*bita++)
                        *scfsi++ = (char) mpg123_getbits_fast(2);
      }

      bita = bit_alloc;
      scfsi = scfsi_buf;
      for (i = sblimit2; i; i--)
            if (*bita++)
                  switch (*scfsi++)
                  {
                        case 0:
                              *scale++ = mpg123_getbits_fast(6);
                              *scale++ = mpg123_getbits_fast(6);
                              *scale++ = mpg123_getbits_fast(6);
                              break;
                        case 1:
                              *scale++ = sc = mpg123_getbits_fast(6);
                              *scale++ = sc;
                              *scale++ = mpg123_getbits_fast(6);
                              break;
                        case 2:
                              *scale++ = sc = mpg123_getbits_fast(6);
                              *scale++ = sc;
                              *scale++ = sc;
                              break;
                        default:    /* case 3 */
                              *scale++ = mpg123_getbits_fast(6);
                              *scale++ = sc = mpg123_getbits_fast(6);
                              *scale++ = sc;
                              break;
                  }

}

void II_step_two(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_table *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++)
            {
                  if ((ba = *bita++))
                  {
                        k = (alloc2 = alloc1 + ba)->bits;
                        if ((d1 = alloc2->d) < 0)
                        {
                              real cm = mpg123_muls[k][scale[x1]];

                              fraction[j][0][i] = ((real) ((int) mpg123_getbits(k) + d1)) * cm;
                              fraction[j][1][i] = ((real) ((int) mpg123_getbits(k) + d1)) * cm;
                              fraction[j][2][i] = ((real) ((int) mpg123_getbits(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) mpg123_getbits(k);
                              tab = (unsigned int *) (table[d1] + idx + idx + idx);
                              fraction[j][0][i] = mpg123_muls[*tab++][m];
                              fraction[j][1][i] = mpg123_muls[*tab++][m];
                              fraction[j][2][i] = mpg123_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 */
            if ((ba = *bita++))
            {
                  k = (alloc2 = alloc1 + ba)->bits;
                  if ((d1 = alloc2->d) < 0)
                  {
                        real cm;

                        cm = mpg123_muls[k][scale[x1 + 3]];
                        fraction[1][0][i] = (fraction[0][0][i] = (real) ((int) mpg123_getbits(k) + d1)) * cm;
                        fraction[1][1][i] = (fraction[0][1][i] = (real) ((int) mpg123_getbits(k) + d1)) * cm;
                        fraction[1][2][i] = (fraction[0][2][i] = (real) ((int) mpg123_getbits(k) + d1)) * cm;
                        cm = mpg123_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) mpg123_getbits(k);
                        tab = (unsigned int *) (table[d1] + idx + idx + idx);
                        fraction[0][0][i] = mpg123_muls[*tab][m1];
                        fraction[1][0][i] = mpg123_muls[*tab++][m2];
                        fraction[0][1][i] = mpg123_muls[*tab][m1];
                        fraction[1][1][i] = mpg123_muls[*tab++][m2];
                        fraction[0][2][i] = mpg123_muls[*tab][m1];
                        fraction[1][2][i] = mpg123_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)
{
      static 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}}
      };

      int table, sblim;
      static struct al_table *tables[5] =
            {alloc_0, alloc_1, alloc_2, alloc_3, alloc_4};
      static 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 = tables[table];
      fr->II_sblimit = sblim;
}


int mpg123_do_layer2(struct frame *fr)
{
      int i, j;
      int stereo = fr->stereo;
      real fraction[2][4][SBLIMIT]; /* pick_table clears unused subbands */
      unsigned int bit_alloc[64];
      int scale[192];
      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 (fr->jsbound > fr->II_sblimit)
            fr->jsbound = fr->II_sblimit;

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

      II_step_one(bit_alloc, scale, fr);

      for (i = 0; i < SCALE_BLOCK; i++)
      {
            II_step_two(bit_alloc, fraction, scale, fr, i >> 2);
            for (j = 0; j < 3; j++)
            {
                  if (single >= 0)
                  {
                        (fr->synth_mono) (fraction[single][j], mpg123_pcm_sample, &mpg123_pcm_point);
                  }
                  else
                  {
                        int p1 = mpg123_pcm_point;

                        (fr->synth) (fraction[0][j], 0, mpg123_pcm_sample, &p1);
                        (fr->synth) (fraction[1][j], 1, mpg123_pcm_sample, &mpg123_pcm_point);
                  }

                  /*    if(mpg123_pcm_point >= audiobufsize)
                     audio_flush(outmode,ai); */
            }
      }
/***
      if (mpg123_info->output_audio)
      {

            mpg123_ip.add_vis_pcm(mpg123_ip.output->written_time(), mpg123_cfg.resolution == 16 ? FMT_S16_NE : FMT_U8,
                              mpg123_cfg.channels == 2 ? fr->stereo : 1, mpg123_pcm_point, mpg123_pcm_sample);

            while (mpg123_ip.output->buffer_free() < mpg123_pcm_point && mpg123_info->going && mpg123_info->jump_to_time == -1)
                  xmms_usleep(10000);
            if (mpg123_info->going && mpg123_info->jump_to_time == -1)
                  mpg123_ip.output->write_audio(mpg123_pcm_sample, mpg123_pcm_point);

      }
***/
      mpg123_pcm_point = 0;

      return 1;
}

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