mpv/mp3lib/layer3.c

/*
 * Modified for use with MPlayer, for details see the changelog at
 * http://svn.mplayerhq.hu/mplayer/trunk/
 * $Id$
 */

/* 
 * Mpeg Layer-3 audio decoder 
 * --------------------------
 * copyright (c) 1995-1999 by Michael Hipp.
 * All rights reserved. See also 'README'
 *
 * Optimize-TODO: put short bands into the band-field without the stride 
 *                of 3 reals
 * Length-optimze: unify long and short band code where it is possible
 */ 

#if 0
#define L3_DEBUG 1
#endif

#if 0
#define CUT_HF
#endif

# define REAL_MUL(x, y)		((x) * (y))

static real ispow[8207];
static real aa_ca[8],aa_cs[8];
static real COS1[12][6];
static real win[4][36];
static real win1[4][36];
static real gainpow2[256+118+4];

/* non static for external 3dnow functions */
real   COS9[9];
static real COS6_1,COS6_2;
real   tfcos36[9];

static real tfcos12[3];
#define NEW_DCT9
#ifdef NEW_DCT9
static real cos9[3],cos18[3];
#endif

struct bandInfoStruct {
  int longIdx[23];
  int longDiff[22];
  int shortIdx[14];
  int shortDiff[13];
};

static int longLimit[9][23];
static int shortLimit[9][14];

static struct bandInfoStruct bandInfo[9] = { 

/* MPEG 1.0 */
 { {0,4,8,12,16,20,24,30,36,44,52,62,74, 90,110,134,162,196,238,288,342,418,576},
   {4,4,4,4,4,4,6,6,8, 8,10,12,16,20,24,28,34,42,50,54, 76,158},
   {0,4*3,8*3,12*3,16*3,22*3,30*3,40*3,52*3,66*3, 84*3,106*3,136*3,192*3},
   {4,4,4,4,6,8,10,12,14,18,22,30,56} } ,

 { {0,4,8,12,16,20,24,30,36,42,50,60,72, 88,106,128,156,190,230,276,330,384,576},
   {4,4,4,4,4,4,6,6,6, 8,10,12,16,18,22,28,34,40,46,54, 54,192},
   {0,4*3,8*3,12*3,16*3,22*3,28*3,38*3,50*3,64*3, 80*3,100*3,126*3,192*3},
   {4,4,4,4,6,6,10,12,14,16,20,26,66} } ,

 { {0,4,8,12,16,20,24,30,36,44,54,66,82,102,126,156,194,240,296,364,448,550,576} ,
   {4,4,4,4,4,4,6,6,8,10,12,16,20,24,30,38,46,56,68,84,102, 26} ,
   {0,4*3,8*3,12*3,16*3,22*3,30*3,42*3,58*3,78*3,104*3,138*3,180*3,192*3} ,
   {4,4,4,4,6,8,12,16,20,26,34,42,12} }  ,

/* MPEG 2.0 */
 { {0,6,12,18,24,30,36,44,54,66,80,96,116,140,168,200,238,284,336,396,464,522,576},
   {6,6,6,6,6,6,8,10,12,14,16,20,24,28,32,38,46,52,60,68,58,54 } ,
   {0,4*3,8*3,12*3,18*3,24*3,32*3,42*3,56*3,74*3,100*3,132*3,174*3,192*3} ,
   {4,4,4,6,6,8,10,14,18,26,32,42,18 } } ,
/* changed 19th value fropm 330 to 332 */
 { {0,6,12,18,24,30,36,44,54,66,80,96,114,136,162,194,232,278,332,394,464,540,576},
   {6,6,6,6,6,6,8,10,12,14,16,18,22,26,32,38,46,54,62,70,76,36 } ,
   {0,4*3,8*3,12*3,18*3,26*3,36*3,48*3,62*3,80*3,104*3,136*3,180*3,192*3} ,
   {4,4,4,6,8,10,12,14,18,24,32,44,12 } } ,

 { {0,6,12,18,24,30,36,44,54,66,80,96,116,140,168,200,238,284,336,396,464,522,576},
   {6,6,6,6,6,6,8,10,12,14,16,20,24,28,32,38,46,52,60,68,58,54 },
   {0,4*3,8*3,12*3,18*3,26*3,36*3,48*3,62*3,80*3,104*3,134*3,174*3,192*3},
   {4,4,4,6,8,10,12,14,18,24,30,40,18 } } ,
/* MPEG 2.5 */
 { {0,6,12,18,24,30,36,44,54,66,80,96,116,140,168,200,238,284,336,396,464,522,576} ,
   {6,6,6,6,6,6,8,10,12,14,16,20,24,28,32,38,46,52,60,68,58,54},
   {0,12,24,36,54,78,108,144,186,240,312,402,522,576},
   {4,4,4,6,8,10,12,14,18,24,30,40,18} },
 { {0,6,12,18,24,30,36,44,54,66,80,96,116,140,168,200,238,284,336,396,464,522,576} ,
   {6,6,6,6,6,6,8,10,12,14,16,20,24,28,32,38,46,52,60,68,58,54},
   {0,12,24,36,54,78,108,144,186,240,312,402,522,576},
   {4,4,4,6,8,10,12,14,18,24,30,40,18} },
 { {0,12,24,36,48,60,72,88,108,132,160,192,232,280,336,400,476,566,568,570,572,574,576},
   {12,12,12,12,12,12,16,20,24,28,32,40,48,56,64,76,90,2,2,2,2,2},
   {0, 24, 48, 72,108,156,216,288,372,480,486,492,498,576},
   {8,8,8,12,16,20,24,28,36,2,2,2,26} } ,
};

static int mapbuf0[9][152];
static int mapbuf1[9][156];
static int mapbuf2[9][44];
static int *map[9][3];
static int *mapend[9][3];

static unsigned int n_slen2[512]; /* MPEG 2.0 slen for 'normal' mode */
static unsigned int i_slen2[256]; /* MPEG 2.0 slen for intensity stereo */

static real tan1_1[16],tan2_1[16],tan1_2[16],tan2_2[16];
static real pow1_1[2][16],pow2_1[2][16],pow1_2[2][16],pow2_2[2][16];

/*
 * init tables for layer-3
 */
static void init_layer3(int down_sample_sblimit)
{
  int i,j,k,l;

  for(i=-256;i<118+4;i++)
  {
    if(_has_mmx)
      gainpow2[i+256] = 16384.0 * pow((double)2.0,-0.25 * (double) (i+210) );
    else
      gainpow2[i+256] = pow((double)2.0,-0.25 * (double) (i+210) );
  }
  for(i=0;i<8207;i++)
    ispow[i] = pow((double)i,(double)4.0/3.0);

  for (i=0;i<8;i++)
  {
    static double Ci[8]={-0.6,-0.535,-0.33,-0.185,-0.095,-0.041,-0.0142,-0.0037};
    double sq=sqrt(1.0+Ci[i]*Ci[i]);
    aa_cs[i] = 1.0/sq;
    aa_ca[i] = Ci[i]/sq;
  }

  for(i=0;i<18;i++)
  {
    win[0][i]    = win[1][i]    = 0.5 * sin( M_PI / 72.0 * (double) (2*(i+0) +1) ) / cos ( M_PI * (double) (2*(i+0) +19) / 72.0 );
    win[0][i+18] = win[3][i+18] = 0.5 * sin( M_PI / 72.0 * (double) (2*(i+18)+1) ) / cos ( M_PI * (double) (2*(i+18)+19) / 72.0 );
  }
  for(i=0;i<6;i++)
  {
    win[1][i+18] = 0.5 / cos ( M_PI * (double) (2*(i+18)+19) / 72.0 );
    win[3][i+12] = 0.5 / cos ( M_PI * (double) (2*(i+12)+19) / 72.0 );
    win[1][i+24] = 0.5 * sin( M_PI / 24.0 * (double) (2*i+13) ) / cos ( M_PI * (double) (2*(i+24)+19) / 72.0 );
    win[1][i+30] = win[3][i] = 0.0;
    win[3][i+6 ] = 0.5 * sin( M_PI / 24.0 * (double) (2*i+1) )  / cos ( M_PI * (double) (2*(i+6 )+19) / 72.0 );
  }

  for(i=0;i<9;i++)
    COS9[i] = cos( M_PI / 18.0 * (double) i);

  for(i=0;i<9;i++)
    tfcos36[i] = 0.5 / cos ( M_PI * (double) (i*2+1) / 36.0 );
  for(i=0;i<3;i++)
    tfcos12[i] = 0.5 / cos ( M_PI * (double) (i*2+1) / 12.0 );

  COS6_1 = cos( M_PI / 6.0 * (double) 1);
  COS6_2 = cos( M_PI / 6.0 * (double) 2);

#ifdef NEW_DCT9
  cos9[0] = cos(1.0*M_PI/9.0);
  cos9[1] = cos(5.0*M_PI/9.0);
  cos9[2] = cos(7.0*M_PI/9.0);
  cos18[0] = cos(1.0*M_PI/18.0);
  cos18[1] = cos(11.0*M_PI/18.0);
  cos18[2] = cos(13.0*M_PI/18.0);
#endif

  for(i=0;i<12;i++)
  {
    win[2][i]  = 0.5 * sin( M_PI / 24.0 * (double) (2*i+1) ) / cos ( M_PI * (double) (2*i+7) / 24.0 );
    for(j=0;j<6;j++)
      COS1[i][j] = cos( M_PI / 24.0 * (double) ((2*i+7)*(2*j+1)) );
  }

  for(j=0;j<4;j++) {
    static int len[4] = { 36,36,12,36 };
    for(i=0;i<len[j];i+=2)
      win1[j][i] = + win[j][i];
    for(i=1;i<len[j];i+=2)
      win1[j][i] = - win[j][i];
  }

  for(i=0;i<16;i++)
  {
    double t = tan( (double) i * M_PI / 12.0 );
    tan1_1[i] = t / (1.0+t);
    tan2_1[i] = 1.0 / (1.0 + t);
    tan1_2[i] = M_SQRT2 * t / (1.0+t);
    tan2_2[i] = M_SQRT2 / (1.0 + t);

    for(j=0;j<2;j++) {
      double base = pow(2.0,-0.25*(j+1.0));
      double p1=1.0,p2=1.0;
      if(i > 0) {
        if( i & 1 )
          p1 = pow(base,(i+1.0)*0.5);
        else
          p2 = pow(base,i*0.5);
      }
      pow1_1[j][i] = p1;
      pow2_1[j][i] = p2;
      pow1_2[j][i] = M_SQRT2 * p1;
      pow2_2[j][i] = M_SQRT2 * p2;
    }
  }

  for(j=0;j<9;j++)
  {
   struct bandInfoStruct *bi = &bandInfo[j];
   int *mp;
   int cb,lwin;
   int *bdf;

   mp = map[j][0] = mapbuf0[j];
   bdf = bi->longDiff;
   for(i=0,cb = 0; cb < 8 ; cb++,i+=*bdf++) {
     *mp++ = (*bdf) >> 1;
     *mp++ = i;
     *mp++ = 3;
     *mp++ = cb;
   }
   bdf = bi->shortDiff+3;
   for(cb=3;cb<13;cb++) {
     int l = (*bdf++) >> 1;
     for(lwin=0;lwin<3;lwin++) {
       *mp++ = l;
       *mp++ = i + lwin;
       *mp++ = lwin;
       *mp++ = cb;
     }
     i += 6*l;
   }
   mapend[j][0] = mp;

   mp = map[j][1] = mapbuf1[j];
   bdf = bi->shortDiff+0;
   for(i=0,cb=0;cb<13;cb++) {
     int l = (*bdf++) >> 1;
     for(lwin=0;lwin<3;lwin++) {
       *mp++ = l;
       *mp++ = i + lwin;
       *mp++ = lwin;
       *mp++ = cb;
     }
     i += 6*l;
   }
   mapend[j][1] = mp;

   mp = map[j][2] = mapbuf2[j];
   bdf = bi->longDiff;
   for(cb = 0; cb < 22 ; cb++) {
     *mp++ = (*bdf++) >> 1;
     *mp++ = cb;
   }
   mapend[j][2] = mp;

  }

  for(j=0;j<9;j++) {
    for(i=0;i<23;i++) {
      longLimit[j][i] = (bandInfo[j].longIdx[i] - 1 + 8) / 18 + 1;
      if(longLimit[j][i] > (down_sample_sblimit) )
        longLimit[j][i] = down_sample_sblimit;
    }
    for(i=0;i<14;i++) {
      shortLimit[j][i] = (bandInfo[j].shortIdx[i] - 1) / 18 + 1;
      if(shortLimit[j][i] > (down_sample_sblimit) )
        shortLimit[j][i] = down_sample_sblimit;
    }
  }

  for(i=0;i<5;i++) {
    for(j=0;j<6;j++) {
      for(k=0;k<6;k++) {
        int n = k + j * 6 + i * 36;
        i_slen2[n] = i|(j<<3)|(k<<6)|(3<<12);
      }
    }
  }
  for(i=0;i<4;i++) {
    for(j=0;j<4;j++) {
      for(k=0;k<4;k++) {
        int n = k + j * 4 + i * 16;
        i_slen2[n+180] = i|(j<<3)|(k<<6)|(4<<12);
      }
    }
  }
  for(i=0;i<4;i++) {
    for(j=0;j<3;j++) {
      int n = j + i * 3;
      i_slen2[n+244] = i|(j<<3) | (5<<12);
      n_slen2[n+500] = i|(j<<3) | (2<<12) | (1<<15);
    }
  }

  for(i=0;i<5;i++) {
    for(j=0;j<5;j++) {
      for(k=0;k<4;k++) {
        for(l=0;l<4;l++) {
          int n = l + k * 4 + j * 16 + i * 80;
          n_slen2[n] = i|(j<<3)|(k<<6)|(l<<9)|(0<<12);
        }
      }
    }
  }
  for(i=0;i<5;i++) {
    for(j=0;j<5;j++) {
      for(k=0;k<4;k++) {
        int n = k + j * 4 + i * 20;
        n_slen2[n+400] = i|(j<<3)|(k<<6)|(1<<12);
      }
    }
  }
}

/*
 * read additional side information (for MPEG 1 and MPEG 2)
 */
static int III_get_side_info(struct III_sideinfo *si,int stereo,
 int ms_stereo,int sfreq,int single,int lsf)
{
   int ch, gr;
   int powdiff = (single == 3) ? 4 : 0;

   static const int tabs[2][5] = { { 2,9,5,3,4 } , { 1,8,1,2,9 } };
   const int *tab = tabs[lsf];
   
   si->main_data_begin = getbits(tab[1]);
   if (stereo == 1)
     si->private_bits = getbits_fast(tab[2]);
   else 
     si->private_bits = getbits_fast(tab[3]);

   if(!lsf) {
     for (ch=0; ch<stereo; ch++) {
         si->ch[ch].gr[0].scfsi = -1;
         si->ch[ch].gr[1].scfsi = getbits_fast(4);
     }
   }

   for (gr=0; gr<tab[0]; gr++) {
     for (ch=0; ch<stereo; ch++) {
       register struct gr_info_s *gr_info = &(si->ch[ch].gr[gr]);

       gr_info->part2_3_length = getbits(12);
       gr_info->big_values = getbits(9);
       if(gr_info->big_values > 288) {
            fprintf(stderr,"big_values too large!\n");
          gr_info->big_values = 288;
       }
       gr_info->pow2gain = gainpow2+256 - getbits_fast(8) + powdiff;
       if(ms_stereo)
         gr_info->pow2gain += 2;
       gr_info->scalefac_compress = getbits(tab[4]);

       if(get1bit()) { /* window switch flag  */
         int i;
#ifdef L3_DEBUG
if(2*gr_info->big_values > bandInfo[sfreq].shortIdx[12])
  fprintf(stderr,"L3: BigValues too large, doesn't make sense %d %d\n",2*gr_info->big_values,bandInfo[sfreq].shortIdx[12]);
#endif

         gr_info->block_type       = getbits_fast(2);
         gr_info->mixed_block_flag = get1bit();
         gr_info->table_select[0]  = getbits_fast(5);
         gr_info->table_select[1]  = getbits_fast(5);
         /*
          * table_select[2] not needed, because there is no region2,
          * but to satisfy some verifications tools we set it either.
          */
         gr_info->table_select[2] = 0;
         for(i=0;i<3;i++)
           gr_info->full_gain[i] = gr_info->pow2gain + (getbits_fast(3)<<3);

         if(gr_info->block_type == 0) {
             fprintf(stderr,"Blocktype == 0 and window-switching == 1 not allowed.\n");
           return 0;
         }
      
         /* region_count/start parameters are implicit in this case. */       
         if(!lsf || gr_info->block_type == 2)
           gr_info->region1start = 36>>1;
         else {
/* check this again for 2.5 and sfreq=8 */
           if(sfreq == 8)
             gr_info->region1start = 108>>1;
           else
             gr_info->region1start = 54>>1;
         }
         gr_info->region2start = 576>>1;
       }
       else {
         int i,r0c,r1c;
#ifdef L3_DEBUG
if(2*gr_info->big_values > bandInfo[sfreq].longIdx[21])
  fprintf(stderr,"L3: BigValues too large, doesn't make sense %d %d\n",2*gr_info->big_values,bandInfo[sfreq].longIdx[21]);
#endif
         for (i=0; i<3; i++)
           gr_info->table_select[i] = getbits_fast(5);
         r0c = getbits_fast(4);
         r1c = getbits_fast(3);
         gr_info->region1start = bandInfo[sfreq].longIdx[r0c+1] >> 1 ;
         if(r0c + r1c + 2 > 22)
           gr_info->region2start = 576>>1;
         else
           gr_info->region2start = bandInfo[sfreq].longIdx[r0c+1+r1c+1] >> 1;
         gr_info->block_type = 0;
         gr_info->mixed_block_flag = 0;
       }
       if(!lsf)
         gr_info->preflag = get1bit();
       gr_info->scalefac_scale = get1bit();
       gr_info->count1table_select = get1bit();
     }
   }

   return !0;
}

/*
 * read scalefactors
 */
static int III_get_scale_factors_1(int *scf,struct gr_info_s *gr_info)
{
   static const unsigned char slen[2][16] = {
     {0, 0, 0, 0, 3, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4},
     {0, 1, 2, 3, 0, 1, 2, 3, 1, 2, 3, 1, 2, 3, 2, 3}
   };
   int numbits;
   int num0 = slen[0][gr_info->scalefac_compress];
   int num1 = slen[1][gr_info->scalefac_compress];

    if (gr_info->block_type == 2) {
      int i=18;
      numbits = (num0 + num1) * 18;

      if (gr_info->mixed_block_flag) {
         for (i=8;i;i--)
           *scf++ = getbits_fast(num0);
         i = 9;
         numbits -= num0; /* num0 * 17 + num1 * 18 */
      }

      for (;i;i--)
        *scf++ = getbits_fast(num0);
      for (i = 18; i; i--)
        *scf++ = getbits_fast(num1);
      *scf++ = 0; *scf++ = 0; *scf++ = 0; /* short[13][0..2] = 0 */
    }
    else {
      int i;
      int scfsi = gr_info->scfsi;

      if(scfsi < 0) { /* scfsi < 0 => granule == 0 */
         for(i=11;i;i--)
           *scf++ = getbits_fast(num0);
         for(i=10;i;i--)
           *scf++ = getbits_fast(num1);
         numbits = (num0 + num1) * 10 + num0;
         *scf++ = 0;
      }
      else {
        numbits = 0;
        if(!(scfsi & 0x8)) {
          for (i=0;i<6;i++)
            *scf++ = getbits_fast(num0);
          numbits += num0 * 6;
        }
        else {
          scf += 6; 
        }

        if(!(scfsi & 0x4)) {
          for (i=0;i<5;i++)
            *scf++ = getbits_fast(num0);
          numbits += num0 * 5;
        }
        else {
          scf += 5;
        }

        if(!(scfsi & 0x2)) {
          for(i=0;i<5;i++)
            *scf++ = getbits_fast(num1);
          numbits += num1 * 5;
        }
        else {
          scf += 5; 
        }

        if(!(scfsi & 0x1)) {
          for (i=0;i<5;i++)
            *scf++ = getbits_fast(num1);
          numbits += num1 * 5;
        }
        else {
           scf += 5;
        }
        *scf++ = 0;  /* no l[21] in original sources */
      }
    }
    return numbits;
}

static int III_get_scale_factors_2(int *scf,struct gr_info_s *gr_info,int i_stereo)
{
  unsigned char *pnt;
  int i,j;
  unsigned int slen;
  int n = 0;
  int numbits = 0;

  static unsigned char stab[3][6][4] = {
   { { 6, 5, 5,5 } , { 6, 5, 7,3 } , { 11,10,0,0} ,
     { 7, 7, 7,0 } , { 6, 6, 6,3 } , {  8, 8,5,0} } ,
   { { 9, 9, 9,9 } , { 9, 9,12,6 } , { 18,18,0,0} ,
     {12,12,12,0 } , {12, 9, 9,6 } , { 15,12,9,0} } ,
   { { 6, 9, 9,9 } , { 6, 9,12,6 } , { 15,18,0,0} ,
     { 6,15,12,0 } , { 6,12, 9,6 } , {  6,18,9,0} } }; 

  if(i_stereo) /* i_stereo AND second channel -> do_layer3() checks this */
    slen = i_slen2[gr_info->scalefac_compress>>1];
  else
    slen = n_slen2[gr_info->scalefac_compress];

  gr_info->preflag = (slen>>15) & 0x1;

  n = 0;  
  if( gr_info->block_type == 2 ) {
    n++;
    if(gr_info->mixed_block_flag) n++;
  }

  pnt = stab[n][(slen>>12)&0x7];

  for(i=0;i<4;i++) {
    int num = slen & 0x7;
    slen >>= 3;
    if(num) {
      for(j=0;j<(int)(pnt[i]);j++) *scf++ = getbits_fast(num);
      numbits += pnt[i] * num;
    }
    else {
      for(j=0;j<(int)(pnt[i]);j++) *scf++ = 0;
    }
  }
  
  n = (n << 1) + 1;
  for(i=0;i<n;i++) *scf++ = 0;

  return numbits;
}

static int pretab1[22] = {0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,2,2,3,3,3,2,0};
static int pretab2[22] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};

#define getbitoffset() ((-bitindex)&0x7)
#define getbyte()      (*wordpointer++)

/*
 * Dequantize samples (includes huffman decoding)
 */
/* 24 is enough because tab13 has max. a 19 bit huffvector */
#define BITSHIFT ((sizeof(long)-1)*8)
#define REFRESH_MASK \
  while(num < BITSHIFT) { \
    mask |= ((unsigned long)getbyte())<<(BITSHIFT-num); \
    num += 8; \
    part2remain -= 8; }

static int III_dequantize_sample(real xr[SBLIMIT][SSLIMIT],int *scf,
   struct gr_info_s *gr_info,int sfreq,int part2bits)
{
  int shift = 1 + gr_info->scalefac_scale;
  real *xrpnt = (real *) xr;
  int l[3],l3;
  int part2remain = gr_info->part2_3_length - part2bits;
  int *me;

  int num=getbitoffset();
  long mask;
  /* we must split this, because for num==0 the shift is undefined if you do it in one step */
  mask  = ((unsigned long) getbits(num))<<BITSHIFT;
  mask <<= 8-num;
  part2remain -= num;

  {
    int bv       = gr_info->big_values;
    int region1  = gr_info->region1start;
    int region2  = gr_info->region2start;

    l3 = ((576>>1)-bv)>>1;   
/*
 * we may lose the 'odd' bit here !! 
 * check this later again 
 */
    if(bv <= region1) {
      l[0] = bv; l[1] = l[2] = 0;
    }
    else {
      l[0] = region1;
      if(bv <= region2) {
        l[1] = bv - l[0];  l[2] = 0;
      }
      else {
        l[1] = region2 - l[0]; l[2] = bv - region2;
      }
    }
  }
 
  if(gr_info->block_type == 2) {
    /*
     * decoding with short or mixed mode BandIndex table 
     */
    int i,max[4];
    int step=0,lwin=3,cb=0;
    register real v = 0.0;
    register int *m,mc;

    if(gr_info->mixed_block_flag) {
      max[3] = -1;
      max[0] = max[1] = max[2] = 2;
      m = map[sfreq][0];
      me = mapend[sfreq][0];
    }
    else {
      max[0] = max[1] = max[2] = max[3] = -1;
      /* max[3] not really needed in this case */
      m = map[sfreq][1];
      me = mapend[sfreq][1];
    }

    mc = 0;
    for(i=0;i<2;i++) {
      int lp = l[i];
      struct newhuff *h = ht+gr_info->table_select[i];
      for(;lp;lp--,mc--) {
        register int x,y;
        if( (!mc) ) {
          mc    = *m++;
          xrpnt = ((real *) xr) + (*m++);
          lwin  = *m++;
          cb    = *m++;
          if(lwin == 3) {
            v = gr_info->pow2gain[(*scf++) << shift];
            step = 1;
          }
          else {
            v = gr_info->full_gain[lwin][(*scf++) << shift];
            step = 3;
          }
        }
        {
          register short *val = h->table;
          REFRESH_MASK;
          while((y=*val++)<0) {
            if (mask < 0)
              val -= y;
            num--;
            mask <<= 1;
          }
          x = y >> 4;
          y &= 0xf;
        }
        if(x == 15 && h->linbits) {
          max[lwin] = cb;
          REFRESH_MASK;
          x += ((unsigned long) mask) >> (BITSHIFT+8-h->linbits);
          num -= h->linbits+1;
          mask <<= h->linbits;
          if(mask < 0)
            *xrpnt = REAL_MUL(-ispow[x], v);
          else
            *xrpnt = REAL_MUL(ispow[x], v);
          mask <<= 1;
        }
        else if(x) {
          max[lwin] = cb;
          if(mask < 0)
            *xrpnt = REAL_MUL(-ispow[x], v);
          else
            *xrpnt = REAL_MUL(ispow[x], v);
          num--;
          mask <<= 1;
        }
        else
          *xrpnt = 0.0;
        xrpnt += step;
        if(y == 15 && h->linbits) {
          max[lwin] = cb;
          REFRESH_MASK;
          y += ((unsigned long) mask) >> (BITSHIFT+8-h->linbits);
          num -= h->linbits+1;
          mask <<= h->linbits;
          if(mask < 0)
            *xrpnt = REAL_MUL(-ispow[y], v);
          else
            *xrpnt = REAL_MUL(ispow[y], v);
          mask <<= 1;
        }
        else if(y) {
          max[lwin] = cb;
          if(mask < 0)
            *xrpnt = REAL_MUL(-ispow[y], v);
          else
            *xrpnt = REAL_MUL(ispow[y], v);
          num--;
          mask <<= 1;
        }
        else
          *xrpnt = 0.0;
        xrpnt += step;
      }
    }

    for(;l3 && (part2remain+num > 0);l3--) {
      struct newhuff *h = htc+gr_info->count1table_select;
      register short *val = h->table,a;

      REFRESH_MASK;
      while((a=*val++)<0) {
        if (mask < 0)
          val -= a;
        num--;
        mask <<= 1;
      }
      if(part2remain+num <= 0) {
	num -= part2remain+num;
	break;
      }

      for(i=0;i<4;i++) {
        if(!(i & 1)) {
          if(!mc) {
            mc = *m++;
            xrpnt = ((real *) xr) + (*m++);
            lwin = *m++;
            cb = *m++;
            if(lwin == 3) {
              v = gr_info->pow2gain[(*scf++) << shift];
              step = 1;
            }
            else {
              v = gr_info->full_gain[lwin][(*scf++) << shift];
              step = 3;
            }
          }
          mc--;
        }
        if( (a & (0x8>>i)) ) {
          max[lwin] = cb;
          if(part2remain+num <= 0) {
            break;
          }
          if(mask < 0) 
            *xrpnt = -v;
          else
            *xrpnt = v;
          num--;
          mask <<= 1;
        }
        else
          *xrpnt = 0.0;
        xrpnt += step;
      }
    }

    if(lwin < 3) { /* short band? */
      while(1) {
        for(;mc > 0;mc--) {
          *xrpnt = 0.0; xrpnt += 3; /* short band -> step=3 */
          *xrpnt = 0.0; xrpnt += 3;
        }
        if(m >= me)
          break;
        mc    = *m++;
        xrpnt = ((real *) xr) + *m++;
        if(*m++ == 0)
          break; /* optimize: field will be set to zero at the end of the function */
        m++; /* cb */
      }
    }

    gr_info->maxband[0] = max[0]+1;
    gr_info->maxband[1] = max[1]+1;
    gr_info->maxband[2] = max[2]+1;
    gr_info->maxbandl = max[3]+1;

    {
      int rmax = max[0] > max[1] ? max[0] : max[1];
      rmax = (rmax > max[2] ? rmax : max[2]) + 1;
      gr_info->maxb = rmax ? shortLimit[sfreq][rmax] : longLimit[sfreq][max[3]+1];
    }

  }
  else {
    /*
     * decoding with 'long' BandIndex table (block_type != 2)
     */
    int *pretab = gr_info->preflag ? pretab1 : pretab2;
    int i,max = -1;
    int cb = 0;
    int *m = map[sfreq][2];
    register real v = 0.0;
    int mc = 0;

    /*
     * long hash table values
     */
    for(i=0;i<3;i++) {
      int lp = l[i];
      struct newhuff *h = ht+gr_info->table_select[i];

      for(;lp;lp--,mc--) {
        int x,y;

        if(!mc) {
          mc = *m++;
          cb = *m++;
#ifdef CUT_HF
          if(cb == 21) {
            fprintf(stderr,"c");
            v = 0.0;
          }
          else
#endif
            v = gr_info->pow2gain[((*scf++) + (*pretab++)) << shift];

        }
        {
          register short *val = h->table;
          REFRESH_MASK;
          while((y=*val++)<0) {
            if (mask < 0)
              val -= y;
            num--;
            mask <<= 1;
          }
          x = y >> 4;
          y &= 0xf;
        }

        if (x == 15 && h->linbits) {
          max = cb;
	  REFRESH_MASK;
          x += ((unsigned long) mask) >> (BITSHIFT+8-h->linbits);
          num -= h->linbits+1;
          mask <<= h->linbits;
          if(mask < 0)
            *xrpnt++ = REAL_MUL(-ispow[x], v);
          else
            *xrpnt++ = REAL_MUL(ispow[x], v);
          mask <<= 1;
        }
        else if(x) {
          max = cb;
          if(mask < 0)
            *xrpnt++ = REAL_MUL(-ispow[x], v);
          else
            *xrpnt++ = REAL_MUL(ispow[x], v);
          num--;
          mask <<= 1;
        }
        else
          *xrpnt++ = 0.0;

        if (y == 15 && h->linbits) {
          max = cb;
	  REFRESH_MASK;
          y += ((unsigned long) mask) >> (BITSHIFT+8-h->linbits);
          num -= h->linbits+1;
          mask <<= h->linbits;
          if(mask < 0)
            *xrpnt++ = REAL_MUL(-ispow[y], v);
          else
            *xrpnt++ = REAL_MUL(ispow[y], v);
          mask <<= 1;
        }
        else if(y) {
          max = cb;
          if(mask < 0)
            *xrpnt++ = REAL_MUL(-ispow[y], v);
          else
            *xrpnt++ = REAL_MUL(ispow[y], v);
          num--;
          mask <<= 1;
        }
        else
          *xrpnt++ = 0.0;
      }
    }

    /*
     * short (count1table) values
     */
    for(;l3 && (part2remain+num > 0);l3--) {
      struct newhuff *h = htc+gr_info->count1table_select;
      register short *val = h->table,a;

      REFRESH_MASK;
      while((a=*val++)<0) {
        if (mask < 0)
          val -= a;
        num--;
        mask <<= 1;
      }
      if(part2remain+num <= 0) {
	num -= part2remain+num;
        break;
      }

      for(i=0;i<4;i++) {
        if(!(i & 1)) {
          if(!mc) {
            mc = *m++;
            cb = *m++;
#ifdef CUT_HF
            if(cb == 21) { 
              fprintf(stderr,"c");
              v = 0.0;
            }
            else
#endif
              v = gr_info->pow2gain[((*scf++) + (*pretab++)) << shift];
          }
          mc--;
        }
        if ( (a & (0x8>>i)) ) {
          max = cb;
          if(part2remain+num <= 0) {
            break;
          }
          if(mask < 0)
            *xrpnt++ = -v;
          else
            *xrpnt++ = v;
          num--;
          mask <<= 1;
        }
        else
          *xrpnt++ = 0.0;
      }
    }

    gr_info->maxbandl = max+1;
    gr_info->maxb = longLimit[sfreq][gr_info->maxbandl];
  }

  part2remain += num;
//  backbits(num);
  bitindex -= num; wordpointer += (bitindex>>3); bitindex &= 0x7;
  num = 0;

  while(xrpnt < &xr[SBLIMIT][0]) 
    *xrpnt++ = 0.0;

  while( part2remain > 16 ) {
    getbits(16); /* Dismiss stuffing Bits */
    part2remain -= 16;
  }
  if(part2remain > 0)
    getbits(part2remain);
  else if(part2remain < 0) {
      fprintf(stderr,"mpg123: Can't rewind stream by %d bits!\n",-part2remain);
    return 1; /* -> error */
  }
  return 0;
}




/* 
 * III_stereo: calculate real channel values for Joint-I-Stereo-mode
 */
static void III_i_stereo(real xr_buf[2][SBLIMIT][SSLIMIT],int *scalefac,
   struct gr_info_s *gr_info,int sfreq,int ms_stereo,int lsf)
{
      real (*xr)[SBLIMIT*SSLIMIT] = (real (*)[SBLIMIT*SSLIMIT] ) xr_buf;
      struct bandInfoStruct *bi = &bandInfo[sfreq];

      const real *tab1,*tab2;

      int tab;
      static const real *tabs[3][2][2] = { 
         { { tan1_1,tan2_1 }     , { tan1_2,tan2_2 } },
         { { pow1_1[0],pow2_1[0] } , { pow1_2[0],pow2_2[0] } } ,
         { { pow1_1[1],pow2_1[1] } , { pow1_2[1],pow2_2[1] } } 
      };

      tab = lsf + (gr_info->scalefac_compress & lsf);
      tab1 = tabs[tab][ms_stereo][0];
      tab2 = tabs[tab][ms_stereo][1];
#if 0
      if(lsf) {
        int p = gr_info->scalefac_compress & 0x1;
	if(ms_stereo) {
          tab1 = pow1_2[p]; tab2 = pow2_2[p];
        }
        else {
          tab1 = pow1_1[p]; tab2 = pow2_1[p];
        }
      }
      else {
        if(ms_stereo) {
          tab1 = tan1_2; tab2 = tan2_2;
        }
        else {
          tab1 = tan1_1; tab2 = tan2_1;
        }
      }
#endif

//      printf("III_i_st: tab1=%p tab2=%p tab=%d ms=%d  \n", tab1, tab2, tab, ms_stereo);

      if (gr_info->block_type == 2) {
         int lwin,do_l = 0;
         if( gr_info->mixed_block_flag )
           do_l = 1;

         for (lwin=0;lwin<3;lwin++) { /* process each window */
             /* get first band with zero values */
           int is_p,sb,idx,sfb = gr_info->maxband[lwin];  /* sfb is minimal 3 for mixed mode */
           if(sfb > 3)
             do_l = 0;

           for(;sfb<12;sfb++) {
             is_p = scalefac[sfb*3+lwin-gr_info->mixed_block_flag]; /* scale: 0-15 */ 
             if(is_p != 7) {
               real t1,t2;
               sb  = bi->shortDiff[sfb];
               idx = bi->shortIdx[sfb] + lwin;
               t1  = tab1[is_p]; t2 = tab2[is_p];
               for (; sb > 0; sb--,idx+=3) {
                 real v = xr[0][idx];
                 xr[0][idx] = REAL_MUL(v, t1);
                 xr[1][idx] = REAL_MUL(v, t2);
               }
             }
           }

#if 1
/* in the original: copy 10 to 11 , here: copy 11 to 12 
maybe still wrong??? (copy 12 to 13?) */
           is_p = scalefac[11*3+lwin-gr_info->mixed_block_flag]; /* scale: 0-15 */
           sb   = bi->shortDiff[12];
           idx  = bi->shortIdx[12] + lwin;
#else
           is_p = scalefac[10*3+lwin-gr_info->mixed_block_flag]; /* scale: 0-15 */
           sb   = bi->shortDiff[11];
           idx  = bi->shortIdx[11] + lwin;
#endif
           if(is_p != 7) {
             real t1,t2;
             t1 = tab1[is_p]; t2 = tab2[is_p];
             for ( ; sb > 0; sb--,idx+=3 ) {  
               real v = xr[0][idx];
               xr[0][idx] = REAL_MUL(v, t1);
               xr[1][idx] = REAL_MUL(v, t2);
             }
           }
         } /* end for(lwin; .. ; . ) */

/* also check l-part, if ALL bands in the three windows are 'empty'
 * and mode = mixed_mode 
 */
         if (do_l) {
           int sfb = gr_info->maxbandl;
           int idx = bi->longIdx[sfb];

           for ( ; sfb<8; sfb++ ) {
             int sb = bi->longDiff[sfb];
             int is_p = scalefac[sfb]; /* scale: 0-15 */
             if(is_p != 7) {
               real t1,t2;
               t1 = tab1[is_p]; t2 = tab2[is_p];
               for ( ; sb > 0; sb--,idx++) {
                 real v = xr[0][idx];
                 xr[0][idx] = REAL_MUL(v, t1);
                 xr[1][idx] = REAL_MUL(v, t2);
               }
             }
             else 
               idx += sb;
           }
         }     
      } 
      else { /* ((gr_info->block_type != 2)) */
       int sfb = gr_info->maxbandl;
       int is_p,idx = bi->longIdx[sfb];

/* hmm ... maybe the maxbandl stuff for i-stereo is buggy? */
       if(sfb <= 21) { 
        for ( ; sfb<21; sfb++) {
          int sb = bi->longDiff[sfb];
          is_p = scalefac[sfb]; /* scale: 0-15 */
          if(is_p != 7) {
            real t1,t2;
            t1 = tab1[is_p]; t2 = tab2[is_p];
            for ( ; sb > 0; sb--,idx++) {
               real v = xr[0][idx];
               xr[0][idx] = REAL_MUL(v, t1);
               xr[1][idx] = REAL_MUL(v, t2);
            }
          }
          else
            idx += sb;
        }

        is_p = scalefac[20];
        if(is_p != 7) {  /* copy l-band 20 to l-band 21 */
          int sb;
          real t1 = tab1[is_p],t2 = tab2[is_p]; 

          for ( sb = bi->longDiff[21]; sb > 0; sb--,idx++ ) {
            real v = xr[0][idx];
            xr[0][idx] = REAL_MUL(v, t1);
            xr[1][idx] = REAL_MUL(v, t2);
          }
        }
       }        /* end: if(sfb <= 21) */
      } /* ... */
}

static void III_antialias(real xr[SBLIMIT][SSLIMIT],struct gr_info_s *gr_info) {
   int sblim;

   if(gr_info->block_type == 2) {
      if(!gr_info->mixed_block_flag) 
        return;
      sblim = 1; 
   }
   else {
     sblim = gr_info->maxb-1;
   }

   /* 31 alias-reduction operations between each pair of sub-bands */
   /* with 8 butterflies between each pair                         */

   {
     int sb;
     real *xr1=(real *) xr[1];

     for(sb=sblim;sb;sb--,xr1+=10) {
       int ss;
       real *cs=aa_cs,*ca=aa_ca;
       real *xr2 = xr1;

       for(ss=7;ss>=0;ss--) {    /* upper and lower butterfly inputs */
         register real bu = *--xr2,bd = *xr1;
         *xr2   = (bu * (*cs)   ) - (bd * (*ca)   );
         *xr1++ = (bd * (*cs++) ) + (bu * (*ca++) );
       }
     }
     
  }
}

#include "dct64.c"
#include "dct36.c"
#include "dct12.c"

#include "decod386.c"

/*
 * III_hybrid
 */
 
static dct36_func_t dct36_func;
  
static void III_hybrid(real fsIn[SBLIMIT][SSLIMIT],real tsOut[SSLIMIT][SBLIMIT],
   int ch,struct gr_info_s *gr_info)
{
   real *tspnt = (real *) tsOut;
   static real block[2][2][SBLIMIT*SSLIMIT] = { { { 0, } } };
   static int blc[2]={0,0};
   real *rawout1,*rawout2;
   int bt;
   int sb = 0;

   {
     int b = blc[ch];
     rawout1=block[b][ch];
     b=-b+1;
     rawout2=block[b][ch];
     blc[ch] = b;
   }

   if(gr_info->mixed_block_flag) {
     sb = 2;
     (*dct36_func)(fsIn[0],rawout1,rawout2,win[0],tspnt);
     (*dct36_func)(fsIn[1],rawout1+18,rawout2+18,win1[0],tspnt+1);
     rawout1 += 36; rawout2 += 36; tspnt += 2;
   }
 
   bt = gr_info->block_type;
   if(bt == 2) {
     for (; sb<gr_info->maxb; sb+=2,tspnt+=2,rawout1+=36,rawout2+=36) {
       dct12(fsIn[sb],rawout1,rawout2,win[2],tspnt);
       dct12(fsIn[sb+1],rawout1+18,rawout2+18,win1[2],tspnt+1);
     }
   }
   else {
     for (; sb<gr_info->maxb; sb+=2,tspnt+=2,rawout1+=36,rawout2+=36) {
       (*dct36_func)(fsIn[sb],rawout1,rawout2,win[bt],tspnt);
       (*dct36_func)(fsIn[sb+1],rawout1+18,rawout2+18,win1[bt],tspnt+1);
     }
   }

   for(;sb<SBLIMIT;sb++,tspnt++) {
     int i;
     for(i=0;i<SSLIMIT;i++) {
       tspnt[i*SBLIMIT] = *rawout1++;
       *rawout2++ = 0.0;
     }
   }
}

/*
 * main layer3 handler
 */
/* int do_layer3(struct frame *fr,int outmode,struct audio_info_struct *ai) */
static int do_layer3(struct frame *fr,int single){
  int gr, ch, ss,clip=0;
  int scalefacs[2][39]; /* max 39 for short[13][3] mode, mixed: 38, long: 22 */
  struct III_sideinfo sideinfo;
  int stereo = fr->stereo;
  int ms_stereo,i_stereo;
  int sfreq = fr->sampling_frequency;
  int stereo1,granules;

//  if (fr->error_protection) getbits(16); /* skip crc */

  if(stereo == 1) { /* stream is mono */
    stereo1 = 1;
    single = 0;
  } else
  if(single >= 0) /* stream is stereo, but force to mono */
    stereo1 = 1;
  else
    stereo1 = 2;

  if(fr->mode == MPG_MD_JOINT_STEREO) {
    ms_stereo = (fr->mode_ext & 0x2)>>1;
    i_stereo  = fr->mode_ext & 0x1;
  } else
    ms_stereo = i_stereo = 0;

  if(!III_get_side_info(&sideinfo,stereo,ms_stereo,sfreq,single,fr->lsf))
    return -1;
  
  set_pointer(sideinfo.main_data_begin);

  granules = (fr->lsf) ? 1 : 2;
  for (gr=0;gr<granules;gr++){
    DECLARE_ALIGNED(16, real, hybridIn[2][SBLIMIT][SSLIMIT]);
    DECLARE_ALIGNED(16, real, hybridOut[2][SSLIMIT][SBLIMIT]);

    { struct gr_info_s *gr_info = &(sideinfo.ch[0].gr[gr]);
      int part2bits;
      if(fr->lsf)
        part2bits = III_get_scale_factors_2(scalefacs[0],gr_info,0);
      else
        part2bits = III_get_scale_factors_1(scalefacs[0],gr_info);
      if(III_dequantize_sample(hybridIn[0], scalefacs[0],gr_info,sfreq,part2bits))
        return clip;
    }

    if(stereo == 2) {
      struct gr_info_s *gr_info = &(sideinfo.ch[1].gr[gr]);
      
      int part2bits;
      if(fr->lsf) 
        part2bits = III_get_scale_factors_2(scalefacs[1],gr_info,i_stereo);
      else
        part2bits = III_get_scale_factors_1(scalefacs[1],gr_info);

      if(III_dequantize_sample(hybridIn[1],scalefacs[1],gr_info,sfreq,part2bits))
          return clip;

      if(ms_stereo) {
        int i;
        int maxb = sideinfo.ch[0].gr[gr].maxb;
        if(sideinfo.ch[1].gr[gr].maxb > maxb)
            maxb = sideinfo.ch[1].gr[gr].maxb;
        for(i=0;i<SSLIMIT*maxb;i++) {
          real tmp0 = ((real *)hybridIn[0])[i];
          real tmp1 = ((real *)hybridIn[1])[i];
          ((real *)hybridIn[0])[i] = tmp0 + tmp1;
          ((real *)hybridIn[1])[i] = tmp0 - tmp1;
        }
      }

      if(i_stereo)
        III_i_stereo(hybridIn,scalefacs[1],gr_info,sfreq,ms_stereo,fr->lsf);

      if(ms_stereo || i_stereo || (single == 3) ) {
        if(gr_info->maxb > sideinfo.ch[0].gr[gr].maxb) 
          sideinfo.ch[0].gr[gr].maxb = gr_info->maxb;
        else
          gr_info->maxb = sideinfo.ch[0].gr[gr].maxb;
      }

      switch(single) {
        case 3: {
          register int i;
          register real *in0 = (real *) hybridIn[0],*in1 = (real *) hybridIn[1];
          for(i=0;i<SSLIMIT*gr_info->maxb;i++,in0++)
            *in0 = (*in0 + *in1++); /* *0.5 done by pow-scale */ 
          break; }
        case 1: {
          register int i;
          register real *in0 = (real *) hybridIn[0],*in1 = (real *) hybridIn[1];
          for(i=0;i<SSLIMIT*gr_info->maxb;i++)
            *in0++ = *in1++;
          break; }
      }

    }  // if(stereo == 2)

    for(ch=0;ch<stereo1;ch++) {
      struct gr_info_s *gr_info = &(sideinfo.ch[ch].gr[gr]);
		  III_antialias(hybridIn[ch],gr_info);
		  III_hybrid(hybridIn[ch], hybridOut[ch], ch,gr_info);
    }

    for(ss=0;ss<SSLIMIT;ss++) {
      if(single >= 0) {
		    clip += (fr->synth_mono)(hybridOut[0][ss],pcm_sample,&pcm_point);
  		} else {
	  	  int p1 = pcm_point;
		    clip += (fr->synth)(hybridOut[0][ss],0,pcm_sample,&p1);
		    clip += (fr->synth)(hybridOut[1][ss],1,pcm_sample,&pcm_point);
      }
    }
    
  }

  return clip;
}