/*  * Mpeg Layer-2 audio decoder  * -------------------------- * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README' * *//* $Id: layer2.c,v 1.20 2004/04/14 22:15:44 robert Exp $ */#ifdef HAVE_CONFIG_H# include <config.h>#endif#ifdef USE_LAYER_2#include "common.h"#include "layer2.h"#include "l2tables.h"#include "decode_i386.h"#ifdef WITH_DMALLOC#include <dmalloc.h>#endifstatic 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 voidII_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 *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 voidII_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 *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=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 */      if ( (ba=*bita++) )      {        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){  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 } } };  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*)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;}#endif