esram.c

MP3的代码很实用 MP3的代码很实用

	count = max;
    if(gr_info->mixed_block_flag) {
      /*max[3] = -1;
      max[0] = max[1] = max[2] = 2;*/   
      *count = 2; count++;
      *count = 2; count++;
      *count = 2; count++;
      *count = -1;
      m = map[sfreq][0];
      me = mapend[sfreq][0];
    }
    else {
      /*max[0] = max[1] = max[2] = max[3] = -1;*/
      *count = -1; count++;
      *count = -1; count++;
      *count = -1; count++;
      *count = -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;
          while((y=*val++)<0) {
	     GET1BIT();
            if (rval)
              val -= y;
            part2remain--;
          }
          x = y >> 4;
          y &= 0xf;
        }
        if(x == 15) {
          max[lwin] = cb;
          part2remain -= h->linbits+1;
          x += getbits(h->linbits);
          deq_pow(x, v);			// ispow[x] * v;
          GET1BIT();
          if(rval)
            *xrpnt = -deq;
          else
            *xrpnt = deq;
        }
        else if(x) {
          max[lwin] = cb;
          deq_pow(x, v);			// ispow[x] * v;
          GET1BIT();
          if(rval)
            *xrpnt = -deq;
          else
            *xrpnt = deq;
          part2remain--;
        }
        else
          *xrpnt = 0;
        xrpnt += step;
        if(y == 15) {
          max[lwin] = cb;
          part2remain -= h->linbits+1;
          y += getbits(h->linbits);
          deq_pow(y, v);			// ispow[y] * v;
          GET1BIT();
          if(rval)
            *xrpnt = -deq;
          else
            *xrpnt = deq;
        }
        else if(y) {
          max[lwin] = cb;
          deq_pow(y, v);			// ispow[y] * v;
          GET1BIT();
          if(rval)
            *xrpnt = -deq;
          else
            *xrpnt = deq;
          part2remain--;
        }
        else
          *xrpnt = 0;
        xrpnt += step;
      }
    }
    for(;l3 && (part2remain > 0);l3--) {
      struct newhuff *h = htc+gr_info->count1table_select;
      register short *val = h->table;
      register short a;

      while((a=*val++)<0) {
        part2remain--;
        if(part2remain < 0) {
          part2remain++;
          a = 0;
          break;
        }
	GET1BIT();
        if (rval)
          val -= a;
      }

      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;
          part2remain--;
          if(part2remain < 0) {
            part2remain++;
            break;
          }
	   GET1BIT();
          if(rval) 
            *xrpnt = -gainpow2[(-v) & 3]>>(v >> 2);			// -v;
          else
            *xrpnt =  gainpow2[(-v) & 3]>>(v >> 2);			// v
        }
        else
          *xrpnt = 0;
        xrpnt += step;
      }
    }
 
    while( m < me ) {
      if(!mc) {
        mc = *m++;
        xrpnt = ((real *) xr) + *m++;
        if( (*m++) == 3)
          step = 1;
        else
          step = 3;
        m++; /* cb */
      }
      mc--;
      *xrpnt = 0;
      xrpnt += step;
      *xrpnt = 0;
      xrpnt += step;
/* we could add a little opt. here:
 * if we finished a band for window 3 or a long band
 * further bands could copied in a simple loop without a
 * special 'map' decoding
 */
    }

    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;
    register int *m = map[sfreq][2];
    register real v = 0;
    register 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++;
          v = gr_info->pow2gain + (((*scf++) + (*pretab++)) << shift);
          cb = *m++;
        }
        {
          register short *val = h->table;
          while((y=*val++)<0) {
	     GET1BIT();
            if (rval)
              val -= y;
            part2remain--;
          }
          x = y >> 4;
          y &= 0xf;
        }
        if (x == 15) {
          max = cb;
          part2remain -= h->linbits+1;
          x += getbits(h->linbits);
          deq_pow(x, v);			// ispow[x] * v;
          GET1BIT();
          if(rval)
            *xrpnt++ = -deq;
          else
            *xrpnt++ = deq;
        }
        else if(x) {
          max = cb;
          deq_pow(x, v);			// ispow[x] * v;
          GET1BIT();
          if(rval)
            *xrpnt++ = -deq;
          else
            *xrpnt++ = deq;
          part2remain--;
        }
        else
          *xrpnt++ = 0;

        if (y == 15) {
          max = cb;
          part2remain -= h->linbits+1;
          y += getbits(h->linbits);
          deq_pow(y, v);			// ispow[y] * v;
	   GET1BIT();
          if(rval)
            *xrpnt++ = -deq;
          else
            *xrpnt++ = deq;
        }
        else if(y) {
          max = cb;
          deq_pow(y, v);			// ispow[y] * v;
          GET1BIT();
          if(rval)
            *xrpnt++ = -deq;
          else
            *xrpnt++ = deq;
          part2remain--;
        }
        else
          *xrpnt++ = 0;
      }
    }

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

      while((a=*val++)<0) {
        part2remain--;
        if(part2remain < 0) {
          part2remain++;
          a = 0;
          break;
        }
	GET1BIT();
        if (rval)
          val -= a;
      }

      for(i=0;i<4;i++) {
        if(!(i & 1)) {
          if(!mc) {
            mc = *m++;
            cb = *m++;
            v = gr_info->pow2gain + (((*scf++) + (*pretab++)) << shift);
          }
          mc--;
        }
        if ( (a & (0x8>>i)) ) {
          max = cb;
          part2remain--;
          if(part2remain < 0) {
            part2remain++;
            break;
          }
	   GET1BIT();	  
          if(rval)
            *xrpnt++ = -gainpow2[(-v) & 3]>>(v >> 2);			// -v;
          else
            *xrpnt++ =  gainpow2[(-v) & 3]>>(v >> 2);			// v;
        }
        else
          *xrpnt++ = 0;
      }
    }

	/* 
     * zero part
     */
    for(i=(&xr[SBLIMIT][0]-xrpnt)>>1;i;i--) {
      *xrpnt++ = 0;
      *xrpnt++ = 0;
    }

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

  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;
}


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   = MUL24(bu, *cs  ) - MUL24(bd, *ca  );
         *xr1++ = MUL24(bd, *cs++) + MUL24(bu, *ca++);
       }
     }
  }
}


/*
 * read scalefactors
 */
 #if 0
int III_get_scale_factors_1(int *scf,struct gr_info_s *gr_info)
{
   static 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);
           *scf++ = getbits_fast(num0);
           *scf++ = getbits_fast(num0);
           *scf++ = getbits_fast(num0);
           *scf++ = getbits_fast(num0);
           *scf++ = getbits_fast(num0);
           *scf++ = getbits_fast(num0);
           *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++ = getbits_fast(num1);
        *scf++ = getbits_fast(num1);
        *scf++ = getbits_fast(num1);
        *scf++ = getbits_fast(num1);
        *scf++ = getbits_fast(num1);
        *scf++ = getbits_fast(num1);
        *scf++ = getbits_fast(num1);
		*scf++ = getbits_fast(num1);
		*scf++ = getbits_fast(num1);
		*scf++ = getbits_fast(num1);
		*scf++ = getbits_fast(num1);
		*scf++ = getbits_fast(num1);
		*scf++ = getbits_fast(num1);
		*scf++ = getbits_fast(num1);
		*scf++ = getbits_fast(num1);
		*scf++ = getbits_fast(num1);
		*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);
           *scf++ = getbits_fast(num0);
           *scf++ = getbits_fast(num0);
           *scf++ = getbits_fast(num0);
           *scf++ = getbits_fast(num0);
           *scf++ = getbits_fast(num0);
		   *scf++ = getbits_fast(num0);
		   *scf++ = getbits_fast(num0);
		   *scf++ = getbits_fast(num0);
		   *scf++ = getbits_fast(num0);
		   *scf++ = getbits_fast(num0);
//         for(i=10;i;i--)
           *scf++ = getbits_fast(num1);
           *scf++ = getbits_fast(num1);
           *scf++ = getbits_fast(num1);
           *scf++ = getbits_fast(num1);
           *scf++ = getbits_fast(num1);
           *scf++ = getbits_fast(num1);
           *scf++ = getbits_fast(num1);
           *scf++ = getbits_fast(num1);
           *scf++ = getbits_fast(num1);
           *scf++ = getbits_fast(num1);
         numbits = (num0 + num1) * 10 + num0;
      }
      else {
        numbits = 0;
        if(!(scfsi & 0x8)) {
//          for (i=6;i;i--)