layer3.c

音频编码

    int i,max = -1;
    int cb = 0;
    int *m = map[sfreq][2];
    real v = 0.0;
    int mc = 0;

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

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

        if(!mc) {
          mc = *m++;
          v = gr_infos->pow2gain[((*scf++) + (*pretab++)) << shift];
          cb = *m++;
        }
        {
          short *val = (short *)h->table;
          while((y=*val++)<0) {
            if (get1bit(mp))
              val -= y;
            part2remain--;
          }
          x = y >> 4;
          y &= 0xf;
        }
        if (x == 15) {
          max = cb;
          part2remain -= h->linbits+1;
          x += getbits(mp,(int)h->linbits);
          if(get1bit(mp))
            *xrpnt++ = -ispow[x] * v;
          else
            *xrpnt++ =  ispow[x] * v;
        }
        else if(x) {
          max = cb;
          if(get1bit(mp))
            *xrpnt++ = -ispow[x] * v;
          else
            *xrpnt++ =  ispow[x] * v;
          part2remain--;
        }
        else
          *xrpnt++ = 0.0;

        if (y == 15) {
          max = cb;
          part2remain -= h->linbits+1;
          y += getbits(mp,(int)h->linbits);
          if(get1bit(mp))
            *xrpnt++ = -ispow[y] * v;
          else
            *xrpnt++ =  ispow[y] * v;
        }
        else if(y) {
          max = cb;
          if(get1bit(mp))
            *xrpnt++ = -ispow[y] * v;
          else
            *xrpnt++ =  ispow[y] * v;
          part2remain--;
        }
        else
          *xrpnt++ = 0.0;
      }
    }

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

      while((a=*val++)<0) {
        part2remain--;
        if(part2remain < 0) {
          part2remain++;
          a = 0;
          break;
        }
        if (get1bit(mp))
          val -= a;
      }
      for(i=0;i<4;i++) {
        if(!(i & 1)) {
          if(!mc) {
            mc = *m++;
            cb = *m++;
            v = gr_infos->pow2gain[((*scf++) + (*pretab++)) << shift];
          }
          mc--;
        }
        if ( (a & (0x8>>i)) ) {
          max = cb;
          part2remain--;
          if(part2remain < 0) {
            part2remain++;
            break;
          }
          if(get1bit(mp))
            *xrpnt++ = -v;
          else
            *xrpnt++ = v;
        }
        else
          *xrpnt++ = 0.0;
      }
    }

	/* 
     * zero part
     */
    for(i=(&xr[SBLIMIT][0]-xrpnt)>>1;i;i--) {
      *xrpnt++ = 0.0;
      *xrpnt++ = 0.0;
    }

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

  while( part2remain > 16 ) {
    getbits(mp,16); /* Dismiss stuffing Bits */
    part2remain -= 16;
  }
  if(part2remain > 0)
    getbits(mp,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_infos,int sfreq,int ms_stereo,int lsf)
{
      real (*xr)[SBLIMIT*SSLIMIT] = (real (*)[SBLIMIT*SSLIMIT] ) xr_buf;
      struct bandInfoStruct *bi = (struct bandInfoStruct *)&bandInfo[sfreq];
      real *tabl1,*tabl2;

      if(lsf) {
        int p = gr_infos->scalefac_compress & 0x1;
	    if(ms_stereo) {
          tabl1 = pow1_2[p]; tabl2 = pow2_2[p];
        }
        else {
          tabl1 = pow1_1[p]; tabl2 = pow2_1[p];
        }
      }
      else {
        if(ms_stereo) {
          tabl1 = tan1_2; tabl2 = tan2_2;
        }
        else {
          tabl1 = tan1_1; tabl2 = tan2_1;
        }
      }

      if (gr_infos->block_type == 2)
      {
         int lwin,do_l = 0;
         if( gr_infos->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_infos->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_infos->mixed_block_flag]; /* scale: 0-15 */ 
             if(is_p != 7) {
               real t1,t2;
               sb = bi->shortDiff[sfb];
               idx = bi->shortIdx[sfb] + lwin;
               t1 = tabl1[is_p]; t2 = tabl2[is_p];
               for (; sb > 0; sb--,idx+=3)
               {
                 real v = xr[0][idx];
                 xr[0][idx] = v * t1;
                 xr[1][idx] = 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_infos->mixed_block_flag]; /* scale: 0-15 */
           sb = bi->shortDiff[12];
           idx = bi->shortIdx[12] + lwin;
#else
           is_p = scalefac[10*3+lwin-gr_infos->mixed_block_flag]; /* scale: 0-15 */
           sb = bi->shortDiff[11];
           idx = bi->shortIdx[11] + lwin;
#endif
           if(is_p != 7)
           {
             real t1,t2;
             t1 = tabl1[is_p]; t2 = tabl2[is_p];
             for ( ; sb > 0; sb--,idx+=3 )
             {  
               real v = xr[0][idx];
               xr[0][idx] = v * t1;
               xr[1][idx] = v * t2;
             }
           }
         } /* end for(lwin; .. ; . ) */

         if (do_l)
         {
/* also check l-part, if ALL bands in the three windows are 'empty'
 * and mode = mixed_mode 
 */
           int sfb = gr_infos->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 = tabl1[is_p]; t2 = tabl2[is_p];
               for ( ; sb > 0; sb--,idx++)
               {
                 real v = xr[0][idx];
                 xr[0][idx] = v * t1;
                 xr[1][idx] = v * t2;
               }
             }
             else 
               idx += sb;
           }
         }     
      } 
      else /* ((gr_infos->block_type != 2)) */
      {
        int sfb = gr_infos->maxbandl;
        int is_p,idx = bi->longIdx[sfb];
        for ( ; sfb<21; sfb++)
        {
          int sb = bi->longDiff[sfb];
          is_p = scalefac[sfb]; /* scale: 0-15 */
          if(is_p != 7) {
            real t1,t2;
            t1 = tabl1[is_p]; t2 = tabl2[is_p];
            for ( ; sb > 0; sb--,idx++)
            {
               real v = xr[0][idx];
               xr[0][idx] = v * t1;
               xr[1][idx] = v * t2;
            }
          }
          else
            idx += sb;
        }

        is_p = scalefac[20]; /* copy l-band 20 to l-band 21 */
        if(is_p != 7)
        {
          int sb;
          real t1 = tabl1[is_p],t2 = tabl2[is_p]; 

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

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

   if(gr_infos->block_type == 2)
   {
      if(!gr_infos->mixed_block_flag) 
        return;
      sblim = 1; 
   }
   else {
     sblim = gr_infos->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 */
         real bu = *--xr2,bd = *xr1;
         *xr2   = (bu * (*cs)   ) - (bd * (*ca)   );
         *xr1++ = (bd * (*cs++) ) + (bu * (*ca++) );
       }
     }
  }
}

/*
 DCT insipired by Jeff Tsay's DCT from the maplay package
 this is an optimized version with manual unroll.

 References:
 [1] S. Winograd: "On Computing the Discrete Fourier Transform",
     Mathematics of Computation, Volume 32, Number 141, January 1978,
     Pages 175-199
*/

static void dct36(real *inbuf,real *o1,real *o2,real *wintab,real *tsbuf)
{
  {
    real *in = inbuf;

    in[17]+=in[16]; in[16]+=in[15]; in[15]+=in[14];
    in[14]+=in[13]; in[13]+=in[12]; in[12]+=in[11];
    in[11]+=in[10]; in[10]+=in[9];  in[9] +=in[8];
    in[8] +=in[7];  in[7] +=in[6];  in[6] +=in[5];
    in[5] +=in[4];  in[4] +=in[3];  in[3] +=in[2];
    in[2] +=in[1];  in[1] +=in[0];

    in[17]+=in[15]; in[15]+=in[13]; in[13]+=in[11]; in[11]+=in[9];
    in[9] +=in[7];  in[7] +=in[5];  in[5] +=in[3];  in[3] +=in[1];


  {

#define MACRO0(v) { \
    real tmp; \
    out2[9+(v)] = (tmp = sum0 + sum1) * w[27+(v)]; \
    out2[8-(v)] = tmp * w[26-(v)];  } \
    sum0 -= sum1; \
    ts[SBLIMIT*(8-(v))] = out1[8-(v)] + sum0 * w[8-(v)]; \
    ts[SBLIMIT*(9+(v))] = out1[9+(v)] + sum0 * w[9+(v)]; 
#define MACRO1(v) { \
	real sum0,sum1; \
    sum0 = tmp1a + tmp2a; \
	sum1 = (tmp1b + tmp2b) * tfcos36[(v)]; \
	MACRO0(v); }
#define MACRO2(v) { \
    real sum0,sum1; \
    sum0 = tmp2a - tmp1a; \
    sum1 = (tmp2b - tmp1b) * tfcos36[(v)]; \
	MACRO0(v); }

    const real *c = COS9;
    real *out2 = o2;
	real *w = wintab;
	real *out1 = o1;
	real *ts = tsbuf;

    real ta33,ta66,tb33,tb66;

    ta33 = in[2*3+0] * c[3];
    ta66 = in[2*6+0] * c[6];
    tb33 = in[2*3+1] * c[3];
    tb66 = in[2*6+1] * c[6];

    { 
      real tmp1a,tmp2a,tmp1b,tmp2b;
      tmp1a =             in[2*1+0] * c[1] + ta33 + in[2*5+0] * c[5] + in[2*7+0] * c[7];
      tmp1b =             in[2*1+1] * c[1] + tb33 + in[2*5+1] * c[5] + in[2*7+1] * c[7];
      tmp2a = in[2*0+0] + in[2*2+0] * c[2] + in[2*4+0] * c[4] + ta66 + in[2*8+0] * c[8];
      tmp2b = in[2*0+1] + in[2*2+1] * c[2] + in[2*4+1] * c[4] + tb66 + in[2*8+1] * c[8];

      MACRO1(0);
      MACRO2(8);
    }

    {
      real tmp1a,tmp2a,tmp1b,tmp2b;
      tmp1a = ( in[2*1+0] - in[2*5+0] - in[2*7+0] ) * c[3];
      tmp1b = ( in[2*1+1] - in[2*5+1] - in[2*7+1] ) * c[3];
      tmp2a = ( in[2*2+0] - in[2*4+0] - in[2*8+0] ) * c[6] - in[2*6+0] + in[2*0+0];
      tmp2b = ( in[2*2+1] - in[2*4+1] - in[2*8+1] ) * c[6] - in[2*6+1] + in[2*0+1];

      MACRO1(1);
      MACRO2(7);
    }

    {
      real tmp1a,tmp2a,tmp1b,tmp2b;
      tmp1a =             in[2*1+0] * c[5] - ta33 - in[2*5+0] * c[7] + in[2*7+0] * c[1];
      tmp1b =             in[2*1+1] * c[5] - tb33 - in[2*5+1] * c[7] + in[2*7+1] * c[1];
      tmp2a = in[2*0+0] - in[2*2+0] * c[8] - in[2*4+0] * c[2] + ta66 + in[2*8+0] * c[4];
      tmp2b = in[2*0+1] - in[2*2+1] * c[8] - in[2*4+1] * c[2] + tb66 + in[2*8+1] * c[4];

      MACRO1(2);
      MACRO2(6);
    }

    {
      real tmp1a,tmp2a,tmp1b,tmp2b;
      tmp1a =             in[2*1+0] * c[7] - ta33 + in[2*5+0] * c[1] - in[2*7+0] * c[5];
      tmp1b =             in[2*1+1] * c[7] - tb33 + in[2*5+1] * c[1] - in[2*7+1] * c[5];
      tmp2a = in[2*0+0] - in[2*2+0] * c[4] + in[2*4+0] * c[8] + ta66 - in[2*8+0] * c[2];
      tmp2b = in[2*0+1] - in[2*2+1] * c[4] + in[2*4+1] * c[8] + tb66 - in[2*8+1] * c[2];

      MACRO1(3);
      MACRO2(5);
    }

	{
		real sum0,sum1;
    	sum0 =  in[2*0+0] - in[2*2+0] + in[2*4+0] - in[2*6+0] + in[2*8+0];
    	sum1 = (in[2*0+1] - in[2*2+1] + in[2*4+1] - in[2*6+1] + in[2*8+1] ) * tfcos36[4];
		MACRO0(4);
	}
  }

  }
}

/*
 * new DCT12
 */
static void dct12(real *in,real *rawout1,real *rawout2,real *wi,real *ts)
{
#define DCT12_PART1 \
             in5 = in[5*3];  \
     in5 += (in4 = in[4*3]); \
     in4 += (in3 = in[3*3]); \
     in3 += (in2 = in[2*3]); \