layer3.c

从 IEEE 1394总线接收传输流

    }

    /*
     * 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++;
            if(cb == 21)
              v = 0.0;
            else
              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);
  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;

#if 1
      int tab;
/* TODO: optimize as static */
      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];
#else
      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

      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] = 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_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] = v * t1;
               xr[1][idx] = 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] = v * t1;
                 xr[1][idx] = v * t2;
               }
             }
             else 
               idx += sb;
           }
         }     
      } 
      else { /* ((gr_info->block_type != 2)) */
        int sfb = gr_info->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 = tab1[is_p]; t2 = tab2[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];
        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] = v * t1;
            xr[1][idx] = v * t2;
          }
        }
      } /* ... */
}

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++) );
       }
     }
  }
}

/* 
// This is an optimized DCT from Jeff Tsay's maplay 1.2+ package.
// Saved one multiplication by doing the 'twiddle factor' stuff
// together with the window mul. (MH)
//
// This uses Byeong Gi Lee's Fast Cosine Transform algorithm, but the
// 9 point IDCT needs to be reduced further. Unfortunately, I don't
// know how to do that, because 9 is not an even number. - Jeff.
//
//////////////////////////////////////////////////////////////////
//
// 9 Point Inverse Discrete Cosine Transform
//
// This piece of code is Copyright 1997 Mikko Tommila and is freely usable
// by anybody. The algorithm itself is of course in the public domain.
//
// Again derived heuristically from the 9-point WFTA.
//
// The algorithm is optimized (?) for speed, not for small rounding errors or
// good readability.
//
// 36 additions, 11 multiplications
//
// Again this is very likely sub-optimal.
//
// The code is optimized to use a minimum number of temporary variables,
// so it should compile quite well even on 8-register Intel x86 processors.
// This makes the code quite obfuscated and very difficult to understand.
//
// References:
// [1] S. Winograd: "On Computing the Discrete Fourier Transform",
//     Mathematics of Computation, Volume 32, Number 141, January 1978,
//     Pages 175-199
*/

/*------------------------------------------------------------------*/
/*                                                                  */
/*    Function: Calculation of the inverse MDCT                     */
/*                                                                  */
/*------------------------------------------------------------------*/

static void dct36(real *inbuf,real *o1,real *o2,real *wintab,real *tsbuf)
{
#ifdef NEW_DCT9
  real tmp[18];
#endif

  {
    register 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];


#ifdef NEW_DCT9
#if 1
    {
     real t3;
     { 
      real t0, t1, t2;

      t0 = COS6_2 * (in[8] + in[16] - in[4]);
      t1 = COS6_2 * in[12];

      t3 = in[0];
      t2 = t3 - t1 - t1;
      tmp[1] = tmp[7] = t2 - t0;
      tmp[4]          = t2 + t0 + t0;
      t3 += t1;

      t2 = COS6_1 * (in[10] + in[14] - in[2]);
      tmp[1] -= t2;
      tmp[7] += t2;
     }
     {
      real t0, t1, t2;

      t0 = cos9[0] * (in[4] + in[8] );
      t1 = cos9[1] * (in[8] - in[16]);
      t2 = cos9[2] * (in[4] + in[16]);

      tmp[2] = tmp[6] = t3 - t0      - t2;
      tmp[0] = tmp[8] = t3 + t0 + t1;
      tmp[3] = tmp[5] = t3      - t1 + t2;
     }
    }
    {
      real t1, t2, t3;

      t1 = cos18[0] * (in[2]  + in[10]);
      t2 = cos18[1] * (in[10] - in[14]);
      t3 = COS6_1   * in[6];

      {
        real t0 = t1 + t2 + t3;
        tmp[0] += t0;
        tmp[8] -= t0;
      }

      t2 -= t3;
      t1 -= t3;

      t3 = cos18[2] * (in[2] + in[14]);

      t1 += t3;
      tmp[3] += t1;
      tmp[5] -= t1;

      t2 -= t3;
      tmp[2] += t2;
      tmp[6] -= t2;
    }

#else
    {
      real t0, t1, t2, t3, t4, t5, t6, t7;

      t1 = COS6_2 * in[12];
      t2 = COS6_2 * (in[8] + in[16] - in[4]);

      t3 = in[0] + t1;
      t4 = in[0] - t1 - t1;
      t5     = t4 - t2;
      tmp[4] = t4 + t2 + t2;

      t0 = cos9[0] * (in[4] + in[8]);
      t1 = cos9[1] * (in[8] - in[16]);

      t2 = cos9[2] * (in[4] + in[16]);

      t6 = t3 - t0 - t2;
      t0 += t3 + t1;
      t3 += t2 - t1;

      t2 = cos18[0] * (in[2]  + in[10]);
      t4 = cos18[1] * (in[10] - in[14]);
      t7 = COS6_1 * in[6];

      t1 = t2 + t4 + t7;
      tmp[0] = t0 + t1;
      tmp[8] = t0 - t1;
      t1 = cos18[2] * (in[2] + in[14]);
      t2 += t1 - t7;

      tmp[3] = t3 + t2;
      t0 = COS6_1 * (in[10] + in[14] - in[2]);
      tmp[5] = t3 - t2;

      t4 -= t1 + t7;

      tmp[1] = t5 - t0;
      tmp[7] = t5 + t0;
      tmp[2] = t6 + t4;
      tmp[6] = t6 - t4;
    }
#endif

    {
      real t0, t1, t2, t3, t4, t5, t6, t7;

      t1 = COS6_2 * in[13];
      t2 = COS6_2 * (in[9] + in[17] - in[5]);

      t3 = in[1] + t1;
      t4 = in[1] - t1 - t1;
      t5 = t4 - t2;

      t0 = cos9[0] * (in[5] + in[9]);
      t1 = cos9[1] * (in[9] - in[17]);

      tmp[13] = (t4 + t2 + t2) * tfcos36[17-13];
      t2 = cos9[2] * (in[5] + in[17]);

      t6 = t3 - t0 - t2;
      t0 += t3 + t1;
      t3 += t2 - t1;

      t2 = cos18[0] * (in[3]  + in[11]);
      t4 = cos18[1] * (in[11] - in[15]);
      t7 = COS6_1 * in[7];

      t1 = t2 + t4 + t7;
      tmp[17] = (t0 + t1) * tfcos36[17-17];
      tmp[9]  = (t0 - t1) * tfcos36[17-9];
      t1 = cos18[2] * (in[3] + in[15]);
      t2 += t1 - t7;

      tmp[14] = (t3 + t2) * tfcos36[17-14];
      t0 = COS6_1 * (in[11] + in[15] - in[3]);
      tmp[12] = (t3 - t2) * tfcos36[17-12];

      t4 -= t1 + t7;

      tmp[16] = (t5 - t0) * tfcos36[17-16];
      tmp[10] = (t5 + t0) * tfcos36[17-10];
      tmp[15] = (t6 + t4) * tfcos36[17-15];
      tmp[11] = (t6 - t4) * tfcos36[17-11];
   }

#define MACRO(v) { \
    real tmpval; \
    tmpval = tmp[(v)] + tmp[17-(v)]; \
    out2[9+(v)] = tmpval * w[27+(v)]; \