func: static void lms_update(WmallDecodeCtx *s, int ich, int ilms, int16_t input, int16_t pred)
  
  {
  
      int16_t icoef;
  
      int recent = s->cdlms[ich][ilms].recent;
  
      int16_t range = 1 << (s->bits_per_sample - 1);
  
      int bps = s->bits_per_sample > 16 ? 4 : 2; // bytes per sample
  
  
  
      if (input > pred) {
  
          for (icoef = 0; icoef < s->cdlms[ich][ilms].order; icoef++)
  
              s->cdlms[ich][ilms].coefs[icoef] +=
  
                  s->cdlms[ich][ilms].lms_updates[icoef + recent];
  
      } else {
  
          for (icoef = 0; icoef < s->cdlms[ich][ilms].order; icoef++)
  
              s->cdlms[ich][ilms].coefs[icoef] -=
  
                  s->cdlms[ich][ilms].lms_updates[icoef];     // XXX: [icoef + recent] ?
  
      }
  
      s->cdlms[ich][ilms].recent--;
  
      s->cdlms[ich][ilms].lms_prevvalues[recent] = av_clip(input, -range, range - 1);
  
  
  
      if (input > pred)
  
          s->cdlms[ich][ilms].lms_updates[recent] = s->update_speed[ich];
  
      else if (input < pred)
  
          s->cdlms[ich][ilms].lms_updates[recent] = -s->update_speed[ich];
  
  
  
      /* XXX: spec says:
  
      cdlms[iCh][ilms].updates[iRecent + cdlms[iCh][ilms].order >> 4] >>= 2;
  
      lms_updates[iCh][ilms][iRecent + cdlms[iCh][ilms].order >> 3] >>= 1;
  
  
  
          Questions is - are cdlms[iCh][ilms].updates[] and lms_updates[][][] two
  
          seperate buffers? Here I've assumed that the two are same which makes
  
          more sense to me.
  
      */
  
      s->cdlms[ich][ilms].lms_updates[recent + s->cdlms[ich][ilms].order >> 4] >>= 2;
  
      s->cdlms[ich][ilms].lms_updates[recent + s->cdlms[ich][ilms].order >> 3] >>= 1;
  
      /* XXX: recent + (s->cdlms[ich][ilms].order >> 4) ? */
  
  
  
      if (s->cdlms[ich][ilms].recent == 0) {
  
          /* XXX: This memcpy()s will probably fail if a fixed 32-bit buffer is used.
  
                  follow kshishkov's suggestion of using a union. */
  
          memcpy(s->cdlms[ich][ilms].lms_prevvalues + s->cdlms[ich][ilms].order,
  
                 s->cdlms[ich][ilms].lms_prevvalues,
  
                 bps * s->cdlms[ich][ilms].order);
  
          memcpy(s->cdlms[ich][ilms].lms_updates + s->cdlms[ich][ilms].order,
  
                 s->cdlms[ich][ilms].lms_updates,
  
                 bps * s->cdlms[ich][ilms].order);
  
          s->cdlms[ich][ilms].recent = s->cdlms[ich][ilms].order;
  
      }
  
  }
  