exc[i]=st->last_pitch_gain*exc[i-st->last_pitch] + .8*st->innov[i+offset];
static void nb_decode_lost(DecState *st, float *out, void *stack){   int i, sub;   float *awk1, *awk2, *awk3;   /*float exc_ener=0,g;*/   /* Shift all buffers by one frame */   speex_move(st->inBuf, st->inBuf+st->frameSize, (st->bufSize-st->frameSize)*sizeof(float));   speex_move(st->excBuf, st->excBuf+st->frameSize, (st->bufSize-st->frameSize)*sizeof(float));   awk1=PUSH(stack, (st->lpcSize+1), float);   awk2=PUSH(stack, (st->lpcSize+1), float);   awk3=PUSH(stack, (st->lpcSize+1), float);   for (sub=0;sub<st->nbSubframes;sub++)   {      int offset;      float *sp, *exc;      /* Offset relative to start of frame */      offset = st->subframeSize*sub;      /* Original signal */      sp=st->frame+offset;      /* Excitation */      exc=st->exc+offset;      /* Excitation after post-filter*/      /* Calculate perceptually enhanced LPC filter */      if (st->lpc_enh_enabled)      {         float r=.9;                  float k1,k2,k3;         k1=SUBMODE(lpc_enh_k1);         k2=SUBMODE(lpc_enh_k2);         k3=(1-(1-r*k1)/(1-r*k2))/r;         if (!st->lpc_enh_enabled)         {            k1=k2;            k3=0;         }         bw_lpc(k1, st->interp_qlpc, awk1, st->lpcSize);         bw_lpc(k2, st->interp_qlpc, awk2, st->lpcSize);         bw_lpc(k3, st->interp_qlpc, awk3, st->lpcSize);               }              /* Make up a plausible excitation */      /* THIS CAN BE IMPROVED */      for (i=0;i<st->subframeSize;i++)      {         exc[i]=st->last_pitch_gain*exc[i-st->last_pitch] +          .8*st->innov[i+offset];      }      for (i=0;i<st->subframeSize;i++)         sp[i]=exc[i];            /* Signal synthesis */      if (st->lpc_enh_enabled)      {         filter_mem2(sp, awk2, awk1, sp, st->subframeSize, st->lpcSize,                      st->mem_sp+st->lpcSize);         filter_mem2(sp, awk3, st->interp_qlpc, sp, st->subframeSize, st->lpcSize,                      st->mem_sp);      } else {         for (i=0;i<st->lpcSize;i++)            st->mem_sp[st->lpcSize+i] = 0;         iir_mem2(sp, st->interp_qlpc, sp, st->subframeSize, st->lpcSize,                      st->mem_sp);      }     }   out[0] = st->frame[0] + st->preemph*st->pre_mem;   for (i=1;i<st->frameSize;i++)      out[i]=st->frame[i] + st->preemph*out[i-1];   st->pre_mem=out[st->frameSize-1];      st->first = 0;   st->count_lost++;}