codecs/ilbc/StateConstructW.c

   1
   2 /******************************************************************
   3
   4
   5
   6     iLBC Speech Coder ANSI-C Source Code
   7
   8     StateConstructW.c
   9
  10     Copyright (C) The Internet Society (2004).
  11     All Rights Reserved.
  12
  13 ******************************************************************/
  14
  15 #include <math.h>
  16 #include <string.h>
  17
  18 #include "iLBC_define.h"
  19 #include "StateConstructW.h"
  20 #include "constants.h"
  21 #include "filter.h"
  22
  23 /*----------------------------------------------------------------*
  24  *  decoding of the start state
  25  *---------------------------------------------------------------*/
  26
  27 void StateConstructW(
  28     int idxForMax,      /* (i) 6-bit index for the quantization of
  29                                max amplitude */
  30     int *idxVec,    /* (i) vector of quantization indexes */
  31     float *syntDenum,   /* (i) synthesis filter denumerator */
  32     float *out,         /* (o) the decoded state vector */
  33     int len             /* (i) length of a state vector */
  34 ){
  35     float maxVal, tmpbuf[LPC_FILTERORDER+2*STATE_LEN], *tmp,
  36         numerator[LPC_FILTERORDER+1];
  37     float foutbuf[LPC_FILTERORDER+2*STATE_LEN], *fout;
  38     int k,tmpi;
  39
  40     /* decoding of the maximum value */
  41
  42     maxVal = state_frgqTbl[idxForMax];
  43     maxVal = (float)pow(10,maxVal)/(float)4.5;
  44
  45     /* initialization of buffers and coefficients */
  46
  47     memset(tmpbuf, 0, LPC_FILTERORDER*sizeof(float));
  48     memset(foutbuf, 0, LPC_FILTERORDER*sizeof(float));
  49     for (k=0; k<LPC_FILTERORDER; k++) {
  50         numerator[k]=syntDenum[LPC_FILTERORDER-k];
  51     }
  52     numerator[LPC_FILTERORDER]=syntDenum[0];
  53     tmp = &tmpbuf[LPC_FILTERORDER];
  54     fout = &foutbuf[LPC_FILTERORDER];
  55
  56     /* decoding of the sample values */
  57
  58     for (k=0; k<len; k++) {
  59         tmpi = len-1-k;
  60         /* maxVal = 1/scal */
  61
  62
  63         tmp[k] = maxVal*state_sq3Tbl[idxVec[tmpi]];
  64     }
  65
  66     /* circular convolution with all-pass filter */
  67
  68     memset(tmp+len, 0, len*sizeof(float));
  69     ZeroPoleFilter(tmp, numerator, syntDenum, 2*len,
  70         LPC_FILTERORDER, fout);
  71     for (k=0;k<len;k++) {
  72         out[k] = fout[len-1-k]+fout[2*len-1-k];
  73     }
  74 }
  75
  76