/******************************************************************       iLBC Speech Coder ANSI-C Source Code       StateConstructW.c       Copyright (C) The Internet Society (2004).       All Rights Reserved.   ******************************************************************/   #include <math.h>   #include <string.h>   #include "iLBC_define.h"   #include "constants.h"   #include "filter.h"   /*----------------------------------------------------------------*    *  decoding of the start state    *---------------------------------------------------------------*/   void StateConstructW(       int idxForMax,      /* (i) 6-bit index for the quantization of                                  max amplitude */       int *idxVec,    /* (i) vector of quantization indexes */       float *syntDenum,   /* (i) synthesis filter denumerator */       float *out,         /* (o) the decoded state vector */       int len             /* (i) length of a state vector */   ){       float maxVal, tmpbuf[LPC_FILTERORDER+2*STATE_LEN], *tmp,           numerator[LPC_FILTERORDER+1];       float foutbuf[LPC_FILTERORDER+2*STATE_LEN], *fout;       int k,tmpi;       /* decoding of the maximum value */       maxVal = state_frgqTbl[idxForMax];       maxVal = (float)pow(10,maxVal)/(float)4.5;       /* initialization of buffers and coefficients */       memset(tmpbuf, 0, LPC_FILTERORDER*sizeof(float));       memset(foutbuf, 0, LPC_FILTERORDER*sizeof(float));       for (k=0; k<LPC_FILTERORDER; k++) {           numerator[k]=syntDenum[LPC_FILTERORDER-k];       }       numerator[LPC_FILTERORDER]=syntDenum[0];       tmp = &tmpbuf[LPC_FILTERORDER];       fout = &foutbuf[LPC_FILTERORDER];       /* decoding of the sample values */       for (k=0; k<len; k++) {           tmpi = len-1-k;           /* maxVal = 1/scal */           tmp[k] = maxVal*state_sq3Tbl[idxVec[tmpi]];       }       /* circular convolution with all-pass filter */       memset(tmp+len, 0, len*sizeof(float));       ZeroPoleFilter(tmp, numerator, syntDenum, 2*len,           LPC_FILTERORDER, fout);       for (k=0;k<len;k++) {           out[k] = fout[len-1-k]+fout[2*len-1-k];       }   }