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/******************************************************************
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];
}
}
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