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