iCBConstruct.c

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 /******************************************************************

 iLBC Speech Coder ANSI-C Source Code

 iCBConstruct.c

 Copyright (C) The Internet Society (2004).
 All Rights Reserved.

 ******************************************************************/

 #include <math.h>

 #include "iLBC_define.h"
 #include "gainquant.h"
 #include "getCBvec.h"

 /*----------------------------------------------------------------*
 * Convert the codebook indexes to make the search easier
 *---------------------------------------------------------------*/






 void index_conv_enc(
 int *index /* (i/o) Codebook indexes */
 ){
 int k;

 for (k=1; k<CB_NSTAGES; k++) {

 if ((index[k]>=108)&&(index[k]<172)) {
 index[k]-=64;
 } else if (index[k]>=236) {
 index[k]-=128;
 } else {
 /* ERROR */
 }
 }
 }

 void index_conv_dec(
 int *index /* (i/o) Codebook indexes */
 ){
 int k;

 for (k=1; k<CB_NSTAGES; k++) {

 if ((index[k]>=44)&&(index[k]<108)) {
 index[k]+=64;
 } else if ((index[k]>=108)&&(index[k]<128)) {
 index[k]+=128;
 } else {
 /* ERROR */
 }
 }
 }

 /*----------------------------------------------------------------*
 * Construct decoded vector from codebook and gains.
 *---------------------------------------------------------------*/

 void iCBConstruct(
 float *decvector, /* (o) Decoded vector */
 int *index, /* (i) Codebook indices */
 int *gain_index,/* (i) Gain quantization indices */
 float *mem, /* (i) Buffer for codevector construction */
 int lMem, /* (i) Length of buffer */
 int veclen, /* (i) Length of vector */
 int nStages /* (i) Number of codebook stages */
 ){
 int j,k;





 float gain[CB_NSTAGES];
 float cbvec[SUBL];

 /* gain de-quantization */

 gain[0] = gaindequant(gain_index[0], 1.0, 32);
 if (nStages > 1) {
 gain[1] = gaindequant(gain_index[1],
 (float)fabs(gain[0]), 16);
 }
 if (nStages > 2) {
 gain[2] = gaindequant(gain_index[2],
 (float)fabs(gain[1]), 8);
 }

 /* codebook vector construction and construction of
 total vector */

 getCBvec(cbvec, mem, index[0], lMem, veclen);
 for (j=0;j<veclen;j++){
 decvector[j] = gain[0]*cbvec[j];
 }
 if (nStages > 1) {
 for (k=1; k<nStages; k++) {
 getCBvec(cbvec, mem, index[k], lMem, veclen);
 for (j=0;j<veclen;j++) {
 decvector[j] += gain[k]*cbvec[j];
 }
 }
 }
 }