stateconstructw.c

PA1688网络电话机全部源程序

    
   /****************************************************************** 
    
       iLBC Speech Coder ANSI-C Source Code 
    
       StateConstructW.c  
    
       Copyright (c) 2001, 
       Global IP Sound AB. 
       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]; 
       } 
   }