www.pudn.com > g729.rar > cor_func.c

/* 
   ITU-T G.729A Speech Coder    ANSI-C Source Code 
   Version 1.1    Last modified: September 1996 
 
   Copyright (c) 1996, 
   AT&T, France Telecom, NTT, Universite de Sherbrooke 
   All rights reserved. 
*/ 
 
/* Functions Corr_xy2() and Cor_h_x()   */ 
 
#include "typedef.h" 
#include "basic_op.h" 
#include "ld8a.h" 
 
/*---------------------------------------------------------------------------* 
 * Function corr_xy2()                                                       * 
 * ~~~~~~~~~~~~~~~~~~~                                                       * 
 * Find the correlations between the target xn[], the filtered adaptive      * 
 * codebook excitation y1[], and the filtered 1st codebook innovation y2[].  * 
 *   g_coeff[2]:exp_g_coeff[2] =                                      * 
 *   g_coeff[3]:exp_g_coeff[3] = -2                                   * 
 *   g_coeff[4]:exp_g_coeff[4] = 2                                    * 
 *---------------------------------------------------------------------------*/ 
 
void Corr_xy2( 
      Word16 xn[],           /* (i) Q0  :Target vector.                  */ 
      Word16 y1[],           /* (i) Q0  :Adaptive codebook.              */ 
      Word16 y2[],           /* (i) Q12 :Filtered innovative vector.     */ 
      Word16 g_coeff[],      /* (o) Q[exp]:Correlations between xn,y1,y2 */ 
      Word16 exp_g_coeff[]   /* (o)       :Q-format of g_coeff[]         */ 
) 
{ 
      Word16   i,exp; 
      Word16   exp_y2y2,exp_xny2,exp_y1y2; 
      Word16   y2y2,    xny2,    y1y2; 
      Word32   L_acc; 
      Word16   scaled_y2[L_SUBFR];       /* Q9 */ 
 
      /*------------------------------------------------------------------* 
       * Scale down y2[] from Q12 to Q9 to avoid overflow                 * 
       *------------------------------------------------------------------*/ 
      for(i=0; i */ 
      L_acc = 1;                       /* Avoid case of all zeros */ 
      for(i=0; i */ 
      L_acc = 1;                       /* Avoid case of all zeros */ 
      for(i=0; i */ 
 
      /* Compute scalar product  */ 
      L_acc = 1;                       /* Avoid case of all zeros */ 
      for(i=0; i */ 
 
      return; 
} 
 
 
/*--------------------------------------------------------------------------* 
 *  Function  Cor_h_X()                                                     * 
 *  ~~~~~~~~~~~~~~~~~~~                                                     * 
 * Compute correlations of input response h[] with the target vector X[].   * 
 *--------------------------------------------------------------------------*/ 
 
void Cor_h_X( 
     Word16 h[],        /* (i) Q12 :Impulse response of filters      */ 
     Word16 X[],        /* (i)     :Target vector                    */ 
     Word16 D[]         /* (o)     :Correlations between h[] and D[] */ 
                        /*          Normalized to 13 bits            */ 
) 
{ 
   Word16 i, j; 
   Word32 s, max, L_temp; 
   Word32 y32[L_SUBFR]; 
 
   /* first keep the result on 32 bits and find absolute maximum */ 
 
   max = 0; 
 
   for (i = 0; i < L_SUBFR; i++) 
   { 
     s = 0; 
     for (j = i; j <  L_SUBFR; j++) 
       s = L_mac(s, X[j], h[j-i]); 
 
     y32[i] = s; 
 
     s = L_abs(s); 
     L_temp =L_sub(s,max); 
     if(L_temp>0L) { 
        max = s; 
     } 
   } 
 
   /* Find the number of right shifts to do on y32[]  */ 
   /* so that maximum is on 13 bits                   */ 
 
   j = norm_l(max); 
   if( sub(j,16) > 0) { 
    j = 16; 
   } 
 
   j = sub(18, j); 
 
   for(i=0; i