lpc10/irc2pc.c

   1 /*
   2
   3  * Revision 1.1  1996/08/19  22:31:56  jaf
   4  * Initial revision
   5  *
   6
   7 */
   8
   9 /*  -- translated by f2c (version 19951025).
  10    You must link the resulting object file with the libraries:
  11         -lf2c -lm   (in that order)
  12 */
  13
  14 #include "f2c.h"
  15
  16 extern int irc2pc_(real *rc, real *pc, integer *order, real *gprime, real *g2pass);
  17
  18 /* ***************************************************************** */
  19
  20 /*      IRC2PC Version 48 */
  21
  22 /*
  23  * Revision 1.1  1996/08/19  22:31:56  jaf
  24  * Initial revision
  25  * */
  26 /* Revision 1.3  1996/03/20  15:47:19  jaf */
  27 /* Added comments about which indices of array arguments are read or */
  28 /* written. */
  29
  30 /* Revision 1.2  1996/03/14  16:59:04  jaf */
  31 /* Comments added explaining that none of the local variables of this */
  32 /* subroutine need to be saved from one invocation to the next. */
  33
  34 /* Revision 1.1  1996/02/07 14:47:27  jaf */
  35 /* Initial revision */
  36
  37
  38 /* ***************************************************************** */
  39
  40 /*   Convert Reflection Coefficients to Predictor Coeficients */
  41
  42 /* Inputs: */
  43 /*  RC     - Reflection coefficients */
  44 /*           Indices 1 through ORDER read. */
  45 /*  ORDER  - Number of RC's */
  46 /*  GPRIME - Excitation modification gain */
  47 /* Outputs: */
  48 /*  PC     - Predictor coefficients */
  49 /*           Indices 1 through ORDER written. */
  50 /*           Indices 1 through ORDER-1 are read after being written. */
  51 /*  G2PASS - Excitation modification sharpening factor */
  52
  53 /* This subroutine has no local state. */
  54
  55 /* Subroutine */ int irc2pc_(real *rc, real *pc, integer *order, real *gprime,
  56          real *g2pass)
  57 {
  58     /* System generated locals */
  59     integer i__1, i__2;
  60
  61     /* Builtin functions */
  62     double sqrt(doublereal);
  63
  64     /* Local variables */
  65     real temp[10];
  66     integer i__, j;
  67
  68 /*      Arguments */
  69 /*   LPC Configuration parameters: */
  70 /* Frame size, Prediction order, Pitch period */
  71 /*       Local variables that need not be saved */
  72     /* Parameter adjustments */
  73     --pc;
  74     --rc;
  75
  76     /* Function Body */
  77     *g2pass = 1.f;
  78     i__1 = *order;
  79     for (i__ = 1; i__ <= i__1; ++i__) {
  80         *g2pass *= 1.f - rc[i__] * rc[i__];
  81     }
  82     *g2pass = *gprime * sqrt(*g2pass);
  83     pc[1] = rc[1];
  84     i__1 = *order;
  85     for (i__ = 2; i__ <= i__1; ++i__) {
  86         i__2 = i__ - 1;
  87         for (j = 1; j <= i__2; ++j) {
  88             temp[j - 1] = pc[j] - rc[i__] * pc[i__ - j];
  89         }
  90         i__2 = i__ - 1;
  91         for (j = 1; j <= i__2; ++j) {
  92             pc[j] = temp[j - 1];
  93         }
  94         pc[i__] = rc[i__];
  95     }
  96     return 0;
  97 } /* irc2pc_ */
  98