/*                                                               v1.0 31.JUL.95  =============================================================================                          U    U   GGG    SSSS  TTTTT                          U    U  G       S       T                          U    U  G  GG   SSSS    T                          U    U  G   G       S   T                           UUU     GG     SSS     T                   ========================================                    ITU-T - USER'S GROUP ON SOFTWARE TOOLS                   ========================================MODULE:         IIR-FLAT.C, IIR FILTER MODULE, 		Sub-unit with flat low-pass IIR filteringORIGINAL BY:  Simao Ferraz de Campos Neto  Comsat Laboratories                  Tel:    +1-301-428-4516  22300 Comsat Drive                   Fax:    +1-301-428-9287  Clarksburg MD 20871 - USA            E-mail: simao@ctd.comsat.comDESCRIPTION:        This file contains functions for initializing and running an        IIR-filter (cascade form) with a low-pass characteristic for 3:1         and 1:3 rate change factors. FUNCTIONS    : - iir_casc_lp_3_to_1_init = init. of cascade-form IIR LP	       - fill_casc_iir_lp_3_to_1 = coeffs for cascade-form IIR LPHISTORY:    31.Jul.95 v1.0 Created <simao@ctd.comsat.com>  =============================================================================*//* General includes */#ifndef VMS#include <stdlib.h>		  /* General utility definitions */#endif#include <stdio.h>		  /* UNIX Standard I/O Definitions */#include <math.h>		  /* RTL Math Function Declarations *//* This module's prototypes */#include "iirflt.h"/* Local function prototypes */void fill_casc_iir_lp_3_to_1 ARGS((float ***a_cof, float ***b_cof, long *nblocks));/* External function prototypes - code in in iir-lib.c */extern CASCADE_IIR *cascade_iir_init ARGS((long nblocks, float (*a)[2], 			 float (*b)[2], double gain, long idown, int hswitch));/*  ============================================================================  void fill_casc_iir_lp_3_to_1 (float ***a_cof, float ***b_cof, long *nblocks);  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~  Description:  ~~~~~~~~~~~~  Initialize pointer to arrays with IIR coefficients for IIR flat band-pass   filter for rate change factor of 1:3/3:1. The coefficients used were   generated using Hypersignal for a ellyptic design and implemented in the   direct form II cascade. The filter has order 13 and have 7 sections.  Filtering is implemented using:                N             _______              -1        -2               | |  {  1  +  A1i z  +  A2i z  }       H(z)= K | |   --------------------------                i=1                -1        -2                    {  1  +  B1i z  +  B2i z  }  Parameters:  ~~~~~~~~~~~  float ***a_cof .. pointer to numerator filter coefficients  float ***b_cof .. pointer to denominator filter coefficients  long *nblocks ... number of coefficients (output value)  Return value:  None.  ~~~~~~~~~~~~~  Author: <simao@ctd.comsat.com>  ~~~~~~~  History:  ~~~~~~~~  30.Sep.94 v1.0 Release of 1st version <simao> ============================================================================*/void            fill_casc_iir_lp_3_to_1_ravi2(a_cof, b_cof, nblocks)  float        ***a_cof;  float        ***b_cof;  long           *nblocks;{#define nblocks_3_1        12	  /* number of 2'nd order blocks */  /* Numerator coefficients */  static float a_iir_3_1[nblocks_3_1][2] =                            { /*       z-1 ,      z-2 */			     {-1, 0},			     {-1.78633, 1},			     {-1.27455, 1},			     {-0.697086, 1},			     {-0.195802, 1},			     {0.191821, 1.00008},			     {0.476488, 1.00072},			     {0.684385, 0.99976},			     {0.814775, 0.993167},			     {1.01303, 1.00853},			     {0.955143, 1.03644},			     {0.980876, 0.98494},			   };  /* Denominator coefficients */  static float  b_iir_3_1[nblocks_3_1][2] =                           { /*  T[L]3   ,      T[L]4 */			     {-14.5254, 0},			     {-4.13681, 39.6786},			     {-0.128857, 12.0835},			     {0.751788, 5.96406},			     {1.07085, 1.38994},			     {1.0612, 3.72064},			     {1.08917, 1.05086},			     {1.14703, 2.0356},			     {1.22446, 2.71153},			     {1.24262, 1.03462},			     {1.46873, 1.38843},			     {1.49368, 1.94557},                           };#define gain_ravi2 4.0774e-06  *nblocks = nblocks_3_1;  *a_cof = (float **) a_iir_3_1;  *b_cof = (float **) b_iir_3_1;}#undef nblocks_3_1void            fill_casc_iir_lp_3_to_1_ravi1(a_cof, b_cof, nblocks)  float        ***a_cof;  float        ***b_cof;  long           *nblocks;{#define nblocks_3_1        12	  /* number of 2'nd order blocks */  /* Numerator coefficients */  static float a_iir_3_1[nblocks_3_1][2] =                            { /*       z-1 ,      z-2 */			     {-1, 0},			     {-1.78633, 0.999999},			     {-1.27455, 0.999999},			     {-0.697086, 1},			     {-0.195802, 1},			     {0.191806, 0.999921},			     {0.476144, 0.999278},			     {0.684549, 1.00024},			     {0.820381, 1.00688},			     {1.00447, 0.991547},			     {0.921565, 0.964845},			     {0.995874, 1.01529},			   };  /* Denominator coefficients */  static float  b_iir_3_1[nblocks_3_1][2] =                           { /*  T[L]3   ,      T[L]4 */			     {-14.5254, 0},			     {-0.104258, 0.0252025},			     {-0.0106639, 0.0827577},			     {0.126053, 0.167671},			     {0.770429, 0.719456},			     {0.28522, 0.268771},			     {1.03645, 0.951598},			     {0.563482, 0.491255},			     {0.451575, 0.368796},			     {1.20104, 0.966538},			     {1.05783, 0.720236},			     {0.767732, 0.513987}                           };  *nblocks = nblocks_3_1;  *a_cof = (float **) a_iir_3_1;  *b_cof = (float **) b_iir_3_1;}#undef nblocks_3_1void            fill_casc_iir_lp_3_to_1(a_cof, b_cof, nblocks)  float        ***a_cof;  float        ***b_cof;  long           *nblocks;{#define nblocks_3_1        7	  /* number of 2'nd order blocks */  /* Numerator coefficients */  static float a_iir_3_1[nblocks_3_1][2] =                            {  /*       z-1 ,      z-2 */			     {  1.00000000000,  0.00000000000 },			     { -1.08311748126,  1.00000000000 },			     { -1.04805345999,  1.00000000000 },			     { -0.956974481706, 1.00000000000 },			     {  0.859312578283, 1.00000000000 },			     { -0.748981579387, 1.00000000000 },			     { -0.261004187144, 1.00000000000 }			   };  /* Denominator coefficients */  static float  b_iir_3_1[nblocks_3_1][2] =                           { /*       z-1 ,      z-2 */			     { -0.741393933361, 0.000000000000 },			     { -1.44635266594,  0.599869375555 },			     { -1.36536866685,  0.711998423234 },			     { -1.28688150301,  0.822500869328 },			     { -1.23342027831,  0.902175203027 },			     { -1.20604048405,  0.952767955206 },			     { -1.20077042454,  0.986028477813 }                          };  *nblocks = nblocks_3_1;  *a_cof = (float **) a_iir_3_1;  *b_cof = (float **) b_iir_3_1;}#undef nblocks_3_1/* ..................... End of fill_casc_iir_lp_3_to_1() ..................... *//*  ============================================================================  CASCADE_IIR *iir_casc_lp_3_to_1_init (void);  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  Description:  ~~~~~~~~~~~~  Initialize a 8 kHz IIR filter structure for IRS (P.48) filtering.   Coefficients init'd by fill...() & gain furnished by Bellcore for the  ITU-T 8 kbit/s speech coder qualification tests.  Parameters:  none.  ~~~~~~~~~~~  Return value:  ~~~~~~~~~~~~~  Returns a pointer to struct CASCADE_IIR;    Author: <simao@ctd.comsat.com>  ~~~~~~~  History:  ~~~~~~~~  30.Sep.94 v1.0 Release of 1st version <simao> ============================================================================*/CASCADE_IIR        *iir_casc_lp_3_to_1_init(){  float         **a_cof, **b_cof; /* pointer to numerator/denominator */  long            nblocks;	  /* number of 2'nd order blocks */  fill_casc_iir_lp_3_to_1	      /* get pointer to filter-coefficients */    (&a_cof, &b_cof, &nblocks);  return cascade_iir_init(	  /* Returns: pointer to CASCADE_IIR-struct */			 nblocks, /* In: number of 2'nd order blocks */			 (float (*)[2]) a_cof,  /* Numerator. coef. */			 (float (*)[2]) b_cof,	/* Denom. coef. */			 2.552013334E-04,    /* In: gain factor for filter */			 (long) 3,           /* In: Down-sampling factor */			 'D');	             /* In: call down-sampl. routine */}/* ................... End of iir_casc_lp_3_to_1_init() ................... *//*  ============================================================================  CASCADE_IIR *iir_casc_lp_1_to_3_init (void);  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  Description:  ~~~~~~~~~~~~  Initialize a 8 kHz IIR filter structure for IRS (P.48) filtering.   Coefficients init'd by fill...() & gain furnished by Bellcore for the  ITU-T 8 kbit/s speech coder qualification tests.  Parameters:  none.  ~~~~~~~~~~~  Return value:  ~~~~~~~~~~~~~  Returns a pointer to struct CASCADE_IIR;    Author: <simao@ctd.comsat.com>  ~~~~~~~  History:  ~~~~~~~~  30.Sep.94 v1.0 Release of 1st version <simao> ============================================================================*/CASCADE_IIR        *iir_casc_lp_1_to_3_init(){  float         **a_cof, **b_cof; /* pointer to numerator/denominator */  long            nblocks;	  /* number of 2'nd order blocks */  fill_casc_iir_lp_3_to_1	      /* get pointer to filter-coefficients */    (&a_cof, &b_cof, &nblocks);  return cascade_iir_init(	  /* Returns: pointer to CASCADE_IIR-struct */			 nblocks, /* In: number of 2'nd order blocks */			 (float (*)[2]) a_cof,  /* Numerator. coef. */			 (float (*)[2]) b_cof,	/* Denom. coef. */			 3. * 2.552013334E-04, /* In: gain factor for filter */			 (long) 3,/* In: Up-sampling factor */			 'U');	  /* -> call up-sampling routine */}/* ................... End of iir_casc_lp_1_to_3_init() ................... *//* ************************** END OF IIR-FLAT.C *************************** */