/*                                                         v1.0 28.FEB.92 18H00  =============================================================================                          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-G712.C, IIR FILTER MODULE,                 Sub-unit with the parallel-form standard PCM filter (G.712)ORIGINAL BY:                Rudolf Hofmann                Advanced Development Digital Signal Processing                PHILIPS KOMMUNIKATIONS INDUSTRIE AG                Kommunikationssysteme                Thurn-und-Taxis-Strasse 14                D-8500 Nuernberg 10 (Germany)                Phone : +49 911 526-2603                FAX   : +49 911 526-3385                EMail : hf@pkinbg.uucpDESCRIPTION:        This file contains functions for initializing an        IIR-filter (parallel form) with a standard PCM frequency        response (sampling frequency = 8 and16 kHz).        (see also ETSI-document TD 91/23, 4.2).FUNCTIONS    : - stdpcm_16khz_init()  =  initialization of standard                                         PCM-filter for sf=16kHz               - stdpcm_1_to_2_init() =  as "stdpcm_16khz_init()", but                                         needs input with sf=8kHz and                                         returns data with sf=16 kHz               - stdpcm_2_to_1_init() =  as "stdpcm_16khz_init()", but                                         needs input with sf=16kHz and                                         returns data with sf=8 kHzHISTORY:    16.Dec.91 v0.1 First beta-version <hf@pkinbg.uucp>    28.Feb.92 v1.0 Release of 1st version to UGST <hf@pkinbg.uucp>    30.Oct.94 v2.0 Broken into sub-units. <simao@ctd.comsat.com>  =============================================================================*//* * ......... INCLUDES ......... */#ifndef VMS#include <stdlib.h>		  /* General utility definitions */#endif#include <math.h>		  /* RTL Math Function Declarations *//* Definitions for IIR filters */#include "iirflt.h"		  /* * ......... Local function *smart* prototypes ......... */void fill_iir_cof_16khz ARGS((float ***b_cof, float ***c_cof, 			      double *K, long *nblocks));/* External function prototypes - code in in iir-lib.c */extern SCD_IIR *scd_stdpcm_init ARGS((long nblocks, float (*b)[3], 			    float (*c)[2], double direct_cof, double gain, 			    long idown, int hswitch));/* * ...................... BEGIN OF FUNCTIONS ......................... *//*  ============================================================================        SCD_IIR *stdpcm_16khz_init (void);        ~~~~~~~~~~~~~~~~~~~~~~~~~~        Description:        ~~~~~~~~~~~~        Initialize a 16 kHz IIR filter structure for standard PCM (G712)        filtering.        Parameters:  none.        ~~~~~~~~~~~        Return value:        ~~~~~~~~~~~~~        Returns a pointer to struct SCD_IIR;        Author: <hf@pkinbg.uucp>        ~~~~~~~        History:        ~~~~~~~~        28.Feb.92 v1.0 Release of 1st version <hf@pkinbg.uucp> ============================================================================*/SCD_IIR        *stdpcm_16khz_init(){  float         **b_cof, **c_cof; /* pointer to numerator/denominator */  double          K;		  /* coefficients; direct path coef. */  long            nblocks;	  /* number of 2'nd order blocks */  /* get pointer to filter-coefficients */  fill_iir_cof_16khz(&b_cof, &c_cof, &K, &nblocks);  /* Returns: pointer to SCD_IIR-struct */  return scd_stdpcm_init(nblocks, /* In: number of 2'nd order blocks */			 (float (*)[3]) b_cof,	/* In: 24-bit repres. of						 * numer. coef. */			 (float (*)[2]) c_cof,	/* In: 24-bit repres. of						 * denom. coef. */			 K,	  /* 'K' (direct path coefficient) */			 1.0,	  /* In: gain factor for filter */			 (long) 1,/* In: Down-sampling factor */			 'D');	  /* -> call down-sampling routine */}/* ....................... End of stdpcm_16khz_init() ....................... *//*  ============================================================================        SCD_IIR *stdpcm_2_to_1_init (void);        ~~~~~~~~~~~~~~~~~~~~~~~~~~~        Description:        ~~~~~~~~~~~~        Initialize Standard PCM-Filter sampling frequencies for        "stdpcm_kernel":         -  input signal: 16 kHz         -  output signal: 8 kHz        Parameters:  none.        ~~~~~~~~~~~        Return value:        ~~~~~~~~~~~~~        Returns a pointer to struct SCD_IIR;        Author: <hf@pkinbg.uucp>        ~~~~~~~        History:        ~~~~~~~~        28.Feb.92 v1.0 Release of 1st version <hf@pkinbg.uucp> ============================================================================*/SCD_IIR        *stdpcm_2_to_1_init(){  float         **b_cof, **c_cof; /* pointer to numerator/denominator */  double          K;		  /* coefficients; direct path coef. */  long            nblocks;	  /* number of 2'nd order blocks */  fill_iir_cof_16khz		  /* get pointer to filter-coefficients */    (&b_cof, &c_cof, &K, &nblocks);	/* */  return    scd_stdpcm_init(		  /* Returns: pointer to SCD_IIR-struct */		    nblocks,	  /* In: number of 2'nd order blocks */		    (float (*)[3]) b_cof,	/* In: 24-bit repres. of						 * numer. coef. */		    (float (*)[2]) c_cof,	/* In: 24-bit repres. of						 * denom. coef. */		    K,		  /* 'K' (direct path coefficient) */		    1.0,	  /* In: gain factor for filter */		    (long) 2,	  /* In: Down-sampling factor */		    'D'		  /* -> call down-sampling routine */    );}/* ..................... End of stdpcm_2_to_1_init() ..................... *//*  ============================================================================        SCD_IIR *stdpcm_1_to_2_init (void);        ~~~~~~~~~~~~~~~~~~~~~~~~~~~        Description:        ~~~~~~~~~~~~        Initialize Standard PCM-Filter sampling frequencies for        "stdpcm_kernel":         -  input signal:   8 kHz         -  output signal: 16 kHz        Parameters:  none.        ~~~~~~~~~~~        Return value:        ~~~~~~~~~~~~~        Returns a pointer to struct SCD_IIR;        Author: <hf@pkinbg.uucp>        ~~~~~~~        History:        ~~~~~~~~        28.Feb.92 v1.0 Release of 1st version <hf@pkinbg.uucp> ============================================================================*/SCD_IIR        *stdpcm_1_to_2_init(){  float         **b_cof, **c_cof; /* pointer to numerator/denominator */  double          K;		  /* coefficients; direct path coef. */  long            nblocks;	  /* number of 2'nd order blocks */  /* get pointer to filter-coefficients */  fill_iir_cof_16khz(&b_cof, &c_cof, &K, &nblocks);  return    scd_stdpcm_init(		  /* Returns: pointer to SCD_IIR-struct */		    nblocks,	  /* In: number of 2'nd order blocks */		    (float (*)[3]) b_cof,	/* In: 24-bit repres. of						 * numer. coef. */		    (float (*)[2]) c_cof,	/* In: 24-bit repres. of						 * denom. coef. */		    K,		  /* 'K' (direct path coefficient) */		    2.0,	  /* In: gain factor for filter */		    (long) 2,	  /* In: Up-sampling factor */		    'U'		  /* -> call up-sampling routine */    );}/* ...................... End of stdpcm_1_to_2_init() ...................... *//*  ============================================================================        SCD_IIR *fill_iir_cof_16khz ();        ~~~~~~~~~~~~~~~~~~~~~~~~~~~        Description:        ~~~~~~~~~~~~        Return pointer to arrays with IIR coefficients for standard PCM        filter, running at 16 kHz.        Parameters:        ~~~~~~~~~~~        float ***b_cof .. pointer to numerator filter coefficients        float ***c_cof .. pointer to denominator filter coefficients        double *K ....... 'K' (direct path coefficient)        long *nblocks ... number of coefficients (output value)        Return value:  None.        ~~~~~~~~~~~~~        Author: <hf@pkinbg.uucp>        ~~~~~~~        History:        ~~~~~~~~        28.Feb.92 v1.0 Release of 1st version <hf@pkinbg.uucp> ============================================================================*/void            fill_iir_cof_16khz(b_cof, c_cof, K, nblocks)  float        ***b_cof;  float        ***c_cof;  double         *K;  long           *nblocks;{#define nblocks_16khz        4	  /* number of 2'nd order blocks */#define f24                  (float)0x00800000#define K_direct_path_16khz  -0.620901	/* 'K' (direct path coefficient) */  /* Numerator coefficients */  static float b_16khz[4][3] =                            { /*       T[L]1   ,      T[L]2 */                            { 0.,  1990214./f24, -4831226./f24},                            { 0., - 891214./f24,   390775./f24},                            { 0.,   188047./f24, - 190086./f24},                            { 0., -7026995./f24,  7461919./f24}                           };  /* (Denominator coefficients) */  static float  c_16khz[4][2] =                           { /*  T[L]3   ,      T[L]4 */                            { 1599397./f24, -2059789./f24},                            { 3376264./f24, -1250280./f24},                            { 4020626./f24, -8195142./f24},                            { 1243410./f24, -5159623./f24}                           };  *nblocks = nblocks_16khz;  *b_cof = (float **) b_16khz;  *c_cof = (float **) c_16khz;  *K = K_direct_path_16khz;}#undef K_direct_path_16khz#undef f24#undef nblocks_16khz/* ...................... End of fill_iir_cof_16khz() ...................... *//* ************************** END OF IIR-G712.C *************************** */