www.pudn.com > CryptoPhone-src-031122.zip > filters.c

/* Copyright 2001,2002,2003 NAH6 
 * All Rights Reserved 
 * 
 * Parts Copyright DoD, Parts Copyright Starium 
 * 
 */ 
/*#include "main.h"*/ 
#include "celpfilt.h" 
#include "movarray.h" 
#include "setarray.h" 
 
/* LP Analysis Filter Parameters */ 
FILTER	InputHPFZ, InputHPFP; 
float 	InputHPFCoefsZ[3] = {0.946, -1.892, 0.946}; 
float 	InputHPFCoefsP[3] = {1.0, -1.889033, 0.8948743}; 
int	InputHPFOrder = 2; 
int	InputHPFLength = F_LEN; 
 
/* LP residual calculation filter parameters */ 
FILTER	LP_ResZ, LP_ResP, LP_ResP2; 
 
/* Adaptive analysis residual calculation filter parameters */ 
FILTER	Adapt_ResZ, Adapt_ResP, Adapt_ResP2; 
 
/* Update filters for residual calculations */ 
FILTER	Update_ResZ, Update_ResP, Update_ResP2; 
 
/*  HPF output filters for synthesis */ 
FILTER	OutputHPFZ, OutputHPFP; 
/*  Filter coefficients for 2nd order Butterworth 275 Hz HPF:		*/ 
float	OutputHPFCoefsZ[3] = {0.946, -1.892, 0.946}; 
float 	OutputHPFCoefsP[3] = {1.0, -1.889033, 0.8948743}; 
 
/* 
 
************************************************************************* 
*                                                                         * 
* ROUTINE 
*		HPF_Speech 
* 
* FUNCTION 
*		High pass filter input speech 
* SYNOPSIS 
*		HPF_Speech(speech_in) 
* 
*   formal 
* 
*                       data    I/O 
*       name            type    type    function 
*       ------------------------------------------------------------------- 
*	speech_in	float	 i/o	Frame of input speech 
* 
**************************************************************************/ 
 
void HPF_InSpeech( 
float	speech[F_LEN]) 
{ 
 
	do_zfilt(&InputHPFZ, speech); 
	do_pfilt(&InputHPFP, speech); 
 
} 
 
 
/* 
 
************************************************************************* 
*                                                                         * 
* ROUTINE 
*		HPF_OutSpeech 
* 
* FUNCTION 
*		High pass filter output speech 
* SYNOPSIS 
*		HPF_Outspeech(speech_in, speech_out) 
* 
*   formal 
* 
*                       data    I/O 
*       name            type    type    function 
*       ------------------------------------------------------------------- 
*	speech_in	float	  i	Frame of input speech 
*	speech_in	float	  o	Frame of output speech 
* 
**************************************************************************/ 
 
void HPF_OutSpeech( 
float	speech_in[SF_LEN], 
float	speech_out[SF_LEN]) 
{ 
 
/*  Perform filtering on input speech to produce output speech */ 
	MoveArray(SF_LEN, speech_in, speech_out); 
	do_zfilt(&OutputHPFZ, speech_out); 
	do_pfilt(&OutputHPFP, speech_out); 
 
} 
 
 
/* 
 
************************************************************************* 
*                                                                         * 
* ROUTINE 
*		FilterImpulseResponse 
* 
* FUNCTION 
*		Filter Impulse Response with varying coefficients and 
		  no history from past frames 
* SYNOPSIS 
*		FilterImpulseResponse(h, coef) 
* 
*   formal 
* 
*                       data    I/O 
*       name            type    type    function 
*       ------------------------------------------------------------------- 
*	h		float	 i/o	Impulse response 
*	coef		float	  i	Filter coefficients 
* 
**************************************************************************/ 
 
void FilterImpulseResponse( 
float	h[SF_LEN], 
float	coef[ORDER+1]) 
{ 
int	t, j; 
float	FiltMem[ORDER+1]; 
 
/*  Initialize memory */ 
	SetArray(ORDER+1, 0.0, FiltMem); 
	 
/*  Filter impulse response */ 
	for(t=0; t0; j--)	{ 
	    FiltMem[0] -= coef[j] * FiltMem[j]; 
	    FiltMem[j]  = FiltMem[j-1]; 
	  } 
	  h[t] = FiltMem[0]; 
	} 
}