view wdf/upsample.c @ 0:5242703e91d3 tip

Initial checkin for AIM92 aimR8.2 (last updated May 1997).

/*
    Copyright (c) Applied Psychology Unit, Medical Research Council. 1988, 1989
    ===========================================================================

    Permission to use, copy, modify, and distribute this software without fee 
    is hereby granted for research purposes, provided that this copyright 
    notice appears in all copies and in all supporting documentation, and that 
    the software is not redistributed for any fee (except for a nominal shipping 
    charge). Anyone wanting to incorporate all or part of this software in a
    commercial product must obtain a license from the Medical Research Council.

    The MRC makes no representations about the suitability of this 
    software for any purpose.  It is provided "as is" without express or implied 
    warranty.
 
    THE MRC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING 
    ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL THE
    A.P.U. BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY 
    DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN 
    AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

/*  
    Acknowledgment:
    ==============

    The source code provided in this file was originally developed by 
    Christian Giguere as part of a Ph.D degree at the Department of
    Engineering of the University of Cambridge from April 1990 to
    November 1993. The code was subsequently adapted under a grant
    from the Hearing Research Trust for full compatibility with 
    AIM Release 6.15.

    Christian Giguere 25/03/94

*/

/*
    ===========================================================
    upsample.c
    ===========================================================

    Upsampling module (FIR filter interpolation method).

    Author        : Christian Giguere
    First written : 23rd November, 1990 
    Last edited   : 09th February, 1994

    Reference:
    (1) L.R.Rabiner and R.W.Schafer (1978). Digital Processing of
	Speech Signals (Prentice-Hall), Section 2.4.2.
    ===========================================================
*/

/***** includes *****/

#include <math.h>
#include <stdio.h>
#include "stitch.h"
#include "source.h"
#include "calc.h"
#include "calc_tl.h"
#include "fir.h"
#include "upsample.h"


/***** defines *****/

#define   SEGMENT    ( 2048 )    /* number of new points allocated and retained */
				 /* on each call to input source */


/***** functions *****/

/*******************************************************************************
* name:                  function:
*
* upsample_callback()    Callable procedure returning pointer to upsampled data.  
* 
* UpSample()             Setup and initialization function for the design of an
*                        FIR interpolation filter. Returns pointer to a new source.
********************************************************************************/

struct _upsample_state {
  struct _fillable_source parent ;
  Source  source ; 
  Pointer input ; 
  int     iptr, inout_size ;
  int     zerocount, upsample_factor, sample_delay, active ;
  void    (*proc)(), (*close)() ;  
  FIRfilterState *states ;  
  } ;


/************************* upsample_callback() ******************************/

static Pointer upsample_callback( state, bytes, buffer )
  struct _upsample_state  *state ;
  ByteCount *bytes ;
  Pointer   buffer ;
{
  register DataType *optr, *eptr, *pstart ;
  register int      last = *bytes == 0 ;
  register int      points, bytecount ;   

 /***** process *****/
  if( !last ) {

     for( bytecount=0 ; bytecount<*bytes ; ) {

	/*** get input data ***/
	 points = ( *bytes - bytecount ) / state->inout_size ;
	 points = MIN( points, state->upsample_factor * SEGMENT ) ;

	 if( !state->active ) {

	     if( state->sample_delay == 0 )
		 state->active = 1 ;

	     else if( state->sample_delay > points )
		      state->sample_delay -= points ;

		  else {
		      points = state->sample_delay ;
		      state->sample_delay = 0 ;
		  }
	 }

	 if( state->iptr + ( points - 1 ) / state->upsample_factor >= SEGMENT ) {
	     state->input = Pull( state->source, SEGMENT * state->inout_size ) ;
	     state->iptr -= SEGMENT ;
	 }

	/*** fill output buffer with input points interspaced with zeros prior to FIR filtering ***/
	 pstart =  ( DataType * ) state->input ;       
	 optr = ( DataType * ) ( buffer + bytecount ) ;
	 eptr = optr + points ;

	 while( optr < eptr ) {
       
	     if( ( state->zerocount %= state->upsample_factor ) > 0 ) 
		 *optr++ = 0 ;

	     else
		 *optr++ = pstart[state->iptr++] ; 

	     state->zerocount++ ; 
	 }

	/*** filter data ***/
	 state->proc( state->states, buffer+bytecount, points ) ; 
	    
	/*** loop counts ***/ 
	 bytecount += points * state->inout_size * state->active ;
     }

     return ( buffer ) ;
  }


 /***** close *****/
  else {
     Pull( state->source, 0 ) ;
     state->close( state->states ) ;

     return ( DeleteFillableSource( state ) ) ;
  }

}


/****************************** UpSample() **********************************/

Source UpSample( source, oldsamplerate, cutoff_freq, upsample_factor )
  Source source ;
  double oldsamplerate, cutoff_freq ;
  int    upsample_factor ;
{
  DeclareNew( struct _upsample_state *, state ) ;
  double filterGain, wc ;

 /***** initialise input-related parameters *****/
  state->inout_size = sizeof ( DataType ) ;
  state->input  = ( Pointer ) 0 ;
  state->iptr = SEGMENT ;
  state->source = NewRetainingSource( source, SEGMENT * state->inout_size ) ;
  state->zerocount = 0 ;
  state->upsample_factor = upsample_factor ;    

 /***** Specify FIR filter design parameters *****/
  wc = cutoff_freq / ( state->upsample_factor * oldsamplerate ) * TwoPi ;
  state->states = NewLpFIRfilter( wc, upsample_factor, &state->sample_delay ) ; 
  state->active = 0 ;
  state->proc = DoFIRfilter ;
  state->close = CloseFIRfilter ;

 /***** return *****/
  source = SetFillableSource( state, upsample_callback, "upsample buffering" ) ;
  return ( source ) ;

}