tomwalters@0: /*
tomwalters@0:     Copyright (c) Applied Psychology Unit, Medical Research Council. 1988, 1989
tomwalters@0:     ===========================================================================
tomwalters@0: 
tomwalters@0:     Permission to use, copy, modify, and distribute this software without fee 
tomwalters@0:     is hereby granted for research purposes, provided that this copyright 
tomwalters@0:     notice appears in all copies and in all supporting documentation, and that 
tomwalters@0:     the software is not redistributed for any fee (except for a nominal shipping 
tomwalters@0:     charge). Anyone wanting to incorporate all or part of this software in a
tomwalters@0:     commercial product must obtain a license from the Medical Research Council.
tomwalters@0: 
tomwalters@0:     The MRC makes no representations about the suitability of this 
tomwalters@0:     software for any purpose.  It is provided "as is" without express or implied 
tomwalters@0:     warranty.
tomwalters@0:  
tomwalters@0:     THE MRC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING 
tomwalters@0:     ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL THE
tomwalters@0:     A.P.U. BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY 
tomwalters@0:     DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN 
tomwalters@0:     AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 
tomwalters@0:     OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
tomwalters@0: */
tomwalters@0: 
tomwalters@0: /*  
tomwalters@0:     Acknowledgment:
tomwalters@0:     ==============
tomwalters@0: 
tomwalters@0:     The source code provided in this file was originally developed by 
tomwalters@0:     Christian Giguere as part of a Ph.D degree at the Department of
tomwalters@0:     Engineering of the University of Cambridge from April 1990 to
tomwalters@0:     November 1993. The code was subsequently adapted under a grant
tomwalters@0:     from the Hearing Research Trust for full compatibility with 
tomwalters@0:     AIM Release 6.15.
tomwalters@0: 
tomwalters@0:     Christian Giguere 25/03/94
tomwalters@0: 
tomwalters@0: */
tomwalters@0: 
tomwalters@0: /*
tomwalters@0:     ===========================================================
tomwalters@0:     upsample.c
tomwalters@0:     ===========================================================
tomwalters@0: 
tomwalters@0:     Upsampling module (FIR filter interpolation method).
tomwalters@0: 
tomwalters@0:     Author        : Christian Giguere
tomwalters@0:     First written : 23rd November, 1990 
tomwalters@0:     Last edited   : 09th February, 1994
tomwalters@0: 
tomwalters@0:     Reference:
tomwalters@0:     (1) L.R.Rabiner and R.W.Schafer (1978). Digital Processing of
tomwalters@0: 	Speech Signals (Prentice-Hall), Section 2.4.2.
tomwalters@0:     ===========================================================
tomwalters@0: */
tomwalters@0: 
tomwalters@0: /***** includes *****/
tomwalters@0: 
tomwalters@0: #include <math.h>
tomwalters@0: #include <stdio.h>
tomwalters@0: #include "stitch.h"
tomwalters@0: #include "source.h"
tomwalters@0: #include "calc.h"
tomwalters@0: #include "calc_tl.h"
tomwalters@0: #include "fir.h"
tomwalters@0: #include "upsample.h"
tomwalters@0: 
tomwalters@0: 
tomwalters@0: /***** defines *****/
tomwalters@0: 
tomwalters@0: #define   SEGMENT    ( 2048 )    /* number of new points allocated and retained */
tomwalters@0: 				 /* on each call to input source */
tomwalters@0: 
tomwalters@0: 
tomwalters@0: /***** functions *****/
tomwalters@0: 
tomwalters@0: /*******************************************************************************
tomwalters@0: * name:                  function:
tomwalters@0: *
tomwalters@0: * upsample_callback()    Callable procedure returning pointer to upsampled data.  
tomwalters@0: * 
tomwalters@0: * UpSample()             Setup and initialization function for the design of an
tomwalters@0: *                        FIR interpolation filter. Returns pointer to a new source.
tomwalters@0: ********************************************************************************/
tomwalters@0: 
tomwalters@0: struct _upsample_state {
tomwalters@0:   struct _fillable_source parent ;
tomwalters@0:   Source  source ; 
tomwalters@0:   Pointer input ; 
tomwalters@0:   int     iptr, inout_size ;
tomwalters@0:   int     zerocount, upsample_factor, sample_delay, active ;
tomwalters@0:   void    (*proc)(), (*close)() ;  
tomwalters@0:   FIRfilterState *states ;  
tomwalters@0:   } ;
tomwalters@0: 
tomwalters@0: 
tomwalters@0: /************************* upsample_callback() ******************************/
tomwalters@0: 
tomwalters@0: static Pointer upsample_callback( state, bytes, buffer )
tomwalters@0:   struct _upsample_state  *state ;
tomwalters@0:   ByteCount *bytes ;
tomwalters@0:   Pointer   buffer ;
tomwalters@0: {
tomwalters@0:   register DataType *optr, *eptr, *pstart ;
tomwalters@0:   register int      last = *bytes == 0 ;
tomwalters@0:   register int      points, bytecount ;   
tomwalters@0: 
tomwalters@0:  /***** process *****/
tomwalters@0:   if( !last ) {
tomwalters@0: 
tomwalters@0:      for( bytecount=0 ; bytecount<*bytes ; ) {
tomwalters@0: 
tomwalters@0: 	/*** get input data ***/
tomwalters@0: 	 points = ( *bytes - bytecount ) / state->inout_size ;
tomwalters@0: 	 points = MIN( points, state->upsample_factor * SEGMENT ) ;
tomwalters@0: 
tomwalters@0: 	 if( !state->active ) {
tomwalters@0: 
tomwalters@0: 	     if( state->sample_delay == 0 )
tomwalters@0: 		 state->active = 1 ;
tomwalters@0: 
tomwalters@0: 	     else if( state->sample_delay > points )
tomwalters@0: 		      state->sample_delay -= points ;
tomwalters@0: 
tomwalters@0: 		  else {
tomwalters@0: 		      points = state->sample_delay ;
tomwalters@0: 		      state->sample_delay = 0 ;
tomwalters@0: 		  }
tomwalters@0: 	 }
tomwalters@0: 
tomwalters@0: 	 if( state->iptr + ( points - 1 ) / state->upsample_factor >= SEGMENT ) {
tomwalters@0: 	     state->input = Pull( state->source, SEGMENT * state->inout_size ) ;
tomwalters@0: 	     state->iptr -= SEGMENT ;
tomwalters@0: 	 }
tomwalters@0: 
tomwalters@0: 	/*** fill output buffer with input points interspaced with zeros prior to FIR filtering ***/
tomwalters@0: 	 pstart =  ( DataType * ) state->input ;       
tomwalters@0: 	 optr = ( DataType * ) ( buffer + bytecount ) ;
tomwalters@0: 	 eptr = optr + points ;
tomwalters@0: 
tomwalters@0: 	 while( optr < eptr ) {
tomwalters@0:        
tomwalters@0: 	     if( ( state->zerocount %= state->upsample_factor ) > 0 ) 
tomwalters@0: 		 *optr++ = 0 ;
tomwalters@0: 
tomwalters@0: 	     else
tomwalters@0: 		 *optr++ = pstart[state->iptr++] ; 
tomwalters@0: 
tomwalters@0: 	     state->zerocount++ ; 
tomwalters@0: 	 }
tomwalters@0: 
tomwalters@0: 	/*** filter data ***/
tomwalters@0: 	 state->proc( state->states, buffer+bytecount, points ) ; 
tomwalters@0: 	    
tomwalters@0: 	/*** loop counts ***/ 
tomwalters@0: 	 bytecount += points * state->inout_size * state->active ;
tomwalters@0:      }
tomwalters@0: 
tomwalters@0:      return ( buffer ) ;
tomwalters@0:   }
tomwalters@0: 
tomwalters@0: 
tomwalters@0:  /***** close *****/
tomwalters@0:   else {
tomwalters@0:      Pull( state->source, 0 ) ;
tomwalters@0:      state->close( state->states ) ;
tomwalters@0: 
tomwalters@0:      return ( DeleteFillableSource( state ) ) ;
tomwalters@0:   }
tomwalters@0: 
tomwalters@0: }
tomwalters@0: 
tomwalters@0: 
tomwalters@0: /****************************** UpSample() **********************************/
tomwalters@0: 
tomwalters@0: Source UpSample( source, oldsamplerate, cutoff_freq, upsample_factor )
tomwalters@0:   Source source ;
tomwalters@0:   double oldsamplerate, cutoff_freq ;
tomwalters@0:   int    upsample_factor ;
tomwalters@0: {
tomwalters@0:   DeclareNew( struct _upsample_state *, state ) ;
tomwalters@0:   double filterGain, wc ;
tomwalters@0: 
tomwalters@0:  /***** initialise input-related parameters *****/
tomwalters@0:   state->inout_size = sizeof ( DataType ) ;
tomwalters@0:   state->input  = ( Pointer ) 0 ;
tomwalters@0:   state->iptr = SEGMENT ;
tomwalters@0:   state->source = NewRetainingSource( source, SEGMENT * state->inout_size ) ;
tomwalters@0:   state->zerocount = 0 ;
tomwalters@0:   state->upsample_factor = upsample_factor ;    
tomwalters@0: 
tomwalters@0:  /***** Specify FIR filter design parameters *****/
tomwalters@0:   wc = cutoff_freq / ( state->upsample_factor * oldsamplerate ) * TwoPi ;
tomwalters@0:   state->states = NewLpFIRfilter( wc, upsample_factor, &state->sample_delay ) ; 
tomwalters@0:   state->active = 0 ;
tomwalters@0:   state->proc = DoFIRfilter ;
tomwalters@0:   state->close = CloseFIRfilter ;
tomwalters@0: 
tomwalters@0:  /***** return *****/
tomwalters@0:   source = SetFillableSource( state, upsample_callback, "upsample buffering" ) ;
tomwalters@0:   return ( source ) ;
tomwalters@0: 
tomwalters@0: }
tomwalters@0: