tomwalters@0: /*
tomwalters@0:     Copyright (c) Applied Psychology Unit, Medical Research Council. 1994
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:     bank_tl.c
tomwalters@0:     ===========================================================
tomwalters@0: 
tomwalters@0:     Design of cochlear transmission line filterbank (TLF) with
tomwalters@0:     coupled outer ear and middle ear (EAR) filter.
tomwalters@0: 
tomwalters@0:     Author        : Christian Giguere
tomwalters@0:     First written : 01st April, 1991
tomwalters@0:     Last edited   : 07th March, 1994
tomwalters@0:     
tomwalters@0:     Reference:
tomwalters@0:     (1) C.Giguere and P.C.Woodland (1994). JASA 95(1): 331-342.
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 "wdf_tl.h"
tomwalters@0: #include "formulae.h"
tomwalters@0: #include "formulae_tl.h"
tomwalters@0: #include "scales.h"
tomwalters@0: #include "scales_tl.h"
tomwalters@0: #include "bank.h"
tomwalters@0: #include "bank_tl.h"
tomwalters@0: #include "ear.h"     
tomwalters@0: #include "wdf_ear.h"
tomwalters@0:      
tomwalters@0: /***** defines *****/
tomwalters@0: 
tomwalters@0: #if 0
tomwalters@0: #define  _DEBUG_ 
tomwalters@0: #endif
tomwalters@0: 
tomwalters@0: #define   MIN_CF        (     16.0 )     /* Minimum BM segment CF allowed (Hz) */
tomwalters@0: #define   MAX_CF        (  15000.0 )     /* Maximum BM segment CF allowed (Hz) */
tomwalters@0: #define   REF_CF        (   1000.0 )     /* Reference CF (Hz) for scaling BM output and Q factor */
tomwalters@0: #define   L             (      3.5 )     /* Length of BM (cm) */
tomwalters@0: #define   MinLength     (   1.0E-6 )     /* Mininum length of each BM segment (cm) */
tomwalters@0: #define   B0            (    0.015 )     /* BM width at basal end (cm) */
tomwalters@0: #define   B_exp         (     0.30 )     /* Exponential constant for BM width (1/cm) */
tomwalters@0: #define   A0            (     0.03 )     /* Cross-sectional area of each scala at basal end (cm2) */
tomwalters@0: #define   A_exp         (    -0.60 )     /* Exponential constant for scalea cross-sectional area (1/cm) */
tomwalters@0: #define   RHO_fluid     (      1.0 )     /* Density of cochlear fluids [g/cm3] */
tomwalters@0: #define   MASS_PER_AREA (    0.015 )     /* Transerval mass per area of basilar membrane (g/cm2) */
tomwalters@0: #define   Q_CHANNEL     (        0 )     /* Introduce channel-dependent Q factor */
tomwalters@0: #define   RATIO         (     30.0 )     /* Transformer ratio between oval window and eardrum */
tomwalters@0: #define   WARPING       (        0 )     /* Compensate frequency warping of bilinear transform */
tomwalters@0: 
tomwalters@0: 
tomwalters@0: /***** externals */
tomwalters@0: 
tomwalters@0: extern Source InterpSource() ;
tomwalters@0: 
tomwalters@0: /***** functions *****/
tomwalters@0: 
tomwalters@0: /**************************************************************************
tomwalters@0: * name:                    function:
tomwalters@0: *
tomwalters@0: * tlf_bank_callback()      Callable procedure returning pointer to filtered
tomwalters@0: *                          data (BM velocity or displacement).
tomwalters@0: *
tomwalters@0: * TLF_GenBank()            Set-up and initialization function for the design 
tomwalters@0: *                          of the cochlear filterbank. Returns pointer to
tomwalters@0: *                          a new source.  
tomwalters@0: ***************************************************************************/
tomwalters@0: 
tomwalters@0: typedef struct _bank_segment  BankSegment ;
tomwalters@0: 
tomwalters@0: struct _bank_segment {
tomwalters@0:   double  center_frequency ;
tomwalters@0:   double  seglength, position ;
tomwalters@0:   int     active ;
tomwalters@0:   } ;
tomwalters@0: 
tomwalters@0: struct _tlf_bank_state {
tomwalters@0:   struct           _fillable_source parent ;
tomwalters@0:   Source           source ; 
tomwalters@0:   Pointer          input ; 
tomwalters@0:   int              inout_size ;
tomwalters@0:   void             (*proc)(), (*closeEar)(), (*closeTLF)() ;
tomwalters@0:   int              total_chans, display_chans ;
tomwalters@0:   TLF_BankInfo     *bank ;
tomwalters@0:   WDFilterState    **states ;
tomwalters@0:   int              Ntube ;
tomwalters@0:   WaveWDFstate     *wave_states ;
tomwalters@0:   EartubeWDFstate  **eartube_states ;
tomwalters@0:   EarmiddleWDFstate *earmiddle_states ;
tomwalters@0:   } ;
tomwalters@0: 
tomwalters@0: 
tomwalters@0: /************************* tlf_bank_callback() ****************************/
tomwalters@0: 
tomwalters@0: static Pointer tlf_bank_callback( state, bytes, buffer )
tomwalters@0: struct _tlf_bank_state *state ;
tomwalters@0: ByteCount *bytes ;
tomwalters@0: Pointer   buffer ;
tomwalters@0: {
tomwalters@0:     register TLF_BankInfo *bankInfo = state->bank ;
tomwalters@0:     register int          last = *bytes == 0 ;
tomwalters@0:     register int          points ;
tomwalters@0:     register ByteCount    bytecount ;
tomwalters@0: 
tomwalters@0:    /***** process *****/
tomwalters@0:     if( !last ) {
tomwalters@0: 
tomwalters@0: 	points = *bytes * bankInfo->decimate_factor / 
tomwalters@0: 		 ( state->display_chans * state->inout_size ) ;
tomwalters@0: 
tomwalters@0: 	state->input = Pull( state->source, points * state->inout_size ) ;
tomwalters@0: 
tomwalters@0: 	state->proc( bankInfo, state->states, state->input, buffer, points, 
tomwalters@0: 		     state->total_chans, state->wave_states, state->eartube_states,
tomwalters@0: 		     state->earmiddle_states, state->Ntube ) ;
tomwalters@0: 
tomwalters@0: 	return ( buffer ) ;
tomwalters@0:     }
tomwalters@0: 
tomwalters@0:    /***** close *****/
tomwalters@0:     else {
tomwalters@0: 
tomwalters@0: 	Pull( state->source, 0 ) ;
tomwalters@0: 	state->closeEar( state->wave_states, state->eartube_states, state->earmiddle_states, state->Ntube ) ;
tomwalters@0: 	state->closeTLF( state->states, state->total_chans, state->bank ) ;
tomwalters@0: 
tomwalters@0: 	return ( DeleteFillableSource( state ) ) ;  
tomwalters@0:      }
tomwalters@0: }
tomwalters@0: 
tomwalters@0: 
tomwalters@0: /************************** TLF_GenBank() *****************************/
tomwalters@0: 
tomwalters@0: Source TLF_GenBank( source, interps, info, chans, decimate_factor, samplerate, center_frequencies, 
tomwalters@0: 		    output_gain, outdens, qbase, OHC_gain, OHC_sat, motionstr, concha, canal )
tomwalters@0: Source source ;
tomwalters@0: int    interps, info, *chans, *decimate_factor ;
tomwalters@0: double samplerate, *center_frequencies, output_gain, outdens ;
tomwalters@0: double qbase, OHC_gain, OHC_sat ;
tomwalters@0: char   *motionstr ;
tomwalters@0: TubeInfo *concha, *canal ;
tomwalters@0: {
tomwalters@0:     DeclareNew( struct _tlf_bank_state *, state ) ;
tomwalters@0:     BankSegment      **bankSeg, *segmentPointer, **GenerateBankSegments() ;
tomwalters@0:     double           density, freq, scale_disp, scale_vel ;
tomwalters@0:     double           qfactor, bn, xn, delta_xn, an, Lt, zov ;
tomwalters@0:     double           length, diam, attn ;
tomwalters@0:     Source           outputSource ;
tomwalters@0:     int              chan, total_chans, segment, counter = 0 ;
tomwalters@0: 
tomwalters@0:    /***** initialise input-related parameters *****/
tomwalters@0:      state->inout_size = sizeof ( DataType ) ;
tomwalters@0:      state->input  = ( char * ) 0 ;
tomwalters@0:      state->source = source ;
tomwalters@0: 
tomwalters@0:    /***** set WDF-TLF filterbank parameters *****/
tomwalters@0:      density = DensityOnScale( ErbScale( center_frequencies[ 0 ]), ErbScale( center_frequencies[ *chans - 1]),
tomwalters@0: 			       *chans ) ;
tomwalters@0:      if( density == 0. ) {
tomwalters@0: 	if( outdens <= 0. )
tomwalters@0: 	   density = 1. ;   /* arbitrary */
tomwalters@0: 	else
tomwalters@0: 	   density = outdens ;
tomwalters@0:      }
tomwalters@0: 
tomwalters@0:      if( interps > 0 )
tomwalters@0: 	interps = MIN( interps, ( int ) floor( log( ( double ) *chans ) / log( 2. ) ) ) ;
tomwalters@0: 
tomwalters@0:      bankSeg = GenerateBankSegments( interps, samplerate, center_frequencies, &density, &outdens, 
tomwalters@0: 				     chans, &total_chans ) ;
tomwalters@0:      state->display_chans = *chans ;
tomwalters@0:      state->total_chans  = total_chans ;
tomwalters@0:      state->states = NewArray( WDFilterState *, state->total_chans, "bank_tl.c for states" ) ;
tomwalters@0: 
tomwalters@0:      if( info )
tomwalters@0:         fprintf( stderr, "\nTLF filterbank information:\n" ) ; 
tomwalters@0: 
tomwalters@0:      xn = bankSeg[0]->position ;    
tomwalters@0:      delta_xn = bankSeg[0]->seglength ;    
tomwalters@0:      Lt = -2. * RHO_fluid / ( A0 * A_exp ) * ( exp( -A_exp * L ) - exp( -A_exp * ( xn + delta_xn ) ) ) ;
tomwalters@0: 
tomwalters@0:      for( chan = 0 ; chan < state->total_chans  ; chan++ ) {
tomwalters@0: 	  segmentPointer = bankSeg[ chan ] ;
tomwalters@0: 	  freq = segmentPointer->center_frequency ;
tomwalters@0: 	  xn = segmentPointer->position ;       
tomwalters@0: 	  delta_xn = MAX( segmentPointer->seglength, MinLength ) ;
tomwalters@0: 
tomwalters@0: 	/*** channel-dependent scalea cross-sectional area ***/
tomwalters@0: 	  an = A0 * exp( A_exp * xn ) ;        
tomwalters@0: 
tomwalters@0: 	/*** channel-dependent BM width ***/
tomwalters@0: 	  bn = B0 * exp( B_exp * xn ) ;
tomwalters@0: 
tomwalters@0: 	/*** channel-dependent Q-factor ***/
tomwalters@0: 	  if ( Q_CHANNEL != 0 )          
tomwalters@0: 	       qfactor = qbase * ( freq / REF_CF ) * ( Erb( REF_CF ) / Erb(freq) ) ;
tomwalters@0: 	  else
tomwalters@0: 	       qfactor = qbase ;
tomwalters@0: 
tomwalters@0: 	 /*** print filterbank configuration ***/
tomwalters@0:           if( info ) {
tomwalters@0:             counter += 1 * segmentPointer->active ;
tomwalters@0: 	    fprintf( stderr, "%3d -- active=%3d -- cf:%7.1f Hz =%6.2f ERBs -- x=%.3fcm  delta=%.3fcm  b=%.3fcm  A=%.3fcm2\n",
tomwalters@0: 		   state->total_chans - chan, counter * segmentPointer->active, freq, ErbScale( freq ), xn, delta_xn, bn, an ) ; 
tomwalters@0: 	  }
tomwalters@0: 
tomwalters@0: 	/*** scale output ***/
tomwalters@0: 	 scale_vel  = output_gain * FILTERBANK_SCALE ;
tomwalters@0: 	 scale_disp = TwoPi * REF_CF * scale_vel ;
tomwalters@0: 
tomwalters@0: 	/*** get filter states ***/
tomwalters@0: 	 state->states[ chan ] = WDFilter( samplerate, freq, scale_vel, scale_disp, RHO_fluid, an, bn, 
tomwalters@0: 					   qfactor, MASS_PER_AREA, delta_xn, Lt, WARPING, 
tomwalters@0: 					   segmentPointer->active, &zov, OHC_gain, OHC_sat ) ;
tomwalters@0: 
tomwalters@0: 	 Delete( segmentPointer ) ;
tomwalters@0:      }
tomwalters@0:    
tomwalters@0:      Delete( bankSeg ) ;
tomwalters@0: 
tomwalters@0:  
tomwalters@0:      /*** set parameters common to all channels ***/
tomwalters@0: 
tomwalters@0:      state->bank = New( TLF_BankInfo * ) ;
tomwalters@0:      state->bank->output_chans = state->display_chans ;
tomwalters@0: 
tomwalters@0:      /* set decimation parameters */
tomwalters@0:      state->bank->decimateCount = 0 ;
tomwalters@0:      *decimate_factor = MAX( 1, *decimate_factor ) ;
tomwalters@0:      state->bank->decimate_factor = *decimate_factor ;    
tomwalters@0:     
tomwalters@0: 
tomwalters@0:      /***** set output and nonlinearity variables, and filter procedure *****/
tomwalters@0: 
tomwalters@0:      if( strncmp( motionstr, "velocity", 3 ) == 0 ) {
tomwalters@0: 	state->proc = DoWDFdataArray ;
tomwalters@0: 	state->bank->output_var = VELOCITY ;
tomwalters@0: 	state->bank->nl_var = DISPLACEMENT ;
tomwalters@0:      }
tomwalters@0:      else {
tomwalters@0: 	state->proc = DoWDFdataArray ;
tomwalters@0: 	state->bank->output_var = DISPLACEMENT ;
tomwalters@0: 	state->bank->nl_var = DISPLACEMENT ;
tomwalters@0:      } 
tomwalters@0: 
tomwalters@0: 
tomwalters@0:    /***** Set WDF-EAR filter design parameters *****/
tomwalters@0:     state->wave_states = FreefieldWDF( samplerate, RHO_air, C, As, concha->diameter/2. ) ;
tomwalters@0: 
tomwalters@0:     state->Ntube = concha->Nsegments + canal->Nsegments ;
tomwalters@0:     state->eartube_states = NewArray( EartubeWDFstate *, state->Ntube, "ear.c for eartube states" ) ;
tomwalters@0: 
tomwalters@0:     length = concha->length / concha->Nsegments ;
tomwalters@0:     diam   = concha->diameter ;
tomwalters@0:     attn   = concha->att_factor ;
tomwalters@0:     for( segment = 0 ; segment < concha->Nsegments ; segment++ ) 
tomwalters@0: 	state->eartube_states[ segment ] = EartubeWDF( samplerate, RHO_air, C, diam, length, attn ) ;
tomwalters@0: 
tomwalters@0:     length = canal->length / canal->Nsegments ;
tomwalters@0:     diam   = canal->diameter ;
tomwalters@0:     attn   = canal->att_factor ;
tomwalters@0:     for( ; segment < state->Ntube ; segment++ ) 
tomwalters@0: 	state->eartube_states[ segment ] = EartubeWDF( samplerate, RHO_air, C, diam, length, attn ) ;
tomwalters@0: 
tomwalters@0:     state->earmiddle_states = EarmiddleWDF( samplerate, zov, 1.0, RATIO ) ;
tomwalters@0: 
tomwalters@0: 
tomwalters@0:    /***** specify procedures upon closing *****/
tomwalters@0:     state->closeEar = CloseEarWDF ;
tomwalters@0:     state->closeTLF = CloseWDF ;
tomwalters@0: 
tomwalters@0:    /***** initialise output-related parameters and return *****/
tomwalters@0:     outputSource = SetFillableSource( state, tlf_bank_callback, "bank_tl.c filter" ) ;
tomwalters@0: 
tomwalters@0:     for( *chans = state->display_chans ; interps-- > 0 ; *chans = *chans * 2 - 1, density = density * 2. )
tomwalters@0: 	outputSource = InterpSource( outputSource, *chans ) ;
tomwalters@0: 
tomwalters@0:     return ( outputSource ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: 
tomwalters@0: /************************** lower level functions *************************/
tomwalters@0: 
tomwalters@0: BankSegment **GenerateBankSegments( interps, samplerate, display_frequencies, display_dens, 
tomwalters@0: 				    out_dens, display_chans, total_chans )
tomwalters@0: int    interps ;
tomwalters@0: double samplerate ;
tomwalters@0: double *display_frequencies ;
tomwalters@0: double *display_dens, *out_dens ;
tomwalters@0: int    *display_chans, *total_chans ;
tomwalters@0: {
tomwalters@0:     BankSegment **bankSeg, *segmentPointer ;
tomwalters@0:     double      min_cf, max_cf ;
tomwalters@0:     double      apical_cf, basal_cf ;
tomwalters@0:     double      *apical_frequencies, *basal_frequencies ;
tomwalters@0:     double      apical_dens, basal_dens, central_dens ;
tomwalters@0:     int         apical_chans, basal_chans, central_chans ;
tomwalters@0:     int         ichan, chan ;
tomwalters@0:     int         remainder ; 
tomwalters@0:     double      cm_per_CB = GetERBscaling ( ) / 10. ;
tomwalters@0: 
tomwalters@0: 
tomwalters@0:    /***** set number and density of central channels *****/
tomwalters@0:     if( interps >= 0 ) {
tomwalters@0: 
tomwalters@0: 	central_chans = *display_chans = *display_chans >> interps ;
tomwalters@0: 	central_dens  = *display_dens  = ldexp( *display_dens, -interps ) ;
tomwalters@0: 	min_cf        = FofErbScale( ErbScale( display_frequencies[0] ) - 1. / central_dens ) ;      
tomwalters@0: 	max_cf        = display_frequencies[ ( central_chans - 1 ) << interps ] ;
tomwalters@0:     }
tomwalters@0: 
tomwalters@0:     else {
tomwalters@0: 	central_chans = *display_chans << -interps ;
tomwalters@0: 	central_dens  = ldexp( *display_dens, -interps ) ;
tomwalters@0: 	min_cf        = FofErbScale( ErbScale( display_frequencies[0] ) 
tomwalters@0: 				     - ( 1 << -interps ) / central_dens ) ;
tomwalters@0: 	max_cf        = display_frequencies[*display_chans - 1] ; 
tomwalters@0:     }
tomwalters@0: 
tomwalters@0: 
tomwalters@0:    /***** set number and density of apical and basal channels outside display range *****/ 
tomwalters@0: 
tomwalters@0:     if( *out_dens <= 0. ) {
tomwalters@0: 
tomwalters@0: 	apical_cf = min_cf ;
tomwalters@0: 	apical_dens  = 0. ;
tomwalters@0: 	basal_cf = max_cf ;
tomwalters@0: 	basal_dens = 0. ;
tomwalters@0:     }
tomwalters@0:     else {
tomwalters@0: 	apical_cf = adjustCF( MIN_CF, samplerate ) ;
tomwalters@0: 	apical_dens = *out_dens ;
tomwalters@0: 	basal_cf  = adjustCF( MAX_CF, samplerate ) ;
tomwalters@0: 	basal_dens = *out_dens ;
tomwalters@0:     }
tomwalters@0: 
tomwalters@0: 	apical_chans = 0 ;
tomwalters@0: 	basal_chans = 0 ;
tomwalters@0:     
tomwalters@0: 
tomwalters@0:    /***** generate apical and basal center frequencies outside display range *****/ 
tomwalters@0: 
tomwalters@0:     apical_frequencies = GenerateFrequencies( apical_cf, min_cf, min_cf, &apical_dens, &apical_chans ) ;
tomwalters@0:     basal_frequencies = GenerateFrequencies( max_cf, basal_cf, max_cf, &basal_dens, &basal_chans ) ;
tomwalters@0: 
tomwalters@0:    /***** fill in array of BanKSegment structures with BM segment info *****/
tomwalters@0:     *total_chans = apical_chans + central_chans + basal_chans - 2 ;   
tomwalters@0:     bankSeg = NewArray( BankSegment *, *total_chans + 1, "tl_bank.c for segments" ) ;
tomwalters@0: 
tomwalters@0:     ichan = 0 ;
tomwalters@0:     for( chan = 1 ; chan < apical_chans ; chan++ ) {
tomwalters@0: 
tomwalters@0: 	 bankSeg[ ichan++ ] = segmentPointer = New( BankSegment * ) ; 
tomwalters@0: 	 segmentPointer->center_frequency = apical_frequencies[ chan ] ;
tomwalters@0: 	 segmentPointer->seglength = cm_per_CB / apical_dens ;  
tomwalters@0: 	 segmentPointer->position = L - cm_per_CB * ErbScale( segmentPointer->center_frequency ) ; 
tomwalters@0: 	 segmentPointer->active = 0 ;
tomwalters@0:     }
tomwalters@0: 
tomwalters@0:     for( chan = 0 ; chan < central_chans ; chan++ ) {
tomwalters@0: 
tomwalters@0: 	 bankSeg[ ichan++ ] = segmentPointer = New( BankSegment * ) ;         
tomwalters@0: 
tomwalters@0: 	 if( interps >= 0 ) {
tomwalters@0: 	     segmentPointer->center_frequency = display_frequencies[ chan << interps ] ;
tomwalters@0: 	     segmentPointer->active = 1 ;
tomwalters@0: 	 }
tomwalters@0: 	 else {
tomwalters@0: 	     remainder =  chan % ( 1 << -interps ) ;
tomwalters@0: 	     segmentPointer->center_frequency = FofErbScale( ErbScale( display_frequencies[ chan >> -interps ] )
tomwalters@0: 						+ ( remainder - ( 1 << -interps ) + 1 ) / central_dens ) ;
tomwalters@0: 	     segmentPointer->active = ( remainder == ( ( 1 << -interps ) - 1 ) ) ;
tomwalters@0: 	 }
tomwalters@0: 
tomwalters@0: 	 segmentPointer->seglength = cm_per_CB / central_dens ;  
tomwalters@0: 	 segmentPointer->position = L - cm_per_CB * ErbScale( segmentPointer->center_frequency ) ; 
tomwalters@0:     }
tomwalters@0: 
tomwalters@0: 
tomwalters@0:     for( chan = 1 ; chan < basal_chans ;  chan++ ) {
tomwalters@0: 
tomwalters@0: 	 bankSeg[ ichan++ ] = segmentPointer = New( BankSegment * ) ;
tomwalters@0: 	 segmentPointer->center_frequency = basal_frequencies[ chan ] ;
tomwalters@0: 	 segmentPointer->seglength = cm_per_CB / basal_dens ;  
tomwalters@0: 	 segmentPointer->position = L - cm_per_CB * ErbScale( segmentPointer->center_frequency ) ; 
tomwalters@0: 	 segmentPointer->active = 0 ;
tomwalters@0:     }
tomwalters@0: 
tomwalters@0:     segmentPointer = bankSeg[ 0 ] ;
tomwalters@0:     if( ( segmentPointer->position + segmentPointer->seglength ) > L ) 
tomwalters@0: 	segmentPointer->seglength = L - MIN( L, segmentPointer->position ) ;
tomwalters@0: 
tomwalters@0:    /***** return and deallocate dynamic memory *****/
tomwalters@0:     Delete( apical_frequencies ) ;
tomwalters@0:     Delete(  basal_frequencies ) ;
tomwalters@0: 
tomwalters@0:     return( bankSeg ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: 
tomwalters@0: double *GenerateFrequencies( min_cf, max_cf, base_cf, density, channels )
tomwalters@0: double  min_cf, max_cf, base_cf ;
tomwalters@0: double  *density ;
tomwalters@0: int     *channels ;
tomwalters@0: {
tomwalters@0:     double freq, *frequencies ;
tomwalters@0: 
tomwalters@0:    /*** map characteristic frequencies onto specified scale ***/ 
tomwalters@0:     min_cf = ErbScale( min_cf ) ;
tomwalters@0:     max_cf = ErbScale( max_cf ) ;
tomwalters@0:     max_cf = MAX( min_cf, max_cf ) ;                 /* max_cf cannot be smaller than min_cf */ 
tomwalters@0:     base_cf = ErbScale( base_cf ) ;
tomwalters@0: 
tomwalters@0: 
tomwalters@0:    /*** call appropriate generating functions ***/
tomwalters@0:     if( *channels <= 0 ) {
tomwalters@0: 
tomwalters@0:        if( *density <= 0. ) {
tomwalters@0: 	  *channels = 1 ;                           /* there must be at least one channel */
tomwalters@0: 	  freq = FofErbScale( min_cf ) ;            /* arbitrary */
tomwalters@0: 	  frequencies = &freq ;
tomwalters@0: 	  *density = 1. ;                           /* arbitrary */
tomwalters@0: 
tomwalters@0:        }
tomwalters@0:        else {
tomwalters@0: 	  frequencies = GenerateScale( min_cf, max_cf, *density, base_cf, FofErbScale ) ;
tomwalters@0: 	  *channels   = NumberOnScale( min_cf, max_cf, *density, base_cf ) ;
tomwalters@0:        }
tomwalters@0:     }
tomwalters@0: 
tomwalters@0:     else {
tomwalters@0:        frequencies = NumberedScale( min_cf, max_cf, *channels, FofErbScale ) ;
tomwalters@0:        *density    = DensityOnScale( min_cf, max_cf, *channels ) ;
tomwalters@0:        if( *density == 0. )
tomwalters@0: 	  *density = 1. ;    /* arbitrary */
tomwalters@0:     }
tomwalters@0: 
tomwalters@0:    /*** return pointer to array of center frequencies ***/
tomwalters@0:     return ( frequencies ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: 
tomwalters@0: double adjustCF( cf, samplerate )
tomwalters@0: double cf, samplerate ;
tomwalters@0: {
tomwalters@0:     cf = MAX( cf, MIN_CF ) ;                      
tomwalters@0:     cf = MAX( cf, FofErbScale( 0. ) ) ;                    
tomwalters@0: 
tomwalters@0:     cf = MIN( cf, samplerate / 2. ) ;
tomwalters@0:     cf = MIN( cf, MAX_CF ) ;
tomwalters@0:     cf = MIN( cf, FofErbScale( 10. * L / GetERBscaling() ) );
tomwalters@0: 
tomwalters@0:     return ( cf ) ;
tomwalters@0: }
tomwalters@0: