OSFilter.hxx

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/*
  Copyright (c) 2012, Matthew H. Reilly (kb1vc)
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are
  met:

  Redistributions of source code must retain the above copyright
  notice, this list of conditions and the following disclaimer.
  Redistributions in binary form must reproduce the above copyright
  notice, this list of conditions and the following disclaimer in
  the documentation and/or other materials provided with the
  distribution.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef OS_FILTER_HDR
#define OS_FILTER_HDR



#include <fstream>
#include <complex>
#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fftw3.h>
namespace SoDa {
  class OSFilter {
  public:
    

#if 0    
    OSFilter(float * filter_impulse_response,
         unsigned int filter_length,
         float filter_gain, 
         unsigned int inout_buffer_length,
         OSFilter * cascade = NULL,
         unsigned int suggested_transform_length = 0);
#endif
    
    OSFilter(float low_cutoff,
         float low_pass_edge,
         float high_pass_edge,
         float high_cutoff,

         unsigned int filter_length,
         float filter_gain, 
         float sample_rate, 

         unsigned int inout_buffer_length,
         unsigned int suggested_transform_length = 0);
    
    unsigned int apply(std::complex<float> * inbuf, std::complex<float> * outbuf, float outgain = 1.0);

    unsigned int apply(float * inbuf, float * outbuf, float outgain = 1.0,
               int instride = 1, int outstride = 1);

    void dump(std::ostream & os);

    std::pair<double, double> getFilterEdges() { 
      return std::pair<double, double>(low_edge, high_edge); 
    }

  protected:
    double low_edge, high_edge; 

    int guessN();
    void setupFFT();

    
    
    // these are the salient dimensions for this Overlap/Save
    // widget (for terminology, see Lyons pages 719ff
    unsigned int M; 
    unsigned int Q; 
    unsigned int N; 

    // some helpful stuff.
    unsigned int tail_index; 
    
    // these are the intermediate buffers
    std::complex<float> * fft_input;  
    std::complex<float> * fft_output; 
    std::complex<float> * ifft_output; 

    // this is the FFT image of the filter
    std::complex<float> * filter_fft;  
    
    // each filter needs two plans, a forward and backward
    // plan for the FFT and IFFT
    fftwf_plan forward_plan, backward_plan; 
  };
}

#endif