#ifndef INCLUDE_FOURIERTRANSFORM_H
#define INCLUDE_FOURIERTRANSFORM_H
/*
* This is the Loris C++ Class Library, implementing analysis,
* manipulation, and synthesis of digitized sounds using the Reassigned
* Bandwidth-Enhanced Additive Sound Model.
*
* Loris is Copyright (c) 1999-2010 by Kelly Fitz and Lippold Haken
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY, without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*
* FourierTransform.h
*
* Definition of class Loris::FourierTransform, providing a simplified
* uniform interface to the FFTW library (www.fftw.org), version 2.1.3
* or newer (including version 3), or to the General Purpose FFT package
* by Takuya OOURA, http://momonga.t.u-tokyo.ac.jp/~ooura/fft.html if
* FFTW is unavailable.
*
* Kelly Fitz, 2 Jun 2006
* loris@cerlsoundgroup.org
*
* http://www.cerlsoundgroup.org/Loris/
*
*/
#include <complex>
#include <vector>
// begin namespace
namespace Loris {
// insulating implementation class, defined in FourierTransform.C
class FTimpl;
// ---------------------------------------------------------------------------
// class FourierTransform
//
//! FourierTransform provides a simplified interface to the FFTW library
//! (www.fftw.org). Loris uses the FFTW library to perform efficient
//! Fourier transforms of arbitrary length. Clients store and access
//! the in-place transform data as a sequence of std::complex< double >.
//! Samples are stored in the FourierTransform instance using subscript
//! or iterator access, the transform is computed by the transform member,
//! and the transformed samples replace the input samples, and are
//! accessed by subscript or iterator. FourierTransform computes a complex
//! transform, so it can be used to invert a transform of real samples
//! as well. Uses the standard library complex class, which implements
//! arithmetic operations.
//!
//! Supports FFTW versions 2 and 3.
//! Does not make use of FFTW "wisdom" to speed up transform computation.
//!
//! If FFTW is unavailable, uses instead the General Purpose FFT package
//! by Takuya OOURA, http://momonga.t.u-tokyo.ac.jp/~ooura/fft.html defined
//! in fftsg.c for power-of-two transforms, and a very slow direct DFT
//! implementation for non-PO2 transforms.
//
class FourierTransform
{
// -- public interface --
public:
//! An unsigned integral type large enough
//! to represent the length of any transform.
typedef std::vector< std::complex< double > >::size_type size_type;
//! The type of a non-const iterator of (complex) transform samples.
typedef std::vector< std::complex< double > >::iterator iterator;
//! The type of a const iterator of (complex) transform samples.
typedef std::vector< std::complex< double > >::const_iterator const_iterator;
// --- lifecycle ---
//! Initialize a new FourierTransform of the specified size.
//!
//! \param len is the length of the transform in samples (the
//! number of samples in the transform)
//! \throw RuntimeError if the necessary buffers cannot be
//! allocated, or there is an error configuring FFTW.
FourierTransform( size_type len );
//! Initialize a new FourierTransform that is a copy of another,
//! having the same size and the same buffer contents.
//!
//! \param rhs is the instance to copy
//! \throw RuntimeError if the necessary buffers cannot be
//! allocated, or there is an error configuring FFTW.
FourierTransform( const FourierTransform & rhs );
//! Free the resources associated with this FourierTransform.
~FourierTransform( void );
// --- operators ---
//! Make this FourierTransform a copy of another, having
//! the same size and buffer contents.
//!
//! \param rhs is the instance to copy
//! \return a refernce to this instance
//! \throw RuntimeError if the necessary buffers cannot be
//! allocated, or there is an error configuring FFTW.
FourierTransform & operator= ( const FourierTransform & rhs );
// --- access/mutation ---
//! Access (read/write) a transform sample by index.
//! Use this member to fill the transform buffer before
//! computing the transform, and to access the samples
//! after computing the transform. (inlined for speed)
//!
//! \param index is the index or rank of the complex
//! transform sample to access. Zero is the first
//! position in the buffer.
//! \return non-const reference to the std::complex< double >
//! at the specified position in the buffer.
std::complex< double > & operator[] ( size_type index )
{
return _buffer[ index ];
}
//! Access (read-only) a transform sample by index.
//! Use this member to fill the transform buffer before
//! computing the transform, and to access the samples
//! after computing the transform. (inlined for speed)
//!
//! \param index is the index or rank of the complex
//! transform sample to access. Zero is the first
//! position in the buffer.
//! \return const reference to the std::complex< double >
//! at the specified position in the buffer.
const std::complex< double > & operator[] ( size_type index ) const
{
return _buffer[ index ];
}
//! Return an iterator refering to the beginning of the sequence of
//! complex samples in the transform buffer.
//!
//! \return a non-const iterator refering to the first position
//! in the transform buffer.
iterator begin( void )
{
return _buffer.begin();
}
//! Return an iterator refering to the end of the sequence of
//! complex samples in the transform buffer.
//!
//! \return a non-const iterator refering to one past the last
//! position in the transform buffer.
iterator end( void )
{
return _buffer.end();
}
//! Return a const iterator refering to the beginning of the sequence of
//! complex samples in the transform buffer.
//!
//! \return a const iterator refering to the first position
//! in the transform buffer.
const_iterator begin( void ) const
{
return _buffer.begin();
}
//! Return a const iterator refering to the end of the sequence of
//! complex samples in the transform buffer.
//!
//! \return a const iterator refering to one past the last
//! position in the transform buffer.
const_iterator end( void ) const
{
return _buffer.end();
}
// --- operations ---
//! Compute the Fourier transform of the samples stored in the
//! transform buffer. The samples stored in the transform buffer
//! (accessed by index or by iterator) are replaced by the
//! transformed samples, in-place.
void transform( void );
// --- inquiry ---
//! Return the length of the transform (in samples).
//!
//! \return the length of the transform in samples.
size_type size( void ) const ;
// -- instance variables --
private:
//! buffer containing the complex transform input before
//! computing the transform, and the complex transform output
//! after computing the transform
std::vector< std::complex< double > > _buffer;
// insulating implementation instance (defined in
// FourierTransform.C), conceals interface to FFTW
FTimpl * _impl;
}; // end of class FourierTransform
} // end of namespace Loris
#endif /* ndef INCLUDE_FOURIERTRANSFORM_H */