echomap::FFTWBuffers Class Reference

Simple RAII wrapper for commonly used C types from FFTW(f). More...

#include <FFTWBuffers.hpp>

Public Member Functions
	FFTWBuffers (std::size_t size, const std::optional< std::span< const float > > &inplace_input)
	Setup contextual buffers for FFTW.
	~FFTWBuffers () noexcept
	Deallocate the buffers.

Public Attributes
fftwf_complex_fwd *const	coefficients
	Complex coefficients (output of real-to-complex FFT).
float *	input
	Real-valued inputs, either managed by us or aliased by the user.
std::size_t	input_size
	Size of the input vector.

Private Types
using	fftwf_complex_fwd = float[2]

Private Attributes
bool	is_input_managed
	Are we responsible for the input buffer?

Detailed Description

Simple RAII wrapper for commonly used C types from FFTW(f).

This interface is intentionally "raw" (e.g. direct access to member variables) since it's often used in hot loops. We want to make it as easy as possible for the optimiser.

Definition at line 26 of file FFTWBuffers.hpp.

Member Typedef Documentation

fftwf_complex_fwd

using echomap::FFTWBuffers::fftwf_complex_fwd = float[2]

private

Definition at line 28 of file FFTWBuffers.hpp.

Constructor & Destructor Documentation

FFTWBuffers()

echomap::FFTWBuffers::FFTWBuffers ( std::size_t size, const std::optional< std::span< const float > > & inplace_input )

explicit

Setup contextual buffers for FFTW.

Parameters

size	The number of samples in the input data.
inplace_input	The array to which the input should be aliased; if not provided, FFTW allocates a real-valued array in the size of the given sample count.

Exceptions

std::runtime_error

One or more buffers could not be allocated.

Postcondition

The coefficients buffer is non-null.

The input buffer is non-null.

Definition at line 21 of file FFTWBuffers.cpp.

  :
    coefficients(fftwf_alloc_complex(size / 2 + 1)),
    input(inplace_input.has_value() ? const_cast<float*>(inplace_input->data()) : fftwf_alloc_real(size)),
    input_size(size),
    is_input_managed(!inplace_input.has_value())
{
    /*
     * It's not very nice, but we cast away the const on the input buffer as required by the FFTW C API. We know that
     * in-place transforms are not going to take place, so it doesn't make sense to take optional<float*> (mutable
     * pointer) as a constructor parameter.
     */
 
    if (coefficients == nullptr)
        throw std::runtime_error("Failed to create FFTW coefficients buffer.");
 
    if (!inplace_input.has_value() && input == nullptr) {
        fftwf_free(coefficients);
        throw std::runtime_error("Failed to create FFTW input buffer.");
    }
 
    assert(input != nullptr);
    assert(coefficients != nullptr);
}

~FFTWBuffers()

echomap::FFTWBuffers::~FFTWBuffers ( )

noexcept

Deallocate the buffers.

Definition at line 48 of file FFTWBuffers.cpp.

{
    if (is_input_managed && input != nullptr)
        fftwf_free(input);
 
    if (coefficients != nullptr)
        fftwf_free(coefficients);
}

Member Data Documentation

coefficients

fftwf_complex_fwd* const echomap::FFTWBuffers::coefficients

Complex coefficients (output of real-to-complex FFT).

Definition at line 31 of file FFTWBuffers.hpp.

input

float* echomap::FFTWBuffers::input

Real-valued inputs, either managed by us or aliased by the user.

Definition at line 32 of file FFTWBuffers.hpp.

input_size

std::size_t echomap::FFTWBuffers::input_size

Size of the input vector.

Definition at line 33 of file FFTWBuffers.hpp.

is_input_managed

bool echomap::FFTWBuffers::is_input_managed

private

Are we responsible for the input buffer?

Definition at line 58 of file FFTWBuffers.hpp.

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The documentation for this class was generated from the following files:

• src/objects/factories/FFTWBuffers.hpp
• src/objects/factories/FFTWBuffers.cpp