FFTW lib bindings for Odin

These are bindings for the FFTW - Fast Fourier Transform in the West, for the Odin programming language.

Description

These are bindings to the FFTW library - The Fastest Fourier Transform in the West, so you can do the FFT and Inverse FFT on f32 buffers. FFTW also allows for calculation of FFT's on f64, but I didn't mapped it, it has to be linked with a different version of the library, that also comes with the Linux version that one installs with the package manager of your distribution. The FFTW library is a C library, so this binding is a C binding. The FFTW library is a very fast FFT, also popular library and it is very easy to use. These bindings also use GCC to compile the .o obj file.

Installation

To install the FFTW on your Linux use the FFTW package from your distribution.

Example of usage

See the file fftw_main.odin for a full example of usage.

import f "./fftw"

main :: proc () {

    // Allocates the memory for the in and out arrays for the fftw plan.
    buf_in  : [^]f.fftwf_complex
    buf_out : [^]f.fftwf_complex
    n_samples   : int = 10
    sample_rate : int = 10  // Samples per second.
    buf_in  = f.od_fftwf_malloc( n_samples )
    buf_out = f.od_fftwf_malloc( n_samples )


    // Creates the fftw plan for "in" and "out" buffer.
    plan : f.fftwf_plan
    plan = f.od_fftwf_plan_dft_1d( n_samples,
                                   buf_in,
                                   buf_out,
                                   int( f.Sign.FFTW_Forward ),
                                   uint( f.Flags.FFTW_Estimate ) )


    // 1º FFT

    // Fill in_a[] with data with size n_samples, at sample_rate, at sin_freq 
    // with a  sin ( 2 * pi * f * t ) where t = i / sample_rate
    
    sin_freq : f32 = 2    // Hz
    fill_array_with_sin( buf_in, n_samples, sample_rate, sin_freq )

    // Print in[].
    print_complex_array( "in A", buf_in, n_samples, false )
 
    // Execute the fftw plan.
    f.od_fftwf_execute( plan )

    // Print out[].
    print_complex_array( "out A", buf_out, n_samples, true )
 
    f.correct_complex_array_scale( buf_out, n_samples )

    // Print out[].
    print_complex_array( "out A scale factor corrected", buf_out, n_samples, true )
 

    // Destroy the fftw plan.
    f.od_fftwf_destroy_plan( plan )

    // Frees the memory for the "in" and "out" arrays for the fftw plan.
    f.od_fftwf_free( buf_out )
    f.od_fftwf_free( buf_in )

}

License

My code is MIT Open Source license, but the FFTW library has it's own license. So usage of this library, must be in accordance with the FFTW license.

Have fun

Best regards,
João Carvalho