test_fft.c

This a framework to test new ideas in transmission technology. Actual development is a LDPC-coder in

/***************************************************************************
              test_fft.c  -  Module for testing the fft-routines
                            -------------------
    begin                :  2004
    authors              :  Linus Gasser
    emails               :  [e-mail]
 ***************************************************************************/

/***************************************************************************
                                 Changes
                                 -------
 date - name - description
 04/01/28 - ineiti - begin
 
 **************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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.                                   *
 *                                                                         *
 ***************************************************************************/


char desc[] =
"Description:\n"
"Tests the internal (non-optimized) fft-functions. The signal\n"
"is composed of two peaks (the fft of a sin), and is then\n"
"fft'ed, which should give a sine, and then ifft'ed, which\n"
"should give again the original signal.\n\n";

#include <complex.h>
#include <math.h>
#include "spc.h"
#include "std.h"

#define DBG_LVL 4


void print_complex( char *str, complex double *v, int len ){
  int i;
  
  PR( str );
  for ( i=0; i<len; i++ ){
    double re = ((int)( creal( v[i] ) * 10 )) / 10.;
    double im = ((int)( cimag( v[i] ) * 10 )) / 10.;
    PR_CL( "\n%-4g + %gi", re, im );
  }
  PR_CL( "\n" );
}

#define FFT_LEN 8
void *start_it( void *arg ) {
  complex double x[FFT_LEN] = { 0, 1, 0, 0,  0, 0, 1, 0 };

  print_complex( "This signal ", x, FFT_LEN );
  swr_fft_complex( x, logb( FFT_LEN ), SWR_FFT );
  print_complex( "Has this FFT ", x, FFT_LEN );
  swr_fft_complex( x, logb( FFT_LEN ), SWR_IFFT );
  print_complex( "And should be identical with ", x, FFT_LEN );
  
  return 0;
}

swr_spc_id_t spm_id;

struct thread start;
/**
 * This function is called upon "insmod" and is used to register the
 * different parts of the module to the SPM.
 */
int um_module_init(void) {

  PR_CL( desc );
  if ( swr_thread_init( &start, start_it, NULL ) < 0 )
    goto first_no_stack;
  return 0;

first_no_stack:
  PR_DBG( 0, "Couldn't allocate stack\n" );
  return -1;
}

void um_module_exit( void ) {

  swr_thread_free( &start, NULL );

}


module_init( um_module_init );
module_exit( um_module_exit );