extern int input_dsp();
extern void output_dsp();
extern int abs();
extern float fabs();
extern float fmod();
extern float asin();
extern float acos();
extern float ceil();
extern float cos();
extern float exp();
extern float floor();
extern float log();
extern float log10();
extern float sin();
extern float sqrt();
extern float pow();
extern float tan();
extern float atan();

float data_real[1024];
float data_imag[1024];
float coef_real[1024];
float coef_imag[1024];

void fft(float data_real[],float data_imag[], float coef_real[],
                 float coef_imag[]);

main()
{
  int i;

  input_dsp (data_real, 1024, 0);

  for (i=0 ; i<1024 ; i++){
    data_imag[i] = 1;
    coef_real[i] = 1;
    coef_imag[i] = 1;
  }
  fft(data_real, data_imag, coef_real, coef_imag);

  output_dsp (data_real, 1024, 0);
  output_dsp (data_imag, 1024, 0);
  output_dsp (coef_real, 1024, 0);
  output_dsp (coef_imag, 1024, 0);

}

void fft(float data_real[],float data_imag[], float coef_real[],
                 float coef_imag[])




{
  int i;
  int j;
  int k;

  float temp_real;
  float temp_imag;
  float Wr;
  float Wi;

  int groupsPerStage = 1;
  int buttersPerGroup = 1024 / 2;
  for (i = 0; i < 10; ++i) {
    for (j = 0; j < groupsPerStage; ++j) {
      Wr = coef_real[(1<<i)-1+j];
      Wi = coef_imag[(1<<i)-1+j];
      for (k = 0; k < buttersPerGroup; ++k) {
        temp_real = Wr * data_real[2*j*buttersPerGroup+buttersPerGroup+k] -
                    Wi * data_imag[2*j*buttersPerGroup+buttersPerGroup+k];
        temp_imag = Wi * data_real[2*j*buttersPerGroup+buttersPerGroup+k] +
                    Wr * data_imag[2*j*buttersPerGroup+buttersPerGroup+k];
        data_real[2*j*buttersPerGroup+buttersPerGroup+k] =
                    data_real[2*j*buttersPerGroup+k] - temp_real;
        data_real[2*j*buttersPerGroup+k] += temp_real;
        data_imag[2*j*buttersPerGroup+buttersPerGroup+k] =
                    data_imag[2*j*buttersPerGroup+k] - temp_imag;
        data_imag[2*j*buttersPerGroup+k] += temp_imag;
      }
    }
    groupsPerStage <<= 1;
    buttersPerGroup >>= 1;
  }
}