void AccelerateFFT<double>::performFFT (double* buffer, double* real, double* imag)
{
vDSP_ctozD ((DOUBLE_COMPLEX*)buffer, 2, &doubleComplexSplit, 1, fftSizeOver2);
vDSP_fft_zripD (fftSetupDouble, &doubleComplexSplit, 1, log2n, FFT_FORWARD);
doubleComplexSplit.realp[fftSizeOver2] = doubleComplexSplit.imagp[0];
doubleComplexSplit.imagp[fftSizeOver2] = 0.0;
doubleComplexSplit.imagp[0] = 0.0;
for (size_t i = 0; i <= fftSizeOver2; i++)
{
doubleComplexSplit.realp[i] *= 0.5;
doubleComplexSplit.imagp[i] *= 0.5;
}
for (size_t i = fftSizeOver2 - 1; i > 0; --i)
{
doubleComplexSplit.realp[2 * fftSizeOver2 - i] = doubleComplexSplit.realp[i];
doubleComplexSplit.imagp[2 * fftSizeOver2 - i] = -1 * doubleComplexSplit.imagp[i];
}
for (size_t i = 0; i < fftSize; i++)
{
real[i] = doubleComplexSplit.realp[i];
imag[i] = doubleComplexSplit.imagp[i];
}
}
void
FFTLib_op::ComputeFrame(int N, double *in, double *out)
{
vDSP_ctozD ((DSPDoubleComplex*) in, 2, &A, 1, N/2 );
vDSP_fft_zripD(SetupReal, &A, 1, Exp, FFT_FORWARD);
int i,j;
for (i=0; i<N/2; i++)
out[i] = A.realp[i]*0.5;
out[N/2] = A.imagp[0]*0.5;
for (i=1, j=N-1; i<N/2; i++, j--)
out[j] = A.imagp[i]*0.5;
}
int xtract_autocorrelation_fft(const double *data, const int N, const void *argv, double *result)
{
double *rfft = NULL;
int n = 0;
int M = 0;
#ifndef USE_OOURA
DSPDoubleSplitComplex *fft = NULL;
double M_double = 0.0;
#endif
M = N << 1;
/* Zero pad the input vector */
rfft = (double *)calloc(M, sizeof(double));
memcpy(rfft, data, N * sizeof(double));
#ifdef USE_OOURA
rdft(M, 1, rfft, ooura_data_autocorrelation_fft.ooura_ip,
ooura_data_autocorrelation_fft.ooura_w);
for(n = 2; n < M; ++n)
{
rfft[n*2] = XTRACT_SQ(rfft[n*2]) + XTRACT_SQ(rfft[n*2+1]);
rfft[n*2+1] = 0.0;
}
rfft[0] = XTRACT_SQ(rfft[0]);
rfft[1] = XTRACT_SQ(rfft[1]);
rdft(M, -1, rfft, ooura_data_autocorrelation_fft.ooura_ip,
ooura_data_autocorrelation_fft.ooura_w);
#else
/* vDSP has its own autocorrelation function, but it doesn't fit the
* LibXtract model, e.g. we can't guarantee it's going to use
* an FFT for all values of N */
fft = &vdsp_data_autocorrelation_fft.fft;
vDSP_ctozD((DSPDoubleComplex *)data, 2, fft, 1, N);
vDSP_fft_zripD(vdsp_data_autocorrelation_fft.setup, fft, 1,
vdsp_data_autocorrelation_fft.log2N, FFT_FORWARD);
for(n = 0; n < N; ++n)
{
fft->realp[n] = XTRACT_SQ(fft->realp[n]) + XTRACT_SQ(fft->imagp[n]);
fft->imagp[n] = 0.0;
}
vDSP_fft_zripD(vdsp_data_autocorrelation_fft.setup, fft, 1,
vdsp_data_autocorrelation_fft.log2N, FFT_INVERSE);
#endif
/* Normalisation factor */
M = M * N;
#ifdef USE_OOURA
for(n = 0; n < N; n++)
result[n] = rfft[n] / (double)M;
free(rfft);
#else
M_double = (double)M;
vDSP_ztocD(fft, 1, (DOUBLE_COMPLEX *)result, 2, N);
vDSP_vsdivD(result, 1, &M_double, result, 1, N);
#endif
return XTRACT_SUCCESS;
}