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added RealToHalfComplexTransform

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Ahmet Inan 2019-04-25 15:14:19 +02:00
commit 4025bd126c
1 changed files with 35 additions and 0 deletions
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fft.hh
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@ -1125,5 +1125,40 @@ public:
}
};
template <int BINS, typename TYPE>
class RealToHalfComplexTransform
{
static_assert(BINS%2==0, "BINS must be even");
static const int N = BINS / 2;
TYPE factors[N];
TYPE A[N], B[N];
public:
typedef typename TYPE::value_type value_type;
RealToHalfComplexTransform()
{
for (int n = 0; n < N; ++n)
factors[n] = TYPE(UnitCircle<value_type>::cos(n, N), -UnitCircle<value_type>::sin(n, N));
for (int n = 0; n < N; ++n) {
TYPE sincos(
UnitCircle<value_type>::sin(n, BINS),
UnitCircle<value_type>::cos(n, BINS)
);
A[n] = value_type(0.5) * (TYPE(1) - sincos);
B[n] = value_type(0.5) * (TYPE(1) + sincos);
}
}
inline void operator ()(TYPE *out, const value_type *in)
{
FFT::Dit<FFT::split(N), N, 1, TYPE, -1>::dit(out, reinterpret_cast<const TYPE *>(in), factors);
out[N] = value_type(0.5) * (out[0].real() - out[0].imag());
out[0] = value_type(0.5) * (out[0].real() + out[0].imag());
for (int i = 1; i <= N/2; ++i) {
TYPE tmp = out[i]*A[i] + conj(out[N-i])*B[i];
out[N-i] = out[N-i]*A[N-i] + conj(out[i])*B[N-i];
out[i] = tmp;
}
}
};
}