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Further MatchedFilter optimization using algebraic identities and stuff.
Can't stop premature optimization!!!
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@ -31,27 +31,27 @@ bool MatchedFilter::execute_once(
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advance_decimation_phase();
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if( is_new_decimation_cycle() ) {
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float r_n = 0.0f;
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float i_n = 0.0f;
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float r_p = 0.0f;
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float i_p = 0.0f;
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float sr_tr = 0.0f;
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float si_tr = 0.0f;
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float si_ti = 0.0f;
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float sr_ti = 0.0f;
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for(size_t n=0; n<taps_count_; n++) {
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const auto sample = samples_[n];
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const auto tap = taps_reversed_[n];
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// N: complex multiple of samples and taps (conjugate, tap.i negated).
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// P: complex multiply of samples and taps.
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r_n += sample.real() * tap.real();
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i_n -= sample.real() * tap.imag();
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r_n += sample.imag() * tap.imag();
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i_n += sample.imag() * tap.real();
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r_p += sample.real() * tap.real();
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i_p += sample.real() * tap.imag();
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r_p -= sample.imag() * tap.imag();
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i_p += sample.imag() * tap.real();
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sr_tr += sample.real() * tap.real();
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si_ti += sample.imag() * tap.imag();
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si_tr += sample.imag() * tap.real();
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sr_ti += sample.real() * tap.imag();
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}
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// N: complex multiple of samples and taps (conjugate, tap.i negated).
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// P: complex multiply of samples and taps.
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const auto r_n = sr_tr + si_ti;
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const auto r_p = sr_tr - si_ti;
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const auto i_n = si_tr - sr_ti;
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const auto i_p = si_tr + sr_ti;
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const auto mag_n = std::sqrt(r_n * r_n + i_n * i_n);
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const auto mag_p = std::sqrt(r_p * r_p + i_p * i_p);
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const auto diff = mag_p - mag_n;
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