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Cache IIR filter state because compiler *sometimes* doesn't want to.

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This commit is contained in:
Jared Boone 2016-01-11 15:44:42 -08:00
parent e169a46367
commit 5e917ebb2c
2 changed files with 19 additions and 16 deletions
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33
firmware/baseband/dsp_iir.cpp
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@ -28,27 +28,32 @@ void IIRBiquadFilter::configure(const iir_biquad_config_t& new_config) {
}
void IIRBiquadFilter::execute(const buffer_s16_t& buffer_in, const buffer_s16_t& buffer_out) {
const auto a_ = config.a;
const auto b_ = config.b;
auto x_ = x;
auto y_ = y;
// TODO: Assert that buffer_out.count == buffer_in.count.
for(size_t i=0; i<buffer_out.count; i++) {
const int32_t output_sample = execute_sample(buffer_in.p[i]);
x_[0] = x_[1];
x_[1] = x_[2];
x_[2] = buffer_in.p[i];
y_[0] = y_[1];
y_[1] = y_[2];
y_[2] = b_[0] * x_[2] + b_[1] * x_[1] + b_[2] * x_[0]
- a_[1] * y_[1] - a_[2] * y_[0];
const int32_t output_sample = y_[2];
const int32_t output_sample_saturated = __SSAT(output_sample, 16);
buffer_out.p[i] = output_sample_saturated;
}
x = x_;
y = y_;
}
void IIRBiquadFilter::execute_in_place(const buffer_s16_t& buffer) {
execute(buffer, buffer);
}
float IIRBiquadFilter::execute_sample(const float in) {
x[0] = x[1];
x[1] = x[2];
x[2] = in;
y[0] = y[1];
y[1] = y[2];
y[2] = config.b[0] * x[2] + config.b[1] * x[1] + config.b[2] * x[0]
- config.a[1] * y[1] - config.a[2] * y[0];
return y[2];
}

2
firmware/baseband/dsp_iir.hpp
View File

@ -65,8 +65,6 @@ private:
iir_biquad_config_t config;
std::array<float, 3> x { { 0.0f, 0.0f, 0.0f } };
std::array<float, 3> y { { 0.0f, 0.0f, 0.0f } };
float execute_sample(const float in);
};
#endif/*__DSP_IIR_H__*/