NucleoTNC/TNC/IirFilter.hpp

54 wiersze
1011 B
C++

// Copyright 2015-2021 Rob Riggs <rob@mobilinkd.com>
// All rights reserved.
#pragma once
#include <array>
#include <cstring>
#include <cstddef>
namespace mobilinkd { namespace tnc {
template <size_t N>
struct IirFilter {
const std::array<float, N>& numerator_;
const std::array<float, N>& denominator_;
std::array<float, N> history_;
IirFilter(const std::array<float, N>& b,
const std::array<float, N>& a)
: numerator_(b), denominator_(a)
, history_()
{
history_.fill(0.0f);
}
~IirFilter() {}
static constexpr size_t size() { return N; }
void reset() { history_.fill(0.0f); }
float operator()(float input)
{
for (size_t i = N - 1; i != 0; i--) history_[i] = history_[i - 1];
history_[0] = input;
for (size_t i = 1; i != N; i++) {
history_[0] -= denominator_[i] * history_[i];
}
float result = 0;
for (size_t i = 0; i != N; i++) {
result += numerator_[i] * history_[i];
}
return result;
}
};
}} // mobilinkd::tnc