Port FluidSim core and scenarios to C++20

src/audio_output_stream.cpp

@@ -0,0 +1,36 @@
+#include "FluidSim/AudioOutputStream.hpp"
+
+#include <algorithm>
+#include <cmath>
+
+namespace fluidsim::port {
+
+AudioOutputStream::AudioOutputStream(SimulationRingBuffer& ring, unsigned int sample_rate)
+    : ring_(ring) {
+    initialize(2, sample_rate, {sf::SoundChannel::FrontLeft, sf::SoundChannel::FrontRight});
+}
+
+bool AudioOutputStream::onGetData(Chunk& data) {
+    const std::size_t read = ring_.read_interpolated(temp_left_, temp_right_, speed());
+    constexpr float dc_coefficient = 0.9995f;
+    for (std::size_t i = 0; i < read; ++i) {
+        const float left = temp_left_[i] - previous_input_left_ + dc_coefficient * previous_output_left_;
+        const float right = temp_right_[i] - previous_input_right_ + dc_coefficient * previous_output_right_;
+        previous_input_left_ = temp_left_[i];
+        previous_input_right_ = temp_right_[i];
+        previous_output_left_ = left;
+        previous_output_right_ = right;
+        const float finite_left = std::isfinite(left) ? std::clamp(left, -1.0f, 1.0f) : 0.0f;
+        const float finite_right = std::isfinite(right) ? std::clamp(right, -1.0f, 1.0f) : 0.0f;
+        output_[i * 2] = static_cast<std::int16_t>(finite_left * 32767.0f);
+        output_[i * 2 + 1] = static_cast<std::int16_t>(finite_right * 32767.0f);
+    }
+    std::fill(output_.begin() + static_cast<std::ptrdiff_t>(read * 2), output_.end(), 0);
+    data.samples = output_.data();
+    data.sampleCount = output_.size();
+    return true;
+}
+
+void AudioOutputStream::onSeek(sf::Time /*time_offset*/) {}
+
+} // namespace fluidsim::port