85 lines
2.4 KiB
C++
85 lines
2.4 KiB
C++
/*
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* smoother.h
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* Copyright (c) 2025 Christopher Herb
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#pragma once
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#include "audio_math.h"
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namespace trnr {
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struct smoother {
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float samplerate;
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float time_samples;
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float current;
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float target;
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float increment;
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int32_t remaining;
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};
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inline void smoother_init(smoother& s, double samplerate, float time_ms,
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float initial_value = 0.0f)
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{
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s.samplerate = fmax(0.0, samplerate);
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s.time_samples = ms_to_samples(time_ms, s.samplerate);
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s.current = initial_value;
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s.target = initial_value;
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s.increment = 0.0f;
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s.remaining = 0;
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}
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inline void smoother_set_target(smoother& s, float newTarget)
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{
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s.target = newTarget;
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// immediate if time is zero or too short
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if (s.time_samples <= 1.0f) {
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s.current = s.target;
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s.increment = 0.0f;
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s.remaining = 0;
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return;
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}
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int32_t n = static_cast<int32_t>(fmax(1.0f, ceilf(s.time_samples)));
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s.remaining = n;
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// protect against denormals / tiny differences, but we want exact reach at the end
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s.increment = (s.target - s.current) / static_cast<float>(s.remaining);
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}
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// process a single sample and return the smoothed value
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inline float smoother_process_sample(smoother& s)
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{
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if (s.remaining > 0) {
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s.current += s.increment;
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--s.remaining;
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if (s.remaining == 0) {
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// ensure exact target at the end to avoid FP drift
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s.current = s.target;
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s.increment = 0.0f;
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}
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}
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return s.current;
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}
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} // namespace trnr
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