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/*
* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "rtc_base/numerics/exp_filter.h"
#include <cmath>
namespace rtc {
const float ExpFilter::kValueUndefined = -1.0f;
void ExpFilter::Reset(float alpha) {
alpha_ = alpha;
filtered_ = kValueUndefined;
}
float ExpFilter::Apply(float exp, float sample) {
if (filtered_ == kValueUndefined) {
// Initialize filtered value.
filtered_ = sample;
} else if (exp == 1.0) {
filtered_ = alpha_ * filtered_ + (1 - alpha_) * sample;
} else {
float alpha = std::pow(alpha_, exp);
filtered_ = alpha * filtered_ + (1 - alpha) * sample;
}
if (max_ != kValueUndefined && filtered_ > max_) {
filtered_ = max_;
}
return filtered_;
}
void ExpFilter::UpdateBase(float alpha) {
alpha_ = alpha;
}
} // namespace rtc
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