Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
       3             :  *
       4             :  *  Use of this source code is governed by a BSD-style license
       5             :  *  that can be found in the LICENSE file in the root of the source
       6             :  *  tree. An additional intellectual property rights grant can be found
       7             :  *  in the file PATENTS.  All contributing project authors may
       8             :  *  be found in the AUTHORS file in the root of the source tree.
       9             :  */
      10             : 
      11             : #include "webrtc/base/numerics/exp_filter.h"
      12             : 
      13             : #include <math.h>
      14             : 
      15             : namespace rtc {
      16             : 
      17             : const float ExpFilter::kValueUndefined = -1.0f;
      18             : 
      19           0 : void ExpFilter::Reset(float alpha) {
      20           0 :   alpha_ = alpha;
      21           0 :   filtered_ = kValueUndefined;
      22           0 : }
      23             : 
      24           0 : float ExpFilter::Apply(float exp, float sample) {
      25           0 :   if (filtered_ == kValueUndefined) {
      26             :     // Initialize filtered value.
      27           0 :     filtered_ = sample;
      28           0 :   } else if (exp == 1.0) {
      29           0 :     filtered_ = alpha_ * filtered_ + (1 - alpha_) * sample;
      30             :   } else {
      31           0 :     float alpha = pow(alpha_, exp);
      32           0 :     filtered_ = alpha * filtered_ + (1 - alpha) * sample;
      33             :   }
      34           0 :   if (max_ != kValueUndefined && filtered_ > max_) {
      35           0 :     filtered_ = max_;
      36             :   }
      37           0 :   return filtered_;
      38             : }
      39             : 
      40           0 : void ExpFilter::UpdateBase(float alpha) {
      41           0 :   alpha_ = alpha;
      42           0 : }
      43             : }  // namespace rtc