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1 // Copyright 2015 The Chromium Authors. All rights reserved. | 1 // Copyright 2015 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef MEDIA_BASE_MOVING_AVERAGE_H_ | 5 #ifndef MEDIA_BASE_MOVING_AVERAGE_H_ |
6 #define MEDIA_BASE_MOVING_AVERAGE_H_ | 6 #define MEDIA_BASE_MOVING_AVERAGE_H_ |
7 | 7 |
8 #include <vector> | 8 #include <vector> |
9 | 9 |
10 #include "base/time/time.h" | 10 #include "base/time/time.h" |
11 #include "media/base/media_export.h" | 11 #include "media/base/media_export.h" |
12 | 12 |
13 namespace media { | 13 namespace media { |
14 | 14 |
15 // Simple class for calculating a moving average of fixed size. | 15 // Simple class for calculating a moving average of fixed size. |
16 class MEDIA_EXPORT MovingAverage { | 16 class MEDIA_EXPORT MovingAverage { |
17 public: | 17 public: |
18 // Creates a MovingAverage instance with space for |depth| samples. | 18 // Creates a MovingAverage instance with space for |depth| samples. |
19 explicit MovingAverage(size_t depth); | 19 explicit MovingAverage(size_t depth); |
20 ~MovingAverage(); | 20 ~MovingAverage(); |
21 | 21 |
22 // Adds a new sample to the average; replaces the oldest sample if |depth_| | 22 // Adds a new sample to the average; replaces the oldest sample if |depth_| |
23 // has been exceeded. Updates |total_| to the new sum of values. | 23 // has been exceeded. Updates |total_| to the new sum of values. |
24 void AddSample(base::TimeDelta sample); | 24 void AddSample(base::TimeDelta sample); |
25 | 25 |
26 // Returns the current average of all held samples. | 26 // Returns the current average of all held samples. |
27 base::TimeDelta Average() const; | 27 base::TimeDelta Average() const; |
28 | 28 |
| 29 // Returns the standard deviation of all held samples. |
| 30 base::TimeDelta Deviation() const; |
| 31 |
29 // Resets the state of the class to its initial post-construction state. | 32 // Resets the state of the class to its initial post-construction state. |
30 void Reset(); | 33 void Reset(); |
31 | 34 |
32 size_t count() const { return count_; } | 35 size_t count() const { return count_; } |
33 | 36 |
34 private: | 37 private: |
35 // Maximum number of elements allowed in the average. | 38 // Maximum number of elements allowed in the average. |
36 const size_t depth_; | 39 const size_t depth_; |
37 | 40 |
38 // Number of elements seen thus far. | 41 // Number of elements seen thus far. |
39 uint64_t count_; | 42 uint64_t count_; |
40 | 43 |
41 std::vector<base::TimeDelta> samples_; | 44 std::vector<base::TimeDelta> samples_; |
42 base::TimeDelta total_; | 45 base::TimeDelta total_; |
| 46 uint64_t square_sum_us_; |
43 | 47 |
44 DISALLOW_COPY_AND_ASSIGN(MovingAverage); | 48 DISALLOW_COPY_AND_ASSIGN(MovingAverage); |
45 }; | 49 }; |
46 | 50 |
47 } // namespace media | 51 } // namespace media |
48 | 52 |
49 #endif // MEDIA_BASE_MOVING_AVERAGE_H_ | 53 #endif // MEDIA_BASE_MOVING_AVERAGE_H_ |
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