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1 /* | 1 /* |
2 * Copyright (c) 2016 The WebRTC project authors. All Rights Reserved. | 2 * Copyright (c) 2016 The WebRTC project authors. All Rights Reserved. |
3 * | 3 * |
4 * Use of this source code is governed by a BSD-style license | 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 | 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 | 6 * tree. An additional intellectual property rights grant can be found |
7 * in the file PATENTS. All contributing project authors may | 7 * in the file PATENTS. All contributing project authors may |
8 * be found in the AUTHORS file in the root of the source tree. | 8 * be found in the AUTHORS file in the root of the source tree. |
9 */ | 9 */ |
10 | 10 |
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84 // can be set. The unwrapped value is not allowed to wrap. | 84 // can be set. The unwrapped value is not allowed to wrap. |
85 template <typename T, T M = 0> | 85 template <typename T, T M = 0> |
86 class SeqNumUnwrapper { | 86 class SeqNumUnwrapper { |
87 // Use '<' instead of rtc::SafeLt to avoid crbug.com/753488 | 87 // Use '<' instead of rtc::SafeLt to avoid crbug.com/753488 |
88 static_assert( | 88 static_assert( |
89 std::is_unsigned<T>::value && | 89 std::is_unsigned<T>::value && |
90 std::numeric_limits<T>::max() < std::numeric_limits<uint64_t>::max(), | 90 std::numeric_limits<T>::max() < std::numeric_limits<uint64_t>::max(), |
91 "Type unwrapped must be an unsigned integer smaller than uint64_t."); | 91 "Type unwrapped must be an unsigned integer smaller than uint64_t."); |
92 | 92 |
93 public: | 93 public: |
94 // We want a value that is close to 2^63 for two reasons. Firstly, we | 94 // We want a default value that is close to 2^62 for a two reasons. Firstly, |
95 // can unwrap wrapping numbers in either direction, and secondly, we avoid | 95 // we can unwrap wrapping numbers in either direction, and secondly, the |
96 // causing a crash on bad input. We also want the default value to be somewhat | 96 // unwrapped numbers can be stored in either int64_t or uint64_t. We also want |
97 // human readable, a power of 10 for example. | 97 // the default value to be human readable, which makes a power of 10 suitable. |
98 static constexpr uint64_t kDefaultStartValue = 10000000000000000000UL; | 98 static constexpr uint64_t kDefaultStartValue = 1000000000000000000UL; |
philipel
2017/09/08 09:43:54
I removed one '0' to make the default value fit in
| |
99 | 99 |
100 SeqNumUnwrapper() : last_unwrapped_(kDefaultStartValue) {} | 100 SeqNumUnwrapper() : last_unwrapped_(kDefaultStartValue) {} |
101 explicit SeqNumUnwrapper(uint64_t start_at) : last_unwrapped_(start_at) {} | 101 explicit SeqNumUnwrapper(uint64_t start_at) : last_unwrapped_(start_at) {} |
102 | 102 |
103 uint64_t Unwrap(T value) { | 103 uint64_t Unwrap(T value) { |
104 if (!last_value_) | 104 if (!last_value_) |
105 last_value_.emplace(value); | 105 last_value_.emplace(value); |
106 | 106 |
107 uint64_t unwrapped = 0; | 107 uint64_t unwrapped = 0; |
108 if (AheadOrAt<T, M>(value, *last_value_)) { | 108 if (AheadOrAt<T, M>(value, *last_value_)) { |
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119 } | 119 } |
120 | 120 |
121 private: | 121 private: |
122 uint64_t last_unwrapped_; | 122 uint64_t last_unwrapped_; |
123 rtc::Optional<T> last_value_; | 123 rtc::Optional<T> last_value_; |
124 }; | 124 }; |
125 | 125 |
126 } // namespace webrtc | 126 } // namespace webrtc |
127 | 127 |
128 #endif // WEBRTC_MODULES_VIDEO_CODING_SEQUENCE_NUMBER_UTIL_H_ | 128 #endif // WEBRTC_MODULES_VIDEO_CODING_SEQUENCE_NUMBER_UTIL_H_ |
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