| /* |
| * Copyright (c) 2015 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. |
| */ |
| |
| #ifndef WEBRTC_BASE_RANDOM_H_ |
| #define WEBRTC_BASE_RANDOM_H_ |
| |
| #include <limits> |
| |
| #include "webrtc/typedefs.h" |
| #include "webrtc/base/constructormagic.h" |
| #include "webrtc/base/checks.h" |
| |
| namespace webrtc { |
| |
| class Random { |
| public: |
| explicit Random(uint64_t seed); |
| |
| // Return pseudo-random integer of the specified type. |
| // We need to limit the size to 32 bits to keep the output close to uniform. |
| template <typename T> |
| T Rand() { |
| static_assert(std::numeric_limits<T>::is_integer && |
| std::numeric_limits<T>::radix == 2 && |
| std::numeric_limits<T>::digits <= 32, |
| "Rand is only supported for built-in integer types that are " |
| "32 bits or smaller."); |
| return static_cast<T>(NextOutput()); |
| } |
| |
| // Uniformly distributed pseudo-random number in the interval [0, t]. |
| uint32_t Rand(uint32_t t); |
| |
| // Uniformly distributed pseudo-random number in the interval [low, high]. |
| uint32_t Rand(uint32_t low, uint32_t high); |
| |
| // Uniformly distributed pseudo-random number in the interval [low, high]. |
| int32_t Rand(int32_t low, int32_t high); |
| |
| // Normal Distribution. |
| double Gaussian(double mean, double standard_deviation); |
| |
| // Exponential Distribution. |
| double Exponential(double lambda); |
| |
| private: |
| // Outputs a nonzero 64-bit random number. |
| uint64_t NextOutput() { |
| state_ ^= state_ >> 12; |
| state_ ^= state_ << 25; |
| state_ ^= state_ >> 27; |
| RTC_DCHECK(state_ != 0x0ULL); |
| return state_ * 2685821657736338717ull; |
| } |
| |
| uint64_t state_; |
| |
| RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(Random); |
| }; |
| |
| // Return pseudo-random number in the interval [0.0, 1.0). |
| template <> |
| float Random::Rand<float>(); |
| |
| // Return pseudo-random number in the interval [0.0, 1.0). |
| template <> |
| double Random::Rand<double>(); |
| |
| // Return pseudo-random boolean value. |
| template <> |
| bool Random::Rand<bool>(); |
| |
| } // namespace webrtc |
| |
| #endif // WEBRTC_BASE_RANDOM_H_ |