c62642c7a6
This improves self-fairness and competing for resources with TCP flows. BUG=4711 Review URL: https://codereview.webrtc.org/1151603008 Cr-Commit-Position: refs/heads/master@{#9545}
42 lines
1.3 KiB
C++
42 lines
1.3 KiB
C++
/*
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* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "webrtc/modules/remote_bitrate_estimator/test/random.h"
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#include <math.h>
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namespace webrtc {
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Random::Random(uint32_t seed) : a_(0x531FDB97 ^ seed), b_(0x6420ECA8 + seed) {
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}
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float Random::Rand() {
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const float kScale = 1.0f / 0xffffffff;
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float result = kScale * b_;
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a_ ^= b_;
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b_ += a_;
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return result;
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}
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int Random::Gaussian(int mean, int standard_deviation) {
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// Creating a Normal distribution variable from two independent uniform
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// variables based on the Box-Muller transform, which is defined on the
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// interval (0, 1], hence the mask+add below.
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const double kPi = 3.14159265358979323846;
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const double kScale = 1.0 / 0x80000000ul;
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double u1 = kScale * ((a_ & 0x7ffffffful) + 1);
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double u2 = kScale * ((b_ & 0x7ffffffful) + 1);
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a_ ^= b_;
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b_ += a_;
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return static_cast<int>(
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mean + standard_deviation * sqrt(-2 * log(u1)) * cos(2 * kPi * u2));
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}
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} // namespace webrtc
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