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| 1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
| 2 // for details. All rights reserved. Use of this source code is governed by a | 2 // for details. All rights reserved. Use of this source code is governed by a |
| 3 // BSD-style license that can be found in the LICENSE file. | 3 // BSD-style license that can be found in the LICENSE file. |
| 4 | 4 |
| 5 import "dart:typed_data"; | 5 import "dart:typed_data"; |
| 6 | 6 |
| 7 // A VM patch of the dart:math library. | 7 // A VM patch of the dart:math library. |
| 8 | 8 |
| 9 // If [x] is an [int] and [exponent] is a non-negative [int], the result is | 9 // If [x] is an [int] and [exponent] is a non-negative [int], the result is |
| 10 // an [int], otherwise the result is a [double]. | 10 // an [int], otherwise the result is a [double]. |
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| 92 } | 92 } |
| 93 | 93 |
| 94 @patch factory Random.secure() { | 94 @patch factory Random.secure() { |
| 95 return new _SecureRandom(); | 95 return new _SecureRandom(); |
| 96 } | 96 } |
| 97 } | 97 } |
| 98 | 98 |
| 99 | 99 |
| 100 class _Random implements Random { | 100 class _Random implements Random { |
| 101 // Internal state of the random number generator. | 101 // Internal state of the random number generator. |
| 102 final _state; | 102 final _state; |
|
Vyacheslav Egorov (Google)
2017/02/17 13:08:52
Uint32List _state
ahe
2017/02/17 13:38:28
Done.
| |
| 103 static const _kSTATE_LO = 0; | 103 static const _kSTATE_LO = 0; |
| 104 static const _kSTATE_HI = 1; // Unused in Dart code. | 104 static const _kSTATE_HI = 1; // Unused in Dart code. |
| 105 | 105 |
| 106 _Random._withState(Uint32List this._state); | 106 _Random._withState(this._state); |
| 107 | 107 |
| 108 // The algorithm used here is Multiply with Carry (MWC) with a Base b = 2^32. | 108 // The algorithm used here is Multiply with Carry (MWC) with a Base b = 2^32. |
| 109 // http://en.wikipedia.org/wiki/Multiply-with-carry | 109 // http://en.wikipedia.org/wiki/Multiply-with-carry |
| 110 // The constant A is selected from "Numerical Recipes 3rd Edition" p.348 B1. | 110 // The constant A is selected from "Numerical Recipes 3rd Edition" p.348 B1. |
| 111 | 111 |
| 112 // Implements: | 112 // Implements: |
| 113 // var state = | 113 // var state = |
| 114 // ((_A * (_state[_kSTATE_LO])) + _state[_kSTATE_HI]) & ((1 << 64) - 1); | 114 // ((_A * (_state[_kSTATE_LO])) + _state[_kSTATE_HI]) & ((1 << 64) - 1); |
| 115 // _state[_kSTATE_LO] = state & ((1 << 32) - 1); | 115 // _state[_kSTATE_LO] = state & ((1 << 32) - 1); |
| 116 // _state[_kSTATE_HI] = state >> 32; | 116 // _state[_kSTATE_HI] = state >> 32; |
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| 205 | 205 |
| 206 bool nextBool() { | 206 bool nextBool() { |
| 207 return _getBytes(1).isEven; | 207 return _getBytes(1).isEven; |
| 208 } | 208 } |
| 209 | 209 |
| 210 // Constants used by the algorithm. | 210 // Constants used by the algorithm. |
| 211 static const _POW2_32 = 1 << 32; | 211 static const _POW2_32 = 1 << 32; |
| 212 static const _POW2_53_D = 1.0 * (1 << 53); | 212 static const _POW2_53_D = 1.0 * (1 << 53); |
| 213 } | 213 } |
| 214 | 214 |
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