| // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| import "dart:typed_data"; |
| |
| // A VM patch of the dart:math library. |
| |
| // If [x] is an [int] and [exponent] is a non-negative [int], the result is |
| // an [int], otherwise the result is a [double]. |
| patch num pow(num x, num exponent) { |
| if ((x is int) && (exponent is int) && (exponent >= 0)) { |
| return x.pow(exponent); |
| } |
| // Double.pow will call exponent.toDouble(). |
| return x.toDouble().pow(exponent); |
| } |
| |
| patch double atan2(num a, num b) => _atan2(a.toDouble(), b.toDouble()); |
| patch double sin(num value) => _sin(value.toDouble()); |
| patch double cos(num value) => _cos(value.toDouble()); |
| patch double tan(num value) => _tan(value.toDouble()); |
| patch double acos(num value) => _acos(value.toDouble()); |
| patch double asin(num value) => _asin(value.toDouble()); |
| patch double atan(num value) => _atan(value.toDouble()); |
| patch double sqrt(num value) => _sqrt(value.toDouble()); |
| patch double exp(num value) => _exp(value.toDouble()); |
| patch double log(num value) => _log(value.toDouble()); |
| |
| double _atan2(double a, double b) native "Math_atan2"; |
| double _sin(double x) native "Math_sin"; |
| double _cos(double x) native "Math_cos"; |
| double _tan(double x) native "Math_tan"; |
| double _acos(double x) native "Math_acos"; |
| double _asin(double x) native "Math_asin"; |
| double _atan(double x) native "Math_atan"; |
| double _sqrt(double x) native "Math_sqrt"; |
| double _exp(double x) native "Math_exp"; |
| double _log(double x) native "Math_log"; |
| |
| |
| // TODO(iposva): Handle patch methods within a patch class correctly. |
| patch class Random { |
| |
| /*patch*/ factory Random([int seed]) { |
| if (seed == null) { |
| seed = _Random._nextSeed(); |
| } |
| do { |
| seed = (seed + 0x5A17) & _Random._MASK_64; |
| } while (seed == 0); |
| // Crank a couple of times to distribute the seed bits a bit further. |
| return new _Random._internal(seed).._nextState() |
| .._nextState() |
| .._nextState() |
| .._nextState(); |
| } |
| } |
| |
| |
| class _Random implements Random { |
| // Internal state of the random number generator. |
| final _state = new Uint32List(2); |
| static const kSTATE_LO = 0; |
| static const kSTATE_HI = 1; |
| |
| _Random._internal(state) { |
| _state[kSTATE_LO] = state & _MASK_32; |
| _state[kSTATE_HI] = state >> 32; |
| } |
| |
| // The algorithm used here is Multiply with Carry (MWC) with a Base b = 2^32. |
| // http://en.wikipedia.org/wiki/Multiply-with-carry |
| // The constant A is selected from "Numerical Recipes 3rd Edition" p.348 B1. |
| void _nextState() { |
| var state = ((_A * (_state[kSTATE_LO])) + _state[kSTATE_HI]) & _MASK_64; |
| _state[kSTATE_LO] = state & _MASK_32; |
| _state[kSTATE_HI] = state >> 32; |
| } |
| |
| int nextInt(int max) { |
| // TODO(srdjan): Remove the 'limit' check once optimizing comparison of |
| // Smi-s with Mint constants. |
| final limit = 0x3FFFFFFF; |
| if (max <= 0 || ((max > limit) && (max > _POW2_32))) { |
| throw new ArgumentError("max must be positive and < 2^32:" |
| " $max"); |
| } |
| if ((max & -max) == max) { |
| // Fast case for powers of two. |
| _nextState(); |
| return _state[kSTATE_LO] & (max - 1); |
| } |
| |
| var rnd32; |
| var result; |
| do { |
| _nextState(); |
| rnd32 = _state[kSTATE_LO]; |
| result = rnd32 % max; |
| } while ((rnd32 - result + max) >= _POW2_32); |
| return result; |
| } |
| |
| double nextDouble() { |
| return ((nextInt(1 << 26) << 27) + nextInt(1 << 27)) / _POW2_53_D; |
| } |
| |
| bool nextBool() { |
| return nextInt(2) == 0; |
| } |
| |
| // Constants used by the algorithm or masking. |
| static const _MASK_32 = (1 << 32) - 1; |
| static const _MASK_64 = (1 << 64) - 1; |
| static const _POW2_32 = 1 << 32; |
| static const _POW2_53_D = 1.0 * (1 << 53); |
| |
| static const _A = 0xffffda61; |
| |
| // Use a singleton Random object to get a new seed if no seed was passed. |
| static var _prng = null; |
| |
| static int _nextSeed() { |
| if (_prng == null) { |
| // TODO(iposva): Use system to get a random seed. |
| _prng = new Random(new DateTime.now().millisecondsSinceEpoch); |
| } |
| // Trigger the PRNG once to change the internal state. |
| _prng._nextState(); |
| return _prng._state[kSTATE_LO]; |
| } |
| } |