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 // 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 _intPow(x, exponent); } return _doublePow(x.toDouble(), exponent.toDouble()); } double _doublePow(double base, double exponent) { if (exponent == 0.0) { return 1.0; // ECMA-262 15.8.2.13 } // Speed up simple cases. if (exponent == 1.0) return base; if (exponent == 2.0) return base * base; if (exponent == 3.0) return base * base * base; if (base == 1.0) return 1.0; if (base.isNaN || exponent.isNaN) { return double.NAN; } if ((base != -double.INFINITY) && (exponent == 0.5)) { if (base == 0.0) { return 0.0; } return sqrt(base); } return _pow(base.toDouble(), exponent.toDouble()); } double _pow(double base, double exponent) native "Math_doublePow"; int _intPow(int base, int exponent) { // Exponentiation by squaring. int result = 1; while (exponent != 0) { if ((exponent & 1) == 1) { result *= base; } exponent >>= 1; // Skip unnecessary operation (can overflow to Mint or Bigint). if (exponent != 0) { base *= base; } } return result; } @patch double atan2(num a, num b) => _atan2(a.toDouble(), b.toDouble()); @patch double sin(num x) => _sin(x.toDouble()); @patch double cos(num x) => _cos(x.toDouble()); @patch double tan(num x) => _tan(x.toDouble()); @patch double acos(num x) => _acos(x.toDouble()); @patch double asin(num x) => _asin(x.toDouble()); @patch double atan(num x) => _atan(x.toDouble()); @patch double sqrt(num x) => _sqrt(x.toDouble()); @patch double exp(num x) => _exp(x.toDouble()); @patch double log(num x) => _log(x.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]) { var state = _Random._setupSeed((seed == null) ? _Random._nextSeed() : seed); // Crank a couple of times to distribute the seed bits a bit further. return new _Random._withState(state).._nextState() .._nextState() .._nextState() .._nextState(); } @patch factory Random.secure() { return new _SecureRandom(); } } class _Random implements Random { // Internal state of the random number generator. final _state; static const _kSTATE_LO = 0; static const _kSTATE_HI = 1; // Unused in Dart code. _Random._withState(Uint32List this._state); // 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. // Implements: // var state = // ((_A * (_state[_kSTATE_LO])) + _state[_kSTATE_HI]) & ((1 << 64) - 1); // _state[_kSTATE_LO] = state & ((1 << 32) - 1); // _state[_kSTATE_HI] = state >> 32; // This is a native to prevent 64-bit operations in Dart, which // fail with --throw_on_javascript_int_overflow. // TODO(regis): Implement in Dart and remove Random_nextState in math.cc. void _nextState() native "Random_nextState"; int nextInt(int max) { const limit = 0x3FFFFFFF; if ((max <= 0) || ((max > limit) && (max > _POW2_32))) { throw new RangeError.range(max, 1, _POW2_32, "max", "Must be positive and <= 2^32"); } 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) * _POW2_27_D) + nextInt(1 << 27)) / _POW2_53_D; } bool nextBool() { return nextInt(2) == 0; } // Constants used by the algorithm. static const _POW2_32 = 1 << 32; static const _POW2_53_D = 1.0 * (1 << 53); static const _POW2_27_D = 1.0 * (1 << 27); static const _A = 0xffffda61; // Use a singleton Random object to get a new seed if no seed was passed. static var _prng = new _Random._withState(_initialSeed()); // This is a native to prevent 64-bit operations in Dart, which // fail with --throw_on_javascript_int_overflow. // TODO(regis): Implement here in Dart and remove native in math.cc. static Uint32List _setupSeed(int seed) native "Random_setupSeed"; // Get a seed from the VM's random number provider. static Uint32List _initialSeed() native "Random_initialSeed"; static int _nextSeed() { // Trigger the PRNG once to change the internal state. _prng._nextState(); return _prng._state[_kSTATE_LO]; } } class _SecureRandom implements Random { _SecureRandom() { // Throw early in constructor if entropy source is not hooked up. _getBytes(1); } // Return count bytes of entropy as a positive integer; count <= 8. static int _getBytes(int count) native "SecureRandom_getBytes"; int nextInt(int max) { RangeError.checkValueInInterval( max, 1, _POW2_32, "max", "Must be positive and <= 2^32"); final byteCount = ((max - 1).bitLength + 7) >> 3; if (byteCount == 0) { return 0; // Not random if max == 1. } var rnd; var result; do { rnd = _getBytes(byteCount); result = rnd % max; } while ((rnd - result + max) > (1 << (byteCount << 3))); return result; } double nextDouble() { return (_getBytes(7) >> 3) / _POW2_53_D; } bool nextBool() { return _getBytes(1).isEven; } // Constants used by the algorithm. static const _POW2_32 = 1 << 32; static const _POW2_53_D = 1.0 * (1 << 53); }