- Avoid going into BigInteger domain for most of the Random state calculation.

lib/math_patch.dart

 // 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.
 
 // A VM patch of the dart:math library.
 patch num pow(num x, num exponent) => MathNatives.pow(x, exponent);
 patch double atan2(num a, num b) => MathNatives.atan2(a, b);
 patch double sin(num x) => MathNatives.sin(x);
 patch double cos(num x) => MathNatives.cos(x);
 patch double tan(num x) => MathNatives.tan(x);
@@ skipping 15 matching lines @@
     do {
       seed = (seed + 0x5A17) & _Random._MASK_64;
     } while (seed == 0);
     return new _Random._internal(seed);
   }
 }
 
 
 class _Random implements Random {
   // Internal state of the random number generator.
-  var _state;
+  var _state_lo;
+  var _state_hi;
 
-  _Random._internal(this._state);
+  _Random._internal(state)

[srdjan, 2012/10/30 00:16:58]

you can type this int.

+      : _state_lo = (state & _MASK_32), _state_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.
   int _nextInt32() {
-    _state = ((_A * (_state & _MASK_32)) + (_state >> 32)) & _MASK_64;
-    return _state & _MASK_32;
+    var state = ((_A * (_state_lo)) + _state_hi) & _MASK_64;
+    _state_lo = state & _MASK_32;
+    _state_hi = state >> 32;
+    return _state_lo;
   }
 
   int nextInt(int max) {
     if (max <= 0 || max > _POW2_32) {
       throw new ArgumentError("max must be positive and < 2^32:"
                                          " $max");
     }
     if ((max & -max) == max) {
       // Fast case for powers of two.
       return _nextInt32() & (max - 1);
@@ skipping 26 matching lines @@
 
   // 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 Date.now().millisecondsSinceEpoch);
     }
     // Trigger the PRNG once to change the internal state.
-    _prng._nextInt32();
-    return _prng._state;
+    return _prng._nextInt32();
   }
 }