--- jsr166/src/main/java/util/SplittableRandom.java	2013/07/10 15:40:19	1.1
+++ jsr166/src/main/java/util/SplittableRandom.java	2013/07/11 23:14:45	1.5
@@ -40,7 +40,7 @@ import java.util.stream.DoubleStream;
  * A generator of uniform pseudorandom values applicable for use in
  * (among other contexts) isolated parallel computations that may
  * generate subtasks. Class SplittableRandom supports methods for
- * producing pseudorandom nunmbers of type {@code int}, {@code long},
+ * producing pseudorandom numbers of type {@code int}, {@code long},
  * and {@code double} with similar usages as for class
  * {@link java.util.Random} but differs in the following ways: <ul>
  *
@@ -74,6 +74,7 @@ import java.util.stream.DoubleStream;
  * </ul>
  *
  * @author  Guy Steele
+ * @author  Doug Lea
  * @since   1.8
  */
 public class SplittableRandom {
@@ -112,7 +113,7 @@ public class SplittableRandom {
      * The value of gamma differs for each instance across a series of
      * splits, and is generated using a slightly stripped-down variant
      * of the same algorithm, but operating across calls to split(),
-     * not calls to nextLong(): Each instance carries the state of
+     * not calls to nextSeed(): Each instance carries the state of
      * this generator as nextSplit, and uses mix64(nextSplit) as its
      * own gamma value. Computations of gammas themselves use a fixed
      * constant as the second argument to the addGammaModGeorge
@@ -177,6 +178,12 @@ public class SplittableRandom {
     private static final long DEFAULT_SEED_GAMMA = 0xBD24B73A95FB84D9L;
 
     /**
+     * The least non-zero value returned by nextDouble(). This value
+     * is scaled by a random value of 53 bits to produce a result.
+     */
+    private static final double DOUBLE_UNIT = 1.0 / (1L << 53);
+
+    /**
      * The next seed for default constructors.
      */
     private static final AtomicLong defaultSeedGenerator =
@@ -310,12 +317,16 @@ public class SplittableRandom {
          * evenly divisible by the range. The loop rejects candidates
          * computed from otherwise over-represented values.  The
          * expected number of iterations under an ideal generator
-         * varies from 1 to 2, depending on the bound.
+         * varies from 1 to 2, depending on the bound. The loop itself
+         * takes an unlovable form. Because the first candidate is
+         * already available, we need a break-in-the-middle
+         * construction, which is concisely but cryptically performed
+         * within the while-condition of a body-less for loop.
          *
          * 4. Otherwise, the range cannot be represented as a positive
-         * long.  Repeatedly generate unbounded longs until obtaining
-         * a candidate meeting constraints (with an expected number of
-         * iterations of less than two).
+         * long.  The loop repeatedly generates unbounded longs until
+         * obtaining a candidate meeting constraints (with an expected
+         * number of iterations of less than two).
          */
 
         long r = mix64(nextSeed());
@@ -375,8 +386,7 @@ public class SplittableRandom {
      * @return a pseudorandom value
      */
     final double internalNextDouble(double origin, double bound) {
-        long bits = (1023L << 52) | (nextLong() >>> 12);
-        double r = Double.longBitsToDouble(bits) - 1.0;
+        double r = (nextLong() >>> 11) * DOUBLE_UNIT;
         if (origin < bound) {
             r = r * (bound - origin) + origin;
             if (r == bound) // correct for rounding
@@ -540,8 +550,7 @@ public class SplittableRandom {
      * (inclusive) and {@code 1.0} (exclusive)
      */
     public double nextDouble() {
-        long bits = (1023L << 52) | (nextLong() >>> 12);
-        return Double.longBitsToDouble(bits) - 1.0;
+        return (nextLong() >>> 11) * DOUBLE_UNIT;
     }
 
     /**
@@ -752,7 +761,8 @@ public class SplittableRandom {
 
     /**
      * Returns a stream with the given {@code streamSize} number of
-     * pseudorandom {@code double} values.
+     * pseudorandom {@code double} values, each between {@code 0.0}
+     * (inclusive) and {@code 1.0} (exclusive).
      *
      * @param streamSize the number of values to generate
      * @return a stream of {@code double} values
@@ -770,7 +780,8 @@ public class SplittableRandom {
 
     /**
      * Returns an effectively unlimited stream of pseudorandom {@code
-     * double} values.
+     * double} values, each between {@code 0.0} (inclusive) and {@code
+     * 1.0} (exclusive).
      *
      * @implNote This method is implemented to be equivalent to {@code
      * doubles(Long.MAX_VALUE)}.
@@ -866,8 +877,7 @@ public class SplittableRandom {
 
         public int characteristics() {
             return (Spliterator.SIZED | Spliterator.SUBSIZED |
-                    Spliterator.ORDERED | Spliterator.NONNULL |
-                    Spliterator.IMMUTABLE);
+                    Spliterator.NONNULL | Spliterator.IMMUTABLE);
         }
 
         public boolean tryAdvance(IntConsumer consumer) {
@@ -921,8 +931,7 @@ public class SplittableRandom {
 
         public int characteristics() {
             return (Spliterator.SIZED | Spliterator.SUBSIZED |
-                    Spliterator.ORDERED | Spliterator.NONNULL |
-                    Spliterator.IMMUTABLE);
+                    Spliterator.NONNULL | Spliterator.IMMUTABLE);
         }
 
         public boolean tryAdvance(LongConsumer consumer) {
@@ -977,8 +986,7 @@ public class SplittableRandom {
 
         public int characteristics() {
             return (Spliterator.SIZED | Spliterator.SUBSIZED |
-                    Spliterator.ORDERED | Spliterator.NONNULL |
-                    Spliterator.IMMUTABLE);
+                    Spliterator.NONNULL | Spliterator.IMMUTABLE);
         }
 
         public boolean tryAdvance(DoubleConsumer consumer) {