25 

    25 

    26 package java.util.random;

    26 package java.util.random;

    27 

    27 

    28 import java.math.BigInteger;

    28 import java.math.BigInteger;

    29 import java.util.concurrent.atomic.AtomicLong;

    29 import java.util.concurrent.atomic.AtomicLong;

    30 

    32 

    31 /**

    33 /**

    32  * A generator of uniform pseudorandom values applicable for use in

    34  * A generator of uniform pseudorandom values applicable for use in

    33  * (among other contexts) isolated parallel computations that may

    35  * (among other contexts) isolated parallel computations that may

    34  * generate subtasks.  Class {@link MRG32k3a} implements

    36  * generate subtasks.  Class {@link MRG32k3a} implements

    36  * and therefore supports methods for producing pseudorandomly chosen

    38  * and therefore supports methods for producing pseudorandomly chosen

    37  * numbers of type {@code int}, {@code long}, {@code float}, and {@code double}

    39  * numbers of type {@code int}, {@code long}, {@code float}, and {@code double}

    38  * as well as creating new {@link Xoroshiro128PlusMRG32k3a} objects

    40  * as well as creating new {@link Xoroshiro128PlusMRG32k3a} objects

    39  * by "jumping" or "leaping".

    41  * by "jumping" or "leaping".

    40  * <p>

    42  * <p>

    51  * seed unless the {@linkplain System#getProperty system property}

    53  * seed unless the {@linkplain System#getProperty system property}

    52  * {@code java.util.secureRandomSeed} is set to {@code true}.

    54  * {@code java.util.secureRandomSeed} is set to {@code true}.

    53  *

    55  *

    54  * @since 14

    56  * @since 14

    55  */

    57  */

    57 

    59 

    58     /*

    60     /*

    59      * Implementation Overview.

    61      * Implementation Overview.

    60      *

    62      *

    61      * See http://simul.iro.umontreal.ca/rng/MRG32k3a.c .

    63      * See http://simul.iro.umontreal.ca/rng/MRG32k3a.c .

    85 

    87 

    86     /**

    88     /**

    87      * The seed generator for default constructors.

    89      * The seed generator for default constructors.

    88      */

    90      */

    89     private static final AtomicLong DEFAULT_GEN =

    91     private static final AtomicLong DEFAULT_GEN =

    91 

    93 

    92     /*

    94     /*

    93       32-bits Random number generator U(0,1): MRG32k3a

    95       32-bits Random number generator U(0,1): MRG32k3a

    94       Author: Pierre L'Ecuyer,

    96       Author: Pierre L'Ecuyer,

    95       Source: Good Parameter Sets for Combined Multiple Recursive Random

    97       Source: Good Parameter Sets for Combined Multiple Recursive Random

   130                      u + m + ((M1_DEFICIT + 1) >>> 1) - (r = u % n) < 0;

   132                      u + m + ((M1_DEFICIT + 1) >>> 1) - (r = u % n) < 0;

   131                      u = (int)nextDouble() >>> 1)

   133                      u = (int)nextDouble() >>> 1)

   132                     ;

   134                     ;

   133                 return (r + origin);

   135                 return (r + origin);

   134             } else {

   136             } else {

   136             }

   138             }

   137         } else {

   139         } else {

   138             return nextInt();

   140             return nextInt();

   139         }

   141         }

   140     }

   142     }

   217      * generate sequences of values that are statistically independent

   219      * generate sequences of values that are statistically independent

   218      * of those of any other instances in the current program; and

   220      * of those of any other instances in the current program; and

   219      * may, and typically does, vary across program invocations.

   221      * may, and typically does, vary across program invocations.

   220      */

   222      */

   221     public MRG32k3a() {

   223     public MRG32k3a() {

   223     }

   225     }

   224 

   226 

   225     /**

   227     /**

   226      * Creates a new instance of {@link Xoshiro256StarStar} using the specified array of

   228      * Creates a new instance of {@link Xoshiro256StarStar} using the specified array of

   227      * initial seed bytes. Instances of {@link Xoshiro256StarStar} created with the same

   229      * initial seed bytes. Instances of {@link Xoshiro256StarStar} created with the same

   229      *

   231      *

   230      * @param seed the initial seed

   232      * @param seed the initial seed

   231      */

   233      */

   232     public MRG32k3a(byte[] seed) {

   234     public MRG32k3a(byte[] seed) {

   233         // Convert the seed to 6 int values.

   235         // Convert the seed to 6 int values.

   235         int s10 = data[0], s11 = data[1], s12 = data[2];

   237         int s10 = data[0], s11 = data[1], s12 = data[2];

   236         int s20 = data[3], s21 = data[4], s22 = data[5];

   238         int s20 = data[3], s21 = data[4], s22 = data[5];

   237         this.s10 = ((double)(((long)s10) & 0x00000000ffffffffL)) % M1;

   239         this.s10 = ((double)(((long)s10) & 0x00000000ffffffffL)) % M1;

   238         this.s11 = ((double)(((long)s11) & 0x00000000ffffffffL)) % M1;

   240         this.s11 = ((double)(((long)s11) & 0x00000000ffffffffL)) % M1;

   239         this.s12 = ((double)(((long)s12) & 0x00000000ffffffffL)) % M1;

   241         this.s12 = ((double)(((long)s12) & 0x00000000ffffffffL)) % M1;