hedgehog.random.MersenneTwister64.scala Maven / Gradle / Ivy
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/**
* This is copied from a scalaprops modules here:
*
* https://github.com/scalaprops/scalaprops/blob/f5b9f2edf5987676194f269cedbbfb405bc9d9b0/gen/src/main/scala/scalaprops/MersenneTwister64.scala
*
* Copyright 2015 scalaprops contributors
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
**/
package hedgehog.random
import java.nio.ByteBuffer
import java.util.Arrays
final class MersenneTwister64 private(private val mt0: Array[Long], private val mti0: Int = 313) { // N + 1 = 313
import MersenneTwister64._
override def equals(other: Any): Boolean =
other match {
case that: MersenneTwister64 => this === that
case _ => false
}
override def hashCode = mti0
def ===(that: MersenneTwister64): Boolean =
(this.mti0 == that.mti0) && Arrays.equals(this.mt0, that.mt0)
def next: MersenneTwister64 =
nextLong._1
def getSeedBytes(): Array[Byte] = {
val bytes = new Array[Byte](BYTES)
val bb = ByteBuffer.wrap(bytes)
var i = 0
while(i < N){
bb.putLong(mt0(i))
i += 1
}
bb.putInt(mti0)
bytes
}
def setSeedBytes(bytes: Array[Byte]): MersenneTwister64 = {
val mt = mt0.clone()
val bs = if (bytes.length < BYTES) Arrays.copyOf(bytes, BYTES) else bytes
val bb = ByteBuffer.wrap(bs)
var i = 0
while(i < N){
mt(i) = bb.getLong()
i += 1
}
val mti = bb.getInt
new MersenneTwister64(mt, mti)
}
// TODO improve
def reseed(n: Long) = next
def nextLong: (MersenneTwister64, Long) = {
var mti = mti0
var x = 0L
val mt1 = if (mti >= N) {
val mt = mt0.clone()
var kk = 0
while (kk < N_M) {
x = (mt(kk) & UpperMask) | (mt(kk + 1) & LowerMask)
mt(kk) = mt(kk + M) ^ (x >>> 1) ^ mag01(x)
kk += 1
}
while (kk < N_1) {
x = (mt(kk) & UpperMask) | (mt(kk + 1) & LowerMask)
mt(kk) = mt(kk + M_N) ^ (x >>> 1) ^ mag01(x)
kk += 1
}
x = (mt(N_1) & UpperMask) | (mt(0) & LowerMask)
mt(N_1) = mt(M_1) ^ (x >>> 1) ^ mag01(x)
mti = 0
mt
} else {
mt0
}
x = mt1(mti)
mti += 1
// Tempering
x ^= (x >>> 29) & 0x5555555555555555L
x ^= (x << 17) & 0x71D67FFFEDA60000L
x ^= (x << 37) & 0xFFF7EEE000000000L
x ^= (x >>> 43)
(new MersenneTwister64(mt1, mti), x)
}
def nextInt: (MersenneTwister64, Int) = {
val (r, n) = nextLong
(r, (n >>> 32).toInt)
}
// Generates a random Double in the interval [0, 1)
def nextDouble: (MersenneTwister64, Double) = {
val x = nextInt
val a: Long = (x._2.toLong & 0xffffffffL) >>> 5
val y = x._1.nextInt
val b: Long = (y._2.toLong & 0xffffffffL) >>> 6
val r = (a * 67108864.0 + b) / 9007199254740992.0
(y._1, r)
}
override def toString: String = {
mt0.mkString("MersenneTwister64(Array(", ",", s"), ${mti0})")
}
}
object MersenneTwister64 {
private final val UpperMask = 0xFFFFFFFF80000000L // = 0xFFFFFFFFFFFFFFFFL ^ Int.MinValue
private final val LowerMask = 0x7FFFFFFFL // = Int.MinValue
private final val N = 312
private final val M = 156
private final val N_M = N - M
private final val N_1 = N - 1
private final val M_N = M - N
private final val M_1 = M - 1
private final val BYTES = N * 8 + 4
@inline private def mag01(x: Long) =
if ((x & 1) == 0) 0L else 0xB5026F5AA96619EL
def standard(seed: Long): MersenneTwister64 =
new MersenneTwister64(seedFromLong(N, seed))
def fromSeed(seed: Long): MersenneTwister64 =
fromSeedArray(seedFromLong(N, seed), N + 1)
def fromArray(arr: Array[Long]): MersenneTwister64 =
fromSeedArray(seedFromArray(N, arr), N + 1)
def fromSeedArray(mt: Array[Long], mti: Int): MersenneTwister64 = {
assert(mt.length == N)
new MersenneTwister64(mt, mti)
}
def fromBytes(bytes: Array[Byte]): MersenneTwister64 =
fromArray(longsFromBytes(bytes, bytes.length / 8))
def seedFromInt(length: Int, seed: Int): Array[Int] = {
val a = new Array[Int](length)
a(0) = seed
var i = 1
while(i < length){
val x = a(i - 1)
a(i) = 1812433253 * (x ^ (x >>> 30)) + i
i += 1
}
a
}
private def seedFromLong(length: Int, seed: Long): Array[Long] = {
val a = new Array[Long](length)
a(0) = seed
var i = 1
while(i < length){
val x = a(i - 1)
a(i) = 6364136223846793005L * (x ^ (x >>> 62)) + i
i += 1
}
a
}
private def seedFromArray(length: Int, seed: Array[Long]): Array[Long] = {
val a = seedFromLong(length, 19650218)
val length_1 = length - 1
var i = 1
var j = 0
var k = java.lang.Math.max(length, seed.length)
while (k != 0) {
val x = a(i - 1)
a(i) = a(i) ^ ((x ^ (x >>> 62)) * 3935559000370003845L) + seed(j) + j
i += 1
j += 1
if (i >= length) {
a(0) = a(length_1)
i = 1
}
if (j >= seed.length) {
j = 0
}
k -= 1
}
k = length - 1
while (k != 0) {
val x = a(i - 1)
a(i) = a(i) ^ ((x ^ (x >>> 62)) * 2862933555777941757L) - i
i += 1
if (i >= length) {
a(0) = a(length_1)
i = 1
}
k -= 1
}
a(0) = 1L << 63
a
}
private[this] def longFromByteBuffer(bb: ByteBuffer): Long =
if (bb.remaining >= 8) {
bb.getLong()
} else {
var n = 0L
while (bb.remaining > 0) n = (n << 8) | bb.get
n
}
private def longsFromBytes(bytes: Array[Byte], n: Int): Array[Long] =
longsFromByteBuffer(ByteBuffer.wrap(bytes), n)
private[this] def longsFromByteBuffer(bb: ByteBuffer, n: Int): Array[Long] = {
val out = new Array[Long](n)
var i = 0
while (i < n && bb.remaining >= 8) {
out(i) = bb.getLong()
i += 1
}
if (i < n && bb.remaining > 0) out(i) = longFromByteBuffer(bb)
out
}
}
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