DBot/kommons
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Provide PCG XSH RR random implementation

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This commit is contained in:
DBotThePony 2025-03-08 17:12:13 +07:00
parent ed8a5edcda
commit 7d00896b46
Signed by: DBot
GPG Key ID: DCC23B5715498507
4 changed files with 43 additions and 5 deletions
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2
gradle.properties
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@ -4,7 +4,7 @@ kotlin.code.style=official
specifyKotlinAsDependency=false
projectGroup=ru.dbotthepony.kommons
projectVersion=3.2.1
projectVersion=3.3.0
guavaDepVersion=33.0.0
gsonDepVersion=2.8.9

28
src/main/kotlin/ru/dbotthepony/kommons/random/PCG32Random.kt Normal file
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@ -0,0 +1,28 @@
package ru.dbotthepony.kommons.random
import java.util.random.RandomGenerator
/**
* PCG XSH RR 32-bit (64-bit state) random generator, which has better statistical properties
* than plain [LCG64Random] generator
*/
open class PCG32Random(protected var seed: Long) : RandomGenerator {
final override fun nextInt(): Int {
var x = this.seed
this.seed = LCG64Random.MULTIPLIER * this.seed + LCG64Random.INCREMENT
val rot = x.ushr(59) and MASK
x = x.xor(x.ushr(18))
return x.ushr(27).toInt().rotateLeft(rot.toInt())
}
override fun nextLong(): Long {
val a = nextInt().toLong()
val b = nextInt().toLong() and 0xFFFFFFFFL
return a.shl(32) or b
}
companion object {
const val MASK = (1L shl 5) - 1L
}
}

9
src/main/kotlin/ru/dbotthepony/kommons/random/Xoshiro256PlusPlusRandom.kt
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@ -2,6 +2,11 @@ package ru.dbotthepony.kommons.random
import java.util.random.RandomGenerator
/**
* Excellent PRNG with expected period of 2^255 - 1, a slightly faster version than [Xoshiro256StarStarRandom].
*
* Where [Xoshiro256PlusPlusRandom] is used consider using [Xoshiro256StarStarRandom] instead.
*/
open class Xoshiro256PlusPlusRandom protected constructor(
protected var s0: Long,
protected var s1: Long,
@ -25,14 +30,14 @@ open class Xoshiro256PlusPlusRandom protected constructor(
}
constructor(seed: Long) : this(1L, 0L, 0L, 0L, null) {
val rng = LCG64Random(seed)
val rng = PCG32Random(seed)
s0 = rng.nextLong()
s1 = rng.nextLong()
s2 = rng.nextLong()
s3 = rng.nextLong()
}
override fun nextLong(): Long {
final override fun nextLong(): Long {
val result = (s0 + s3).rotateLeft(23) + s1
val t = s1.shl(17)
s2 = s2.xor(s0)

9
src/main/kotlin/ru/dbotthepony/kommons/random/Xoshiro256StarStarRandom.kt
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@ -2,6 +2,11 @@ package ru.dbotthepony.kommons.random
import java.util.random.RandomGenerator
/**
* Excellent PRNG with expected period of 2^255 - 1, which is de-facto standard PRNG
* used in many applications and programming languages (where not restricted
* by backward compatibility)
*/
open class Xoshiro256StarStarRandom protected constructor(
protected var s0: Long,
protected var s1: Long,
@ -25,14 +30,14 @@ open class Xoshiro256StarStarRandom protected constructor(
}
constructor(seed: Long) : this(1L, 0L, 0L, 0L, null) {
val rng = LCG64Random(seed)
val rng = PCG32Random(seed)
s0 = rng.nextLong()
s1 = rng.nextLong()
s2 = rng.nextLong()
s3 = rng.nextLong()
}
override fun nextLong(): Long {
final override fun nextLong(): Long {
val result = (s1 * 5).rotateLeft(7) * 9
val t = s1.shl(17)
s2 = s2.xor(s0)