Kotlin Random

Random.kt

import kotlin.math.floor

/**
 * This class implement a Linear Congruential Generator.
 *
 * @author Valentin Michalak
 */
class Random(private var seed: Long = 0) {

    companion object {
        private val mask:       Long = (1L shl 48) - 1
        private val multiplier: Long = 25214903917
        private val increment:  Long = 11
    }

    /**
     * @param bitCount (Max 48)
     */
    private fun next(bitCount: Int): Int {
        seed = (multiplier * seed + increment) and mask
        return seed.ushr(48 - bitCount).toInt()
    }

    fun nextBoolean(): Boolean = next(1) != 0
    fun nextDouble(): Double = ((next(26).toLong() shl 27) + next(27)) / (1L shl 53).toDouble()
    fun nextFloat(): Float = next(24) / (1 shl 24).toFloat()
    fun nextInt(): Int = next(32)
    fun nextInt(range: IntRange): Int = floor(nextDouble() * (1 + range.last - range.first)).toInt() + range.first
    fun nextLong(): Long = (next(32).toLong() shl 32) + next(32)
}