Compare homogeneity of some simple custom random generators using doodle (increase XSS !!) / published by https://github.com/dacr/code-examples-manager #7d55268b-312b-4dae-b62b-77eb2c950ebf/ae061d25052a322f20936f566660c18505c38acc

rng-basic-fast-random.sc

// summary : Compare homogeneity of some simple custom random generators using doodle (increase XSS !!)
// keywords : scala, random, rng, scalatest, doodle
// publish : gist
// authors : David Crosson
// license : Apache NON-AI License Version 2.0 (https://raw.githubusercontent.com/non-ai-licenses/non-ai-licenses/main/NON-AI-APACHE2)
// id : 7d55268b-312b-4dae-b62b-77eb2c950ebf
// created-on : 2019-09-10T21:18:05Z
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

// ---------------------
//> using scala "3.4.2"
//> using dep "org.creativescala::doodle:0.18.0"
// using java-opt -Xss2g
// ---------------------

class ScalaDefaultRandom(seed:Long = System.currentTimeMillis()) {
  final def nextInt(n:Int):Int = (scala.math.random()*n).toInt
}

class BasicFastRandom(seed: Long = System.currentTimeMillis()) {
  private var g_seed = (seed >> 16 & 0x7FFFFFFF).toInt
  final def nextBoolean = nextInt(2) != 0
  final def nextInt(n: Int) = {
    g_seed = 214013 * g_seed + 2531011
    ((g_seed >> 16) & 0x7FFF) % n
  }
}

class XORShift32(val seed: Long = System.currentTimeMillis()) {
  private var cseed = seed
  private def randomInt = {
    var x = cseed
    x ^= (x << 13)
    x ^= (x >>> 17)
    x ^= (x << 5)
    cseed = x
    x
  }
  final def nextInt(bound: Int):Int = ((randomInt & 0x7fffff) % bound).toInt
}


import doodle.image._
import doodle.image.syntax._
import doodle.java2d._
import cats.instances.list._
import doodle.core._
import doodle.image.syntax.all.TraverseImageOps
import doodle.image.syntax.all.ImageOps
import cats.effect.unsafe.implicits.global

def showRng(nextInt: Int => Int, color: Color) = {
  val circle = Image.circle(1).noFill.strokeWidth(1).strokeColor(color)
  val count = 20000
  1.to(count)
    .toList
    .map(f => circle.at(nextInt(250), nextInt(250)))
    .allOn
}

val seed = 500L
val i1 = showRng(new BasicFastRandom(seed).nextInt, Color.red)
val i2 = showRng(new ScalaDefaultRandom(seed).nextInt, Color.blue)
val i3 = showRng(new XORShift32(seed).nextInt, Color.green)

i1.beside(i2).beside(i3).draw()

scala.io.StdIn.readLine("Enter to exit...") // required when run as a script