@aresrpg/aresrpg-sdk/src/utils/alea.js

General SDK to interract with AresRPG

/* eslint-disable @typescript-eslint/naming-convention */
// From http://baagoe.com/en/RandomMusings/javascript/

function Mash() {
  let n = 0xefc8249d

  const mash = data => {
    const str = String(data)
    for (let i = 0; i < str.length; i++) {
      n += str.charCodeAt(i)
      let h = 0.02519603282416938 * n
      n = h >>> 0
      h -= n
      h *= n
      n = h >>> 0
      h -= n
      n += h * 0x100000000 // 2^32
    }
    return (n >>> 0) * 2.3283064365386963e-10 // 2^-32
  }

  mash.version = 'Mash 0.9'
  return mash
}

export default function Alea(...args) {
  let s0 = 0
  let s1 = 0
  let s2 = 0
  let c = 1

  if (args.length === 0) {
    args = [+new Date()]
  }

  let mash = Mash()
  s0 = mash(' ')
  s1 = mash(' ')
  s2 = mash(' ')

  for (let i = 0; i < args.length; i++) {
    s0 -= mash(args[i])
    if (s0 < 0) s0 += 1
    s1 -= mash(args[i])
    if (s1 < 0) s1 += 1
    s2 -= mash(args[i])
    if (s2 < 0) s2 += 1
  }
  mash = null

  const random = function () {
    const t = 2091639 * s0 + c * 2.3283064365386963e-10 // 2^-32
    s0 = s1
    s1 = s2
    return (s2 = t - (c = t | 0))
  }

  random.next = random
  random.uint32 = () => random() * 0x100000000 // 2^32
  random.fract53 = () =>
    random() + ((random() * 0x200000) | 0) * 1.1102230246251565e-16 // 2^-53
  random.version = 'Alea 0.9'
  random.args = args

  random.exportState = () => [s0, s1, s2, c]
  random.importState = state => {
    s0 = +state[0] || 0
    s1 = +state[1] || 0
    s2 = +state[2] || 0
    c = +state[3] || 0
  }

  return random
}