// prng4.js - uses arcfour as a prng

function arcfour() {
  this.i = 0;
  this.j = 0;
  this.s = new array();
}

// initialize arcfour context from key, an array of ints, each from [0..255]
function arc4init(key) {
  var i, j, t;
  for(i = 0; i < 256; ++i)
    this.s[i] = i;
  j = 0;
  for(i = 0; i < 256; ++i) {
    j = (j + this.s[i] + key[i % key.length]) & 255;
    t = this.s[i];
    this.s[i] = this.s[j];
    this.s[j] = t;
  }
  this.i = 0;
  this.j = 0;
}

function arc4next() {
  var t;
  this.i = (this.i + 1) & 255;
  this.j = (this.j + this.s[this.i]) & 255;
  t = this.s[this.i];
  this.s[this.i] = this.s[this.j];
  this.s[this.j] = t;
  return this.s[(t + this.s[this.i]) & 255];
}

arcfour.prototype.init = arc4init;
arcfour.prototype.next = arc4next;

// plug in your rng constructor here
function prng_newstate() {
  return new arcfour();
}

// pool size must be a multiple of 4 and greater than 32.
// an array of bytes the size of the pool will be passed to init()
var rng_psize = 256;