1 files changed, 45 insertions, 0 deletions
diff --git a/javascript/prng4.js b/javascript/prng4.js
new file mode 100644
index 0000000..3034f3f
--- /dev/null
+++ b/javascript/prng4.js
@@ -0,0 +1,45 @@
+// 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;