feat:node-modules

node_modules/seedrandom/lib/tychei.js

@@ -0,0 +1,103 @@
+// A Javascript implementaion of the "Tyche-i" prng algorithm by
+// Samuel Neves and Filipe Araujo.
+// See https://eden.dei.uc.pt/~sneves/pubs/2011-snfa2.pdf
+
+(function(global, module, define) {
+
+function XorGen(seed) {
+  var me = this, strseed = '';
+
+  // Set up generator function.
+  me.next = function() {
+    var b = me.b, c = me.c, d = me.d, a = me.a;
+    b = (b << 25) ^ (b >>> 7) ^ c;
+    c = (c - d) | 0;
+    d = (d << 24) ^ (d >>> 8) ^ a;
+    a = (a - b) | 0;
+    me.b = b = (b << 20) ^ (b >>> 12) ^ c;
+    me.c = c = (c - d) | 0;
+    me.d = (d << 16) ^ (c >>> 16) ^ a;
+    return me.a = (a - b) | 0;
+  };
+
+  /* The following is non-inverted tyche, which has better internal
+   * bit diffusion, but which is about 25% slower than tyche-i in JS.
+  me.next = function() {
+    var a = me.a, b = me.b, c = me.c, d = me.d;
+    a = (me.a + me.b | 0) >>> 0;
+    d = me.d ^ a; d = d << 16 ^ d >>> 16;
+    c = me.c + d | 0;
+    b = me.b ^ c; b = b << 12 ^ d >>> 20;
+    me.a = a = a + b | 0;
+    d = d ^ a; me.d = d = d << 8 ^ d >>> 24;
+    me.c = c = c + d | 0;
+    b = b ^ c;
+    return me.b = (b << 7 ^ b >>> 25);
+  }
+  */
+
+  me.a = 0;
+  me.b = 0;
+  me.c = 2654435769 | 0;
+  me.d = 1367130551;
+
+  if (seed === Math.floor(seed)) {
+    // Integer seed.
+    me.a = (seed / 0x100000000) | 0;
+    me.b = seed | 0;
+  } else {
+    // String seed.
+    strseed += seed;
+  }
+
+  // Mix in string seed, then discard an initial batch of 64 values.
+  for (var k = 0; k < strseed.length + 20; k++) {
+    me.b ^= strseed.charCodeAt(k) | 0;
+    me.next();
+  }
+}
+
+function copy(f, t) {
+  t.a = f.a;
+  t.b = f.b;
+  t.c = f.c;
+  t.d = f.d;
+  return t;
+};
+
+function impl(seed, opts) {
+  var xg = new XorGen(seed),
+      state = opts && opts.state,
+      prng = function() { return (xg.next() >>> 0) / 0x100000000; };
+  prng.double = function() {
+    do {
+      var top = xg.next() >>> 11,
+          bot = (xg.next() >>> 0) / 0x100000000,
+          result = (top + bot) / (1 << 21);
+    } while (result === 0);
+    return result;
+  };
+  prng.int32 = xg.next;
+  prng.quick = prng;
+  if (state) {
+    if (typeof(state) == 'object') copy(state, xg);
+    prng.state = function() { return copy(xg, {}); }
+  }
+  return prng;
+}
+
+if (module && module.exports) {
+  module.exports = impl;
+} else if (define && define.amd) {
+  define(function() { return impl; });
+} else {
+  this.tychei = impl;
+}
+
+})(
+  this,
+  (typeof module) == 'object' && module,    // present in node.js
+  (typeof define) == 'function' && define   // present with an AMD loader
+);
+
+