feat:node-modules

node_modules/seedrandom/lib/xorshift7.js

@@ -0,0 +1,97 @@
+// A Javascript implementaion of the "xorshift7" algorithm by
+// François Panneton and Pierre L'ecuyer:
+// "On the Xorgshift Random Number Generators"
+// http://saluc.engr.uconn.edu/refs/crypto/rng/panneton05onthexorshift.pdf
+
+(function(global, module, define) {
+
+function XorGen(seed) {
+  var me = this;
+
+  // Set up generator function.
+  me.next = function() {
+    // Update xor generator.
+    var X = me.x, i = me.i, t, v, w;
+    t = X[i]; t ^= (t >>> 7); v = t ^ (t << 24);
+    t = X[(i + 1) & 7]; v ^= t ^ (t >>> 10);
+    t = X[(i + 3) & 7]; v ^= t ^ (t >>> 3);
+    t = X[(i + 4) & 7]; v ^= t ^ (t << 7);
+    t = X[(i + 7) & 7]; t = t ^ (t << 13); v ^= t ^ (t << 9);
+    X[i] = v;
+    me.i = (i + 1) & 7;
+    return v;
+  };
+
+  function init(me, seed) {
+    var j, w, X = [];
+
+    if (seed === (seed | 0)) {
+      // Seed state array using a 32-bit integer.
+      w = X[0] = seed;
+    } else {
+      // Seed state using a string.
+      seed = '' + seed;
+      for (j = 0; j < seed.length; ++j) {
+        X[j & 7] = (X[j & 7] << 15) ^
+            (seed.charCodeAt(j) + X[(j + 1) & 7] << 13);
+      }
+    }
+    // Enforce an array length of 8, not all zeroes.
+    while (X.length < 8) X.push(0);
+    for (j = 0; j < 8 && X[j] === 0; ++j);
+    if (j == 8) w = X[7] = -1; else w = X[j];
+
+    me.x = X;
+    me.i = 0;
+
+    // Discard an initial 256 values.
+    for (j = 256; j > 0; --j) {
+      me.next();
+    }
+  }
+
+  init(me, seed);
+}
+
+function copy(f, t) {
+  t.x = f.x.slice();
+  t.i = f.i;
+  return t;
+}
+
+function impl(seed, opts) {
+  if (seed == null) seed = +(new Date);
+  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 (state.x) 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.xorshift7 = impl;
+}
+
+})(
+  this,
+  (typeof module) == 'object' && module,    // present in node.js
+  (typeof define) == 'function' && define   // present with an AMD loader
+);
+