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Simple Javascript implementation of CMWC Psuedorandom algorithm
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// This was basically ripped straight from http://en.wikipedia.org/wiki/Multiply-with-carry, just javscriptified. | |
var CMWCRand = function(seed) { | |
var i, PHI = 0x9e3779b9; | |
if(!seed) { seed = Date.now(); } | |
var Q = this.Q = new Uint32Array(4096); | |
this.c = 362436; | |
this.i = 4095; | |
Q[0] = seed; | |
Q[1] = seed + PHI; | |
Q[2] = seed + PHI + PHI; | |
for(i = 3; i < 4096; ++i) { | |
Q[i] = Q[i - 3] ^ Q[i - 2] ^ PHI ^ i; | |
} | |
}; | |
CMWCRand.prototype.randomUInt32 = function() { | |
var Q = this.Q; | |
var t, a = 18782; | |
var x, r = 0xfffffffe; | |
this.i = (this.i + 1) & 4095; | |
t = a * Q[this.i] + this.c; | |
this.c = (t >> 32); | |
x = t + this.c; | |
if (x < this.c) { | |
x++; | |
this.c++; | |
} | |
return (Q[this.i] = r - x); | |
}; | |
var randRange = 1.0/0xffffffff; | |
CMWCRand.prototype.random = function() { | |
return this.randomUInt32() * randRange; | |
}; |
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