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Snack-X/pcg.js

Created January 29, 2015 07:40
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pcg32 in javascript, see http://www.pcg-random.org/
Raw
pcg.js
var pcg32 = require("./pcg32");
// make a generator
// must seed
var rng = pcg32.rng();
pcg32.srandom_r(rng, 42, 52);
for(var i = 0 ; i < 16 ; i++)
console.log(pcg32.random_r(rng));
// or use it global
// must seed
pcg32.srandom(42, 52);
for(var i = 0 ; i < 16 ; i++)
console.log(pcg32.random());
Raw
pcg32.js
var UINT64 = function(a, b, c, d) {
var a48, a32, a16, a00;
var _mask = {
1: 0x0001,
2: 0x0003,
3: 0x0007,
4: 0x000f,
5: 0x001f,
6: 0x003f,
7: 0x007f,
8: 0x00ff,
9: 0x01ff,
10: 0x03ff,
11: 0x07ff,
12: 0x0fff,
13: 0x1fff,
14: 0x3fff,
15: 0x7fff,
16: 0xffff,
32: 0xffffffff
};
if(typeof c === "undefined") {
a48 = (a >> 16) & _mask[16];
a32 = a & _mask[16];
a16 = (b >> 16) & _mask[16];
a00 = b & _mask[16];
}
else {
a48 = a;
a32 = b;
a16 = c;
a00 = d;
}
function rshift(n) {
n = +n;
if(n <= 0) return UINT64(a48, a32, a16, a00);
if(n >= 64) return UINT64(0, 0, 0, 0);
if(n === 16) return UINT64(0, a48, a32, a16);
if(n === 32) return UINT64(0, 0, a48, a32);
if(n === 48) return UINT64(0, 0, 0, a48);
var _n = n % 16;
var a = a48 >> _n;
var b = ((a48 & _mask[_n]) << (16 - _n)) | (a32 >> _n);
var c = ((a32 & _mask[_n]) << (16 - _n)) | (a16 >> _n);
var d = ((a16 & _mask[_n]) << (16 - _n)) | (a00 >> _n);
a = a & _mask[16];
b = b & _mask[16];
c = c & _mask[16];
d = d & _mask[16];
if(n < 16) return UINT64(a, b, c, d);
else if(n < 32) return UINT64(0, a, b, c);
else if(n < 48) return UINT64(0, 0, a, b);
else return UINT64(0, 0, 0, a);
}
function lshift(n) {
n = +n;
if(n <= 0) return UINT64(a48, a32, a16, a00);
if(n >= 64) return UINT64(0, 0, 0, 0);
if(n === 16) return UINT64(a32, a16, a00, 0);
if(n === 32) return UINT64(a16, a00, 0, 0);
if(n === 48) return UINT64(a00, 0, 0, 0);
var _n = n % 16;
var a = (a48 << _n) | (a32 >> (16 - _n));
var b = (a32 << _n) | (a16 >> (16 - _n));
var c = (a16 << _n) | (a00 >> (16 - _n));
var d = a00 << _n;
a = a & _mask[16];
b = b & _mask[16];
c = c & _mask[16];
d = d & _mask[16];
if(n < 16) return UINT64(a, b, c, d);
else if(n < 32) return UINT64(b, c, d, 0);
else if(n < 48) return UINT64(c, d, 0, 0);
else return UINT64(d, 0, 0, 0);
}
function or(other) {
return UINT64(
a48 | other._a48,
a32 | other._a32,
a16 | other._a16,
a00 | other._a00
);
}
function xor(other) {
return UINT64(
a48 ^ other._a48,
a32 ^ other._a32,
a16 ^ other._a16,
a00 ^ other._a00
);
}
function and(other) {
return UINT64(
a48 & other._a48,
a32 & other._a32,
a16 & other._a16,
a00 & other._a00
);
}
function mul(other) {
var b00 = other._a00;
var b16 = other._a16;
var b32 = other._a32;
var b48 = other._a48;
var c00 = a00 * b00
var c16 = c00 >> 16;
c16 += a00 * b16;
var c32 = c16 >> 16;
c16 &= _mask[16];
c16 += a16 * b00;
c32 += c16 >> 16;
c32 += a00 * b32;
var c48 = c32 >> 16;
c32 &= _mask[16];
c32 += a16 * b16;
c48 += c32 >> 16;
c32 &= _mask[16];
c32 += a32 * b00;
c48 += c32 >> 16;
c48 += a00 * b48;
c48 &= _mask[16];
c48 += a16 * b32;
c48 &= _mask[16];
c48 += a32 * b16;
c48 &= _mask[16];
c48 += a48 * b00;
c00 = c00 & _mask[16];
c16 = c16 & _mask[16];
c32 = c32 & _mask[16];
c48 = c48 & _mask[16];
return UINT64(c48, c32, c16, c00);
}
function add(other) {
var b00 = other._a00;
var b16 = other._a16;
var b32 = other._a32;
var b48 = other._a48;
var c00 = a00 + b00;
var c16 = a16 + b16 + (c00 >> 16);
var c32 = a32 + b32 + (c16 >> 16);
var c48 = a48 + b48 + (c32 >> 16);
c00 = c00 & _mask[16];
c16 = c16 & _mask[16];
c32 = c32 & _mask[16];
c48 = c48 & _mask[16];
return UINT64(c48, c32, c16, c00);
}
function hex() {
if(a48 === 0 && a32 === 0 && a16 === 0 && a00 === 0) return "0";
var o = a00.toString(16);
while(o.length < 4) o = "0" + o;
o = a16.toString(16) + o;
while(o.length < 8) o = "0" + o;
o = a32.toString(16) + o;
while(o.length < 12) o = "0" + o;
o = a48.toString(16) + o;
while(o.length < 16) o = "0" + o;
o = o.replace(/^0+/, "");
return "0x" + o;
}
function bin() {
if(a48 === 0 && a32 === 0 && a16 === 0 && a00 === 0) return "0";
var o = a00.toString(2);
while(o.length < 16) o = "0" + o;
o = a16.toString(2) + o;
while(o.length < 32) o = "0" + o;
o = a32.toString(2) + o;
while(o.length < 48) o = "0" + o;
o = a48.toString(2) + o;
while(o.length < 64) o = "0" + o;
o = o.replace(/^0+/, "");
return "0b" + o;
}
return {
_a48: a48,
_a32: a32,
_a16: a16,
_a00: a00,
rshift: rshift,
lshift: lshift,
or: or,
xor: xor,
and: and,
mul: mul,
add: add,
hex: hex,
bin: bin
};
};
var rng = function(state, inc) {
var state = state | 0;
var inc = inc | 0;
return {
state: state,
inc: inc
};
};
var _pcg32_global = rng(UINT64(0x853c49e6, 0x748fea9b), UINT64(0xda3e39cb, 0x94b95bdb));
function srandom_r(_rng, initstate, initseq) {
if(typeof initstate === "number") initstate = UINT64(Math.floor(initstate / 0xffffffff), initstate >> 32);
if(typeof initseq === "number") initseq = UINT64(Math.floor(initseq / 0xffffffff), initseq >> 32);
_rng.state = UINT64(0, 0);
_rng.inc = initseq.lshift(1).or(UINT64(0, 1));
random_r(_rng);
_rng.state = _rng.state.add(initstate);
random_r(_rng);
}
function srandom(seed, seq) {
srandom_r(_pcg32_global, seed, seq);
}
function random_r(_rng) {
var oldstate = _rng.state;
_rng.state = oldstate.mul(UINT64(0x5851f42d, 0x4c957f2d)).add(_rng.inc);
var xorshifted = oldstate.rshift(18).xor(oldstate).rshift(27).and(UINT64(0, 0xffffffff));
var rot = oldstate.rshift(59)._a00;
var rot2 = (-rot) & 31;
var result = xorshifted.rshift(rot).or(xorshifted.lshift(rot2)).and(UINT64(0, 0xffffffff));
var result32 = parseInt(result.hex(), 16);
return result32;
}
function random() {
return random_r(_pcg32_global);
}
var _export = {
UINT64: UINT64,
rng: rng,
srandom_r: srandom_r,
srandom: srandom,
random_r: random_r,
random: random
};
if(typeof module !== "undefined" && typeof module.exports !== "undefined")
module.exports = _export;
if(typeof window !== "undefined")
window.pcg32 = _export;
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