/js/lib/Socket.IO-node/support/socket.io-client/lib/vendor/web-socket-js/flash-src/com/hurlant/math/BarrettReduction.as

 1package com.hurlant.math
 2{
 3	use namespace bi_internal;
 4
 5	internal class BarrettReduction implements IReduction
 6	{
 7		private var m:BigInteger;
 8		private var r2:BigInteger;
 9		private var q3:BigInteger;
10		private var mu:BigInteger;
11		
12		public function BarrettReduction(m:BigInteger) {
13			// setup Barrett
14			r2 = new BigInteger;
15			q3 = new BigInteger;
16			BigInteger.ONE.dlShiftTo(2*m.t, r2);
17			mu = r2.divide(m);
18			this.m = m;
19		}
20		
21		public function revert(x:BigInteger):BigInteger
22		{
23			return x;
24		}
25		
26		/**
27		 * 
28		 * @param x
29		 * @param y
30		 * @param r = x*y mod m; x != r
31		 * 
32		 */
33		public function mulTo(x:BigInteger, y:BigInteger, r:BigInteger):void
34		{
35			x.multiplyTo(y, r);
36			reduce(r);
37		}
38		
39		/**
40		 * 
41		 * @param x
42		 * @param r = x^2 mod m; x != r
43		 * 
44		 */
45		public function sqrTo(x:BigInteger, r:BigInteger):void
46		{
47			x.squareTo(r);
48			reduce(r);
49		}
50		
51		public function convert(x:BigInteger):BigInteger
52		{
53			if (x.s<0 || x.t>2*m.t) {
54				return x.mod(m);
55			} else if (x.compareTo(m)<0) {
56				return x;
57			} else {
58				var r:BigInteger = new BigInteger;
59				x.copyTo(r);
60				reduce(r);
61				return r;
62			}
63		}
64		
65		/**
66		 * 
67		 * @param x = x mod m (HAC 14.42)
68		 * 
69		 */
70		public function reduce(lx:BigInteger):void
71		{
72			var x:BigInteger = lx as BigInteger;
73			x.drShiftTo(m.t-1,r2);
74			if (x.t>m.t+1) {
75				x.t = m.t+1;
76				x.clamp();
77			}
78			mu.multiplyUpperTo(r2, m.t+1, q3);
79			m.multiplyLowerTo(q3, m.t+1, r2);
80			while (x.compareTo(r2)<0) {
81				x.dAddOffset(1, m.t+1);
82			}
83			x.subTo(r2,x);
84			while (x.compareTo(m)>=0) {
85				x.subTo(m,x);
86			}
87		}
88		
89	}
90}