**** Merged from MCS ****
[mono-project.git] / mcs / class / corlib / System / Random.cs
blobe730865d76ec504dbcd1a7cc99ed56e95e9557ad
1 //
2 // System.Random.cs
3 //
4 // Authors:
5 // Bob Smith (bob@thestuff.net)
6 // Ben Maurer (bmaurer@users.sourceforge.net)
7 //
8 // (C) 2001 Bob Smith. http://www.thestuff.net
9 // (C) 2003 Ben Maurer
13 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
15 // Permission is hereby granted, free of charge, to any person obtaining
16 // a copy of this software and associated documentation files (the
17 // "Software"), to deal in the Software without restriction, including
18 // without limitation the rights to use, copy, modify, merge, publish,
19 // distribute, sublicense, and/or sell copies of the Software, and to
20 // permit persons to whom the Software is furnished to do so, subject to
21 // the following conditions:
22 //
23 // The above copyright notice and this permission notice shall be
24 // included in all copies or substantial portions of the Software.
25 //
26 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
27 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
28 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
29 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
30 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
31 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
32 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
35 namespace System
37 [Serializable]
38 public class Random
40 const int MBIG = int.MaxValue;
41 const int MSEED = 161803398;
42 const int MZ = 0;
44 int inext, inextp;
45 int [] SeedArray = new int [56];
47 public Random ()
48 : this (Environment.TickCount)
52 public Random (int Seed)
54 int ii;
55 int mj, mk;
57 // Numerical Recipes in C online @ http://www.library.cornell.edu/nr/bookcpdf/c7-1.pdf
58 mj = MSEED - Math.Abs (Seed);
59 SeedArray [55] = mj;
60 mk = 1;
61 for (int i = 1; i < 55; i++) { // [1, 55] is special (Knuth)
62 ii = (21 * i) % 55;
63 SeedArray [ii] = mk;
64 mk = mj - mk;
65 if (mk < 0)
66 mk += MBIG;
67 mj = SeedArray [ii];
69 for (int k = 1; k < 5; k++) {
70 for (int i = 1; i < 56; i++) {
71 SeedArray [i] -= SeedArray [1 + (i + 30) % 55];
72 if (SeedArray [i] < 0)
73 SeedArray [i] += MBIG;
76 inext = 0;
77 inextp = 31;
80 protected virtual double Sample ()
82 int retVal;
84 if (++inext >= 56) inext = 1;
85 if (++inextp >= 56) inextp = 1;
87 retVal = SeedArray [inext] - SeedArray [inextp];
89 if (retVal < 0)
90 retVal += MBIG;
92 SeedArray [inext] = retVal;
94 return retVal * (1.0 / MBIG);
97 public virtual int Next ()
99 return (int)(Sample () * int.MaxValue);
102 public virtual int Next (int maxValue)
104 if (maxValue < 0)
105 throw new ArgumentOutOfRangeException(Locale.GetText (
106 "Max value is less then min value."));
108 return (int)(Sample () * maxValue);
111 public virtual int Next (int minValue, int maxValue)
113 if (minValue > maxValue)
114 throw new ArgumentOutOfRangeException (Locale.GetText (
115 "Min value is greater then max value."));
117 uint diff = (uint)(maxValue - minValue);
118 if (diff == 0)
119 return minValue;
121 int result = (int)(Sample () * diff + minValue);
122 return ((result != maxValue) ? result : (result - 1));
125 public virtual void NextBytes (byte [] buffer)
127 if (buffer == null)
128 throw new ArgumentNullException ("buffer");
130 for (int i = 0; i < buffer.Length; i++) {
131 buffer [i] = (byte)(Sample () * (byte.MaxValue + 1));
135 public virtual double NextDouble ()
137 return this.Sample ();