mRandom.h

  1
  2//-----------------------------------------------------------------------------
  3// Copyright (c) 2012 GarageGames, LLC
  4//
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  6// of this software and associated documentation files (the "Software"), to
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  9// sell copies of the Software, and to permit persons to whom the Software is
 10// furnished to do so, subject to the following conditions:
 11//
 12// The above copyright notice and this permission notice shall be included in
 13// all copies or substantial portions of the Software.
 14//
 15// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 16// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 17// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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 21// IN THE SOFTWARE.
 22//-----------------------------------------------------------------------------
 23
 24#ifndef _MRANDOM_H_
 25#define _MRANDOM_H_
 26
 27#ifndef _PLATFORMASSERT_H_
 28#include "platform/platformAssert.h"
 29#endif
 30
 31
 32//--------------------------------------
 33/// Base class for random number generators
 34class MRandomGenerator
 35{
 36protected:
 37   MRandomGenerator() :mSeed(-1) {}
 38   S32  mSeed;
 39
 40public:
 41   virtual ~MRandomGenerator() {}
 42   
 43   void setSeed();
 44   S32  getSeed() { return mSeed; }
 45   virtual void setSeed(S32 s) = 0;
 46
 47   virtual U32 randI( void ) = 0;      ///< 0..2^31 random number generator
 48   virtual F32  randF( void );         ///< 0.0 .. 1.0 F32 random number generator
 49   S32 randI(S32 i, S32 n);            ///< i..n integer random number generator
 50   F32 randF(F32 i, F32 n);            ///< i..n F32 random number generator
 51};
 52
 53
 54//--------------------------------------
 55inline F32 MRandomGenerator::randF()
 56{
 57   // default: multiply by 1/(2^31)
 58   return F32(randI()) * (1.0f / S32_MAX);
 59}
 60
 61inline S32 MRandomGenerator::randI(S32 i, S32 n)
 62{
 63   AssertFatal(i<=<a href="/coding/file/cmdscan_8cpp/#cmdscan_8cpp_1aeab71244afb687f16d8c4f5ee9d6ef0e">n</a>, "MRandomGenerator::randi: inverted range.");
 64   return (S32)(i + (randI() % (n - i + 1)) );
 65}
 66
 67inline F32 MRandomGenerator::randF(F32 i, F32 n)
 68{
 69   AssertFatal(i<=<a href="/coding/file/cmdscan_8cpp/#cmdscan_8cpp_1aeab71244afb687f16d8c4f5ee9d6ef0e">n</a>, "MRandomGenerator::randf: inverted range.");
 70   return (i + (n - i) * randF());
 71}
 72
 73
 74//--------------------------------------
 75/// Linear Congruential Method, the "minimal standard generator"
 76///
 77/// Fast, farly good random numbers (better than using rand)
 78///
 79/// @author Park & Miller, 1988, Comm of the ACM, 31(10), pp. 1192-1201
 80class MRandomLCG : public MRandomGenerator
 81{
 82protected:
 83   static const S32 msQuotient;
 84   static const S32 msRemainder;
 85
 86public:
 87   MRandomLCG();
 88   MRandomLCG(S32 s);
 89   virtual ~MRandomLCG() {}
 90
 91   static void setGlobalRandSeed(U32 seed);
 92
 93   void setSeed(S32 s);
 94//   using MRandomGenerator::randI;
 95    S32 randI(S32 i, S32 n);            ///< i..n integer generator
 96
 97   U32 randI( void );
 98
 99};
100
101// Solution to "using" problem.
102inline S32 MRandomLCG::randI(S32 i, S32 n)
103{
104    return( MRandomGenerator::randI(i,n) );
105}
106
107
108//--------------------------------------
109/// Fast, very good random numbers
110///
111/// Period = 2^249
112///
113/// Kirkpatrick, S., and E. Stoll, 1981; A Very Fast Shift-Register
114///       Sequence Random Number Generator, Journal of Computational Physics,
115/// V. 40.
116///
117/// Maier, W.L., 1991; A Fast Pseudo Random Number Generator,
118/// Dr. Dobb's Journal, May, pp. 152 - 157
119class MRandomR250: public MRandomGenerator
120{
121private:
122   U32 mBuffer[250];
123   S32 mIndex;
124
125public:
126   MRandomR250();
127   MRandomR250(S32 s);
128   virtual ~MRandomR250() {}
129
130   void setSeed(S32 s);
131// using MRandomGenerator::randI;
132   U32 randI();
133};
134
135
136typedef MRandomLCG MRandom;
137
138extern MRandomLCG gRandGen;
139
140
141#endif //_MRANDOM_H_
142