//-----------------------------------------------------------------------------
// V12 Engine
// 
// Copyright (c) 2001 GarageGames.Com
// Portions Copyright (c) 2001 by Sierra Online, Inc.
//-----------------------------------------------------------------------------

#ifndef _MRANDOM_H_
#define _MRANDOM_H_


#ifndef _PLATFORM_H_
#include "Platform/platform.h"
#endif


//--------------------------------------
// Base class for random number generators
class MRandomGenerator
{
protected:
   MRandomGenerator() {}
   S32  mSeed;

public:
   void setSeed();
   S32  getSeed() { return mSeed; }
   virtual void setSeed(S32 s) = 0;

   virtual U32 randI( void ) = 0;            // 0..2^31
   virtual F32  randF( void );               // 0.0 .. 1.0 F32 generator
   S32 randI(S32 i, S32 n);            // i..n integer generator
   F32 randF(F32 i, F32 n);            // i..n F32 generator
};


//--------------------------------------
inline F32 MRandomGenerator::randF()
{
   // default: multiply by 1/(2^31)
   return  F32(randI()) * F32(1.0/2147483647.0);
}

inline S32 MRandomGenerator::randI(S32 i, S32 n)
{
   AssertFatal(i<=n, "MRandomGenerator::randi: inverted range.");
   return (S32)(i + (randI() % (n - i + 1)) );
}   

inline F32 MRandomGenerator::randF(F32 i, F32 n)
{
   AssertFatal(i<=n, "MRandomGenerator::randf: inverted range.");
   return (i + (n - i) * randF());   
}   


//--------------------------------------
// Linear Congruential Method, the "minimal standard generator"
// Fast, farly good random numbers (better than using rand)
// Park & Miller, 1988, Comm of the ACM, 31(10), pp. 1192-1201
class MRandomLCG : public MRandomGenerator
{
protected:
   static const S32 msQuotient;
   static const S32 msRemainder;

public:
   MRandomLCG();
   MRandomLCG(S32 s);

	static void setGlobalRandSeed(U32 seed);

   void setSeed(S32 s);
//   using MRandomGenerator::randI;
    S32 randI(S32 i, S32 n);            // i..n integer generator

   U32 randI( void );            

};

// Solution to "using" problem.
inline S32 MRandomLCG::randI(S32 i, S32 n)
{
    return( MRandomGenerator::randI(i,n) );
}   


//--------------------------------------
// Fast, very good random numbers
//
// Period = 2^249
//
// Kirkpatrick, S., and E. Stoll, 1981; A Very Fast Shift-Register
//       Sequence Random Number Generator, Journal of Computational Physics,
// V. 40.
//
// Maier, W.L., 1991; A Fast Pseudo Random Number Generator,
// Dr. Dobb's Journal, May, pp. 152 - 157

class MRandomR250: public MRandomGenerator
{
private:
   U32 mBuffer[250];
   S32 mIndex;

public:
   MRandomR250(); 
   MRandomR250(S32 s); 

   void setSeed(S32 s);
// using MRandomGenerator::randI;
   U32 randI();
};


typedef MRandomLCG MRandom;

extern MRandomLCG gRandGen;


#endif //_MRANDOM_H_