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122 lines
2.7 KiB
C++
122 lines
2.7 KiB
C++
//-----------------------------------------------------------------------------
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// V12 Engine
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//
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// Copyright (c) 2001 GarageGames.Com
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// Portions Copyright (c) 2001 by Sierra Online, Inc.
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//-----------------------------------------------------------------------------
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#ifndef _MRANDOM_H_
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#define _MRANDOM_H_
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#ifndef _PLATFORM_H_
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#include "Platform/platform.h"
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#endif
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//--------------------------------------
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// Base class for random number generators
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class MRandomGenerator
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{
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protected:
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MRandomGenerator() {}
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S32 mSeed;
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public:
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void setSeed();
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S32 getSeed() { return mSeed; }
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virtual void setSeed(S32 s) = 0;
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virtual U32 randI( void ) = 0; // 0..2^31
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virtual F32 randF( void ); // 0.0 .. 1.0 F32 generator
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S32 randI(S32 i, S32 n); // i..n integer generator
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F32 randF(F32 i, F32 n); // i..n F32 generator
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};
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//--------------------------------------
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inline F32 MRandomGenerator::randF()
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{
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// default: multiply by 1/(2^31)
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return F32(randI()) * F32(1.0/2147483647.0);
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}
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inline S32 MRandomGenerator::randI(S32 i, S32 n)
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{
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AssertFatal(i<=n, "MRandomGenerator::randi: inverted range.");
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return (S32)(i + (randI() % (n - i + 1)) );
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}
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inline F32 MRandomGenerator::randF(F32 i, F32 n)
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{
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AssertFatal(i<=n, "MRandomGenerator::randf: inverted range.");
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return (i + (n - i) * randF());
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}
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//--------------------------------------
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// Linear Congruential Method, the "minimal standard generator"
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// Fast, farly good random numbers (better than using rand)
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// Park & Miller, 1988, Comm of the ACM, 31(10), pp. 1192-1201
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class MRandomLCG : public MRandomGenerator
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{
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protected:
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static const S32 msQuotient;
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static const S32 msRemainder;
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public:
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MRandomLCG();
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MRandomLCG(S32 s);
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static void setGlobalRandSeed(U32 seed);
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void setSeed(S32 s);
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// using MRandomGenerator::randI;
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S32 randI(S32 i, S32 n); // i..n integer generator
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U32 randI( void );
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};
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// Solution to "using" problem.
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inline S32 MRandomLCG::randI(S32 i, S32 n)
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{
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return( MRandomGenerator::randI(i,n) );
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}
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//--------------------------------------
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// Fast, very good random numbers
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//
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// Period = 2^249
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//
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// Kirkpatrick, S., and E. Stoll, 1981; A Very Fast Shift-Register
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// Sequence Random Number Generator, Journal of Computational Physics,
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// V. 40.
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//
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// Maier, W.L., 1991; A Fast Pseudo Random Number Generator,
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// Dr. Dobb's Journal, May, pp. 152 - 157
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class MRandomR250: public MRandomGenerator
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{
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private:
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U32 mBuffer[250];
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S32 mIndex;
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public:
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MRandomR250();
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MRandomR250(S32 s);
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void setSeed(S32 s);
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// using MRandomGenerator::randI;
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U32 randI();
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};
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typedef MRandomLCG MRandom;
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extern MRandomLCG gRandGen;
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#endif //_MRANDOM_H_
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