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public/vstdlib/random.h

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+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: Random number generator
+//
+// $Workfile: $
+// $NoKeywords: $
+//===========================================================================//
+
+#ifndef VSTDLIB_RANDOM_H
+#define VSTDLIB_RANDOM_H
+
+#include "vstdlib/vstdlib.h"
+#include "tier0/basetypes.h"
+#include "tier0/threadtools.h"
+#include "tier1/interface.h"
+
+#define NTAB 32
+
+#pragma warning(push)
+#pragma warning( disable:4251 )
+
+//-----------------------------------------------------------------------------
+// A generator of uniformly distributed random numbers
+//-----------------------------------------------------------------------------
+class VSTDLIB_CLASS IUniformRandomStream
+{
+public:
+	//virtual ~IUniformRandomStream() { }
+
+	// Sets the seed of the random number generator
+	virtual void	SetSeed( int iSeed ) = 0;
+
+	// Generates random numbers
+	virtual float	RandomFloat( float flMinVal = 0.0f, float flMaxVal = 1.0f ) = 0;
+	virtual int		RandomInt( int iMinVal, int iMaxVal ) = 0;
+	virtual float	RandomFloatExp( float flMinVal = 0.0f, float flMaxVal = 1.0f, float flExponent = 1.0f ) = 0;
+};
+
+
+//-----------------------------------------------------------------------------
+// The standard generator of uniformly distributed random numbers
+//-----------------------------------------------------------------------------
+class VSTDLIB_CLASS CUniformRandomStream : public IUniformRandomStream
+{
+public:
+	CUniformRandomStream();
+
+	// Sets the seed of the random number generator
+	virtual void	SetSeed( int iSeed );
+
+	// Generates random numbers
+	virtual float	RandomFloat( float flMinVal = 0.0f, float flMaxVal = 1.0f );
+	virtual int		RandomInt( int iMinVal, int iMaxVal );
+	virtual float	RandomFloatExp( float flMinVal = 0.0f, float flMaxVal = 1.0f, float flExponent = 1.0f );
+
+private:
+	int		GenerateRandomNumber();
+
+	int m_idum;
+	int m_iy;
+	int m_iv[NTAB];
+
+	CThreadFastMutex m_mutex;
+};
+
+
+//-----------------------------------------------------------------------------
+// A generator of gaussian distributed random numbers
+//-----------------------------------------------------------------------------
+class VSTDLIB_CLASS CGaussianRandomStream
+{
+public:
+	// Passing in NULL will cause the gaussian stream to use the
+	// installed global random number generator
+	CGaussianRandomStream( IUniformRandomStream *pUniformStream = NULL );
+
+	// Attaches to a random uniform stream
+	void	AttachToStream( IUniformRandomStream *pUniformStream = NULL );
+
+	// Generates random numbers
+	float	RandomFloat( float flMean = 0.0f, float flStdDev = 1.0f );
+
+private:
+	IUniformRandomStream *m_pUniformStream;
+	bool	m_bHaveValue;
+	float	m_flRandomValue;
+
+	CThreadFastMutex m_mutex;
+};
+
+//-----------------------------------------------------------------------------
+// A couple of convenience functions to access the library's global uniform stream
+//-----------------------------------------------------------------------------
+VSTDLIB_INTERFACE void	RandomSeed( int iSeed );
+VSTDLIB_INTERFACE float	RandomFloat( float flMinVal = 0.0f, float flMaxVal = 1.0f );
+VSTDLIB_INTERFACE float	RandomFloatExp( float flMinVal = 0.0f, float flMaxVal = 1.0f, float flExponent = 1.0f );
+VSTDLIB_INTERFACE int	RandomInt( int iMinVal, int iMaxVal );
+VSTDLIB_INTERFACE float	RandomGaussianFloat( float flMean = 0.0f, float flStdDev = 1.0f );
+
+//-----------------------------------------------------------------------------
+// IUniformRandomStream interface for free functions
+//-----------------------------------------------------------------------------
+class VSTDLIB_CLASS CDefaultUniformRandomStream : public IUniformRandomStream
+{
+public:
+	virtual void	SetSeed( int iSeed ) OVERRIDE												{ RandomSeed( iSeed ); }
+	virtual float	RandomFloat( float flMinVal, float flMaxVal ) OVERRIDE						{ return ::RandomFloat( flMinVal, flMaxVal ); }
+	virtual int		RandomInt( int iMinVal, int iMaxVal ) OVERRIDE								{ return ::RandomInt( iMinVal, iMaxVal ); }
+	virtual float	RandomFloatExp( float flMinVal, float flMaxVal, float flExponent ) OVERRIDE	{ return ::RandomFloatExp( flMinVal, flMaxVal, flExponent ); }
+};
+
+//-----------------------------------------------------------------------------
+// Installs a global random number generator, which will affect the Random functions above
+//-----------------------------------------------------------------------------
+VSTDLIB_INTERFACE void	InstallUniformRandomStream( IUniformRandomStream *pStream );
+
+
+#pragma warning(pop)
+
+#endif // VSTDLIB_RANDOM_H
+
+
+