Initial source commit

minorGems/util/random/StdRandomSource.h

@@ -0,0 +1,152 @@
+// Jason Rohrer
+// StdRandomSource.h
+
+/**
+*
+*	Implementation of random number generation that uses stdlib calls
+*
+*
+*	Created 12-7-99
+*	Mods:
+*   	Jason Rohrer	9-28-2000	Added a getRandomBoundedInt()
+*									implementation
+*   	Jason Rohrer	12-7-2000	Overloaded constructor to support
+*									specifying a seed.
+*   	Jason Rohrer	12-16-2000	Added a getRandomDouble() function.
+*   	Jason Rohrer	12-17-2000	Fixed bug in initialization of invDMAX
+*									in default constructor.
+*   	Jason Rohrer	9-13-2001	Fixed a bug in getRandomBoundedInt()
+*									as floats were being used, and they
+*									don't provide enough resolution.
+*   	Jason Rohrer	10-11-2002	Fixed some type casting warnings.
+*   	Jason Rohrer	07-09-2006	Added getRandomBoundedDouble.
+*   	Jason Rohrer	07-27-2006	Added getRandomBoolean.
+*/
+
+#include "minorGems/common.h"
+
+
+
+#ifndef STD_RANDOM_SOURCE_INCLUDED
+#define STD_RANDOM_SOURCE_INCLUDED
+
+#include <stdlib.h>
+#include <time.h>
+#include "RandomSource.h"
+
+class StdRandomSource : public RandomSource {
+
+	public:		
+		
+		StdRandomSource();		// needed to seed stdlib generator
+		
+		// specify the seed for the stdlib generator
+		StdRandomSource( unsigned int inSeed );
+			
+			
+		// implements these functions
+		float getRandomFloat();	// in interval [0,1.0]
+		double getRandomDouble(); // in interval [0,1.0]
+		unsigned int getRandomInt();		// in interval [0,MAX]
+		unsigned int getIntMax();	// returns MAX
+        
+		int getRandomBoundedInt( int inRangeStart,
+			int inRangeEnd );	
+
+        double getRandomBoundedDouble( double inRangeStart,
+                                       double inRangeEnd );
+        char getRandomBoolean();
+
+        
+	private:
+		double mInvMAXPlusOne; //  1 / ( MAX + 1 )
+	};
+
+
+
+inline StdRandomSource::StdRandomSource() {
+	MAX = RAND_MAX;
+	srand( (unsigned)time(NULL) );
+	invMAX = (float)1.0 / ((float)MAX);
+	invDMAX = 1.0 / ((double)MAX);
+	mInvMAXPlusOne = 1.0 / ( ( (float)MAX ) + 1.0 );
+	}
+
+
+
+inline StdRandomSource::StdRandomSource( unsigned int inSeed ) {
+	MAX = RAND_MAX;
+	srand( inSeed );
+	invMAX = (float)1.0 / ((float)MAX);
+	invDMAX = 1.0 / ((double)MAX);
+	mInvMAXPlusOne = 1.0 / ( ( (double)MAX ) + 1.0 );
+	}
+	
+
+
+inline float StdRandomSource::getRandomFloat() {
+	
+	return (float)(rand()) * invMAX;
+	}
+
+
+
+inline double StdRandomSource::getRandomDouble() {
+	
+	return (double)(rand()) * invDMAX;
+	}
+
+
+
+inline unsigned int StdRandomSource::getRandomInt() {
+	
+	return rand();
+	}
+
+inline unsigned int StdRandomSource::getIntMax() {
+	
+	return MAX;
+	}
+
+inline int StdRandomSource::getRandomBoundedInt( int inRangeStart,
+	int inRangeEnd ) {
+	
+	// float in range [0,1)
+	double randFloat = (double)( rand() ) * mInvMAXPlusOne;
+
+	int onePastRange = inRangeEnd + 1;
+
+	int magnitude = (int)( randFloat * ( onePastRange - inRangeStart ) );
+	
+	return magnitude + inRangeStart;
+	}
+
+
+inline double StdRandomSource::getRandomBoundedDouble( double inRangeStart,
+	double inRangeEnd ) {
+	
+	// double in range [0,1]
+	double randDouble = getRandomDouble();
+
+	double magnitude = randDouble * ( inRangeEnd - inRangeStart );
+	
+	return magnitude + inRangeStart;
+	}
+
+
+
+inline char StdRandomSource::getRandomBoolean() {
+
+    // float in range [0,1]
+	double randFloat = getRandomFloat();
+
+    if( randFloat < 0.5 ) {
+        return true;
+        }
+    else {
+        return false;
+        }
+	}
+
+
+#endif