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// 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
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