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/*
* Modification History
*
* 2009-January-14 Jason Rohrer
* Created.
*
* 2009-February-5 Jason Rohrer
* Added support for restoring from saved state.
*
*/
#ifndef CUSTOM_RANDOM_SOURCE_INCLUDED
#define CUSTOM_RANDOM_SOURCE_INCLUDED
#include <stdlib.h>
#include <time.h>
#include "RandomSource.h"
/**
* Implementation of RandomSource that does not depend on platform or library.
*
* Maintains its own internal state.
*/
class CustomRandomSource : public RandomSource {
public:
// seeds itself with current time
CustomRandomSource();
// specify the seed
CustomRandomSource( unsigned int inSeed );
// save for rewind later
void saveState();
void rewindState();
// can be used to save state to disk
unsigned int getSavedState();
void restoreFromSavedState( unsigned int inSavedState );
void reseed( 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 )
unsigned int mState;
unsigned int mSavedState;
// returns next number and updates state
unsigned int genRand32();
};
inline CustomRandomSource::CustomRandomSource() {
MAX = 4294967295U;
mState = (unsigned)( time(NULL) );
invMAX = (float)1.0 / ((float)MAX);
invDMAX = 1.0 / ((double)MAX);
mInvMAXPlusOne = 1.0 / ( ( (float)MAX ) + 1.0 );
saveState();
}
inline CustomRandomSource::CustomRandomSource( unsigned int inSeed ) {
MAX = 4294967295U;
mState = inSeed;
invMAX = (float)1.0 / ((float)MAX);
invDMAX = 1.0 / ((double)MAX);
mInvMAXPlusOne = 1.0 / ( ( (double)MAX ) + 1.0 );
saveState();
}
inline void CustomRandomSource::saveState() {
mSavedState = mState;
}
inline void CustomRandomSource::rewindState() {
mState = mSavedState;
}
inline unsigned int CustomRandomSource::getSavedState() {
return mSavedState;
}
inline void CustomRandomSource::restoreFromSavedState(
unsigned int inSavedState) {
mState = inSavedState;
}
inline void CustomRandomSource::reseed( unsigned int inSeed ) {
mState = inSeed;
}
// from Cultivation/Passage's landscape.cpp
// faster as a set of macros
#define CustNum1( inSeed ) \
( ( inSeed * 0xFEA09B9DU ) + 1 )
#define CustNum2( inSeed ) \
( ( ( inSeed ^ CustNum1( inSeed ) ) * 0x9C129511U ) + 1 )
#define CustNum3( inSeed ) \
( ( inSeed * 0x2512CFB8U ) + 1 )
#define CustNum4( inSeed ) \
( ( ( inSeed ^ CustNum3( inSeed ) ) * 0xB89C8895U ) + 1 )
#define CustNum5( inSeed ) \
( ( inSeed * 0x6BF962C1U ) + 1 )
#define CustNum6( inSeed ) \
( ( ( inSeed ^ CustNum5( inSeed ) ) * 0x4BF962C1U ) + 1 )
inline unsigned int CustomRandomSource::genRand32() {
mState =
CustNum2( mState ) ^
(CustNum4( mState ) >> 11) ^
(CustNum6( mState ) >> 22);
return mState;
}
inline float CustomRandomSource::getRandomFloat() {
return (float)(genRand32()) * invMAX;
}
inline double CustomRandomSource::getRandomDouble() {
return (double)(genRand32()) * invDMAX;
}
inline unsigned int CustomRandomSource::getRandomInt() {
return genRand32();
}
inline unsigned int CustomRandomSource::getIntMax() {
return MAX;
}
inline int CustomRandomSource::getRandomBoundedInt( int inRangeStart,
int inRangeEnd ) {
// float in range [0,1)
double randFloat = (double)( genRand32() ) * mInvMAXPlusOne;
int onePastRange = inRangeEnd + 1;
int magnitude = (int)( randFloat * ( onePastRange - inRangeStart ) );
return magnitude + inRangeStart;
}
inline double CustomRandomSource::getRandomBoundedDouble( double inRangeStart,
double inRangeEnd ) {
// double in range [0,1]
double randDouble = getRandomDouble();
double magnitude = randDouble * ( inRangeEnd - inRangeStart );
return magnitude + inRangeStart;
}
inline char CustomRandomSource::getRandomBoolean() {
// float in range [0,1]
double randFloat = getRandomFloat();
if( randFloat < 0.5 ) {
return true;
}
else {
return false;
}
}
#endif
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