#include"generator.h"
#include<cmath>
#include<climits>

generator::generator(int MeanEventsPerUnitTime) {
	seed=1;
	mean=MeanEventsPerUnitTime;
}

void generator::SetMean(int MeanEventsPerUnitTime) {
	mean=MeanEventsPerUnitTime;
}

int generator::GetNumberOfEvents() {
	double limit=exp(-mean);
	double product=GetRandomNumber();
	int count=0;
	while (product > limit) {
		count++;
		product*=GetRandomNumber();
	}
	return count;	
}

double generator::GetRandomNumber() {
	double max = INT_MAX + 1.0;
	seed = seed * 2743 + 5923; //generate a pseudorandom int.
	if (seed < 0)	
		seed = seed + max; //shift back into the positive numbers.
	return(seed/max); //scale to the range (0,1)
}