/*
 ============================================================================
 Name        : kongruencia.c
 Author      : Stippinger Marcell
 Version     : 1.0
 Copyright   : BME-TTK FI SzamSzim gyak segedanyag
 Description : multiplicative congruential RNG in C, Ansi-style
 ============================================================================
 */

#include "kongruencia.h"
#include <stdlib.h>

/* Allocate an RNG and initialize parameters */
my_rng* my_rng_alloc(unsigned int a, unsigned int m, unsigned int c)
{
	my_rng* r;
	r = calloc(1,sizeof(my_rng));
	if (r!=NULL)
	{
		if ((a!=0)&&(m!=0)){
			r->a = a;
			r->m = m;
			r->c = c;
		} else {
			// Default values from the course slides
			r->a = 16807;
			r->m = 2147483647;
			r->c = 0;
		}
	}
	return r;
}

/* Set seed */
void my_rng_set(my_rng* r, unsigned int seed) {
	r->seed = seed;
}

/* Get a random int */
unsigned int my_rng_get(my_rng* r) {
	r->seed = (r->a*r->seed+r->c)%r->m;
	return r->seed;
}

/* Get boundaries */
unsigned int my_rng_min(my_rng* r) {
	return 0;
}
unsigned int my_rng_max(my_rng* r) {
	return r->m-1;
}

/* Get a random double in [0,1) */
double my_rng_uniform(my_rng* r) {
	r->seed = (r->a*r->seed+r->c)%r->m;
	return r->seed/(double)(r->m);
}

/* Free allocated space */
void my_rng_free(my_rng* r) {
	free(r);
}