random.c

/*
 * Elite - The New Kind.
 *
 * Reverse engineered from the BBC disk version of Elite.
 * Additional material by C.J.Pinder.
 *
 * The original Elite code is (C) I.Bell & D.Braben 1984.
 * This version re-engineered in C by C.J.Pinder 1999-2001.
 *
 * email: <christian@newkind.co.uk>
 *
 *
 */

/*
 * random.c
 */
 
 
#include <stdlib.h>
#include "allegro.h"

#include "random.h"

static int rand_seed;

/*
 * Portable random number generator implementing the recursion:
 *     IX = 16807 * IX MOD (2**(31) - 1)
 * Using only 32 bits, including sign.
 *
 * Taken from "A Guide to Simulation" by Bratley, Fox and Schrage.
 */

int randint (void)
{
	int k1;
	int ix = rand_seed;
	
	k1 = ix / 127773;
	ix = 16807 * (ix - k1 * 127773) - k1 * 2836;
	if (ix < 0)
		ix += 2147483647;
	rand_seed = ix;

	return ix; 
}
 

void set_rand_seed (int seed)
{
	rand_seed = seed;
}


int get_rand_seed (void)
{
	return rand_seed;
}

int rand255 (void)
{
	return (randint() & 255);
}