[newkind] / 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);
}
Commit	Line	Data
84bbd123	1	/*
	2	* Elite - The New Kind.
	3	*
	4	* Reverse engineered from the BBC disk version of Elite.
	5	* Additional material by C.J.Pinder.
	6	*
	7	* The original Elite code is (C) I.Bell & D.Braben 1984.
	8	* This version re-engineered in C by C.J.Pinder 1999-2001.
	9	*
	10	* email: <christian@newkind.co.uk>
	11	*
	12	*
	13	*/
	14
	15	/*
	16	* random.c
	17	*/
	18
	19
	20	#include <stdlib.h>
	21	#include "allegro.h"
	22
	23	#include "random.h"
	24
	25	static int rand_seed;
	26
	27	/*
	28	* Portable random number generator implementing the recursion:
	29	* IX = 16807 * IX MOD (2**(31) - 1)
	30	* Using only 32 bits, including sign.
	31	*
	32	* Taken from "A Guide to Simulation" by Bratley, Fox and Schrage.
	33	*/
	34
	35	int randint (void)
	36	{
	37	int k1;
	38	int ix = rand_seed;
	39
	40	k1 = ix / 127773;
	41	ix = 16807 * (ix - k1 * 127773) - k1 * 2836;
	42	if (ix < 0)
	43	ix += 2147483647;
	44	rand_seed = ix;
	45
	46	return ix;
	47	}
	48
	49
	50	void set_rand_seed (int seed)
	51	{
	52	rand_seed = seed;
	53	}
	54
	55
	56	int get_rand_seed (void)
	57	{
	58	return rand_seed;
	59	}
	60
	61	int rand255 (void)
	62	{
	63	return (randint() & 255);
	64	}