13016Swollman/*
23016Swollman * Copyright (c) 1993 Martin Birgmeier
33016Swollman * All rights reserved.
43016Swollman *
53016Swollman * You may redistribute unmodified or modified versions of this source
63016Swollman * code provided that the above copyright notice and this and the
73016Swollman * following conditions are retained.
83016Swollman *
93016Swollman * This software is provided ``as is'', and comes with no warranties
103016Swollman * of any kind. I shall in no event be liable for anything that happens
113016Swollman * to anyone/anything when using this software.
123016Swollman */
133016Swollman
1492986Sobrien#include <sys/cdefs.h>
1592986Sobrien__FBSDID("$FreeBSD$");
1692986Sobrien
173016Swollman#include "rand48.h"
183016Swollman
193016Swollmanunsigned short _rand48_seed[3] = {
203016Swollman	RAND48_SEED_0,
213016Swollman	RAND48_SEED_1,
223016Swollman	RAND48_SEED_2
233016Swollman};
243016Swollmanunsigned short _rand48_mult[3] = {
253016Swollman	RAND48_MULT_0,
263016Swollman	RAND48_MULT_1,
273016Swollman	RAND48_MULT_2
283016Swollman};
293016Swollmanunsigned short _rand48_add = RAND48_ADD;
303016Swollman
313016Swollmanvoid
323016Swollman_dorand48(unsigned short xseed[3])
333016Swollman{
343016Swollman	unsigned long accu;
353016Swollman	unsigned short temp[2];
363016Swollman
373016Swollman	accu = (unsigned long) _rand48_mult[0] * (unsigned long) xseed[0] +
383016Swollman	 (unsigned long) _rand48_add;
393016Swollman	temp[0] = (unsigned short) accu;	/* lower 16 bits */
403016Swollman	accu >>= sizeof(unsigned short) * 8;
413016Swollman	accu += (unsigned long) _rand48_mult[0] * (unsigned long) xseed[1] +
423016Swollman	 (unsigned long) _rand48_mult[1] * (unsigned long) xseed[0];
433016Swollman	temp[1] = (unsigned short) accu;	/* middle 16 bits */
443016Swollman	accu >>= sizeof(unsigned short) * 8;
453016Swollman	accu += _rand48_mult[0] * xseed[2] + _rand48_mult[1] * xseed[1] + _rand48_mult[2] * xseed[0];
463016Swollman	xseed[0] = temp[0];
473016Swollman	xseed[1] = temp[1];
483016Swollman	xseed[2] = (unsigned short) accu;
493016Swollman}
50