1/*	$NetBSD: erand48_ieee754.c,v 1.1 2006/03/22 21:06:03 drochner Exp $	*/
2
3/*
4 * Copyright (c) 1993 Martin Birgmeier
5 * All rights reserved.
6 *
7 * You may redistribute unmodified or modified versions of this source
8 * code provided that the above copyright notice and this and the
9 * following conditions are retained.
10 *
11 * This software is provided ``as is'', and comes with no warranties
12 * of any kind. I shall in no event be liable for anything that happens
13 * to anyone/anything when using this software.
14 */
15
16#include <sys/cdefs.h>
17#if defined(LIBC_SCCS) && !defined(lint)
18__RCSID("$NetBSD: erand48_ieee754.c,v 1.1 2006/03/22 21:06:03 drochner Exp $");
19#endif /* LIBC_SCCS and not lint */
20
21#include "namespace.h"
22
23#include <assert.h>
24#include <machine/ieee.h>
25
26#include "rand48.h"
27
28#ifdef __weak_alias
29__weak_alias(erand48,_erand48)
30#endif
31
32double
33erand48(unsigned short xseed[3])
34{
35	union ieee_double_u u;
36
37	_DIAGASSERT(xseed != NULL);
38
39	__dorand48(xseed);
40	u.dblu_dbl.dbl_sign = 0;
41	u.dblu_dbl.dbl_exp = DBL_EXP_BIAS; /* so we get [1,2) */
42	u.dblu_dbl.dbl_frach = ((unsigned int)xseed[2] << 4)
43				| ((unsigned int)xseed[1] >> 12);
44	u.dblu_dbl.dbl_fracl = (((unsigned int)xseed[1] & 0x0fff) << 20)
45				| ((unsigned int)xseed[0] << 4);
46	return (u.dblu_d - 1);
47}
48