fixunsdfdi.c revision 1.9 
1/*	$NetBSD: fixunsdfdi.c,v 1.9 2012/03/13 21:13:42 christos Exp $	*/
2
3/*-
4 * Copyright (c) 1992, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This software was developed by the Computer Systems Engineering group
8 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9 * contributed to Berkeley.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#include <sys/cdefs.h>
37#if defined(LIBC_SCCS) && !defined(lint)
38#if 0
39static char sccsid[] = "@(#)fixunsdfdi.c	8.1 (Berkeley) 6/4/93";
40#else
41__RCSID("$NetBSD: fixunsdfdi.c,v 1.9 2012/03/13 21:13:42 christos Exp $");
42#endif
43#endif /* LIBC_SCCS and not lint */
44
45#include "quad.h"
46
47#define	ONE_FOURTH	((int)1 << (unsigned int)(INT_BITS - 2))
48#define	ONE_HALF	(ONE_FOURTH * 2.0)
49#define	ONE		(ONE_FOURTH * 4.0)
50
51/*
52 * Convert double to (unsigned) quad.
53 * Not sure what to do with negative numbers---for now, anything out
54 * of range becomes UQUAD_MAX.
55 */
56u_quad_t
57__fixunsdfdi(double x)
58{
59	union uu t;
60	unsigned int tmp;
61
62	if (x < 0)
63		return (UQUAD_MAX);	/* ??? should be 0?  ERANGE??? */
64#ifdef notdef				/* this falls afoul of a GCC bug */
65	if (x >= UQUAD_MAX)
66		return (UQUAD_MAX);
67#else					/* so we wire in 2^64-1 instead */
68	if (x >= 18446744073709551615.0)	/* XXX */
69		return (UQUAD_MAX);
70#endif
71	/*
72	 * Now we know that 0 <= x <= 18446744073709549568.  The upper
73	 * limit is one ulp less than 18446744073709551615 tested for above.
74	 * Dividing this by 2^32 will *not* round irrespective of any
75	 * rounding modes (except if the result is an IEEE denorm).
76	 * Furthermore, the quotient will fit into a 32-bit integer.
77	 */
78	tmp = x / ONE;
79	t.ul[L] = (unsigned int) (x - tmp * ONE);
80	t.ul[H] = tmp;
81	return (t.uq);
82}
83