1/*-
2 * Copyright (c) 1992, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This software was developed by the Computer Systems Engineering group
6 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
7 * contributed to Berkeley.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#if defined(LIBC_SCCS) && !defined(lint)
35static char sccsid[] = "@(#)fixunssfdi.c	8.1 (Berkeley) 6/4/93";
36#endif /* LIBC_SCCS and not lint */
37#include <sys/cdefs.h>
38__FBSDID("$FreeBSD$");
39
40#include "quad.h"
41
42#define	ONE_FOURTH	(1 << (LONG_BITS - 2))
43#define	ONE_HALF	(ONE_FOURTH * 2.0)
44#define	ONE		(ONE_FOURTH * 4.0)
45
46/*
47 * Convert float to (unsigned) quad.  We do most of our work in double,
48 * out of sheer paranoia.
49 *
50 * Not sure what to do with negative numbers---for now, anything out
51 * of range becomes UQUAD_MAX.
52 *
53 * N.B.: must use new ANSI syntax (sorry).
54 */
55u_quad_t
56__fixunssfdi(float f)
57{
58	double x, toppart;
59	union uu t;
60
61	if (f < 0)
62		return (UQUAD_MAX);	/* ??? should be 0?  ERANGE??? */
63#ifdef notdef				/* this falls afoul of a GCC bug */
64	if (f >= UQUAD_MAX)
65		return (UQUAD_MAX);
66#else					/* so we wire in 2^64-1 instead */
67	if (f >= 18446744073709551615.0)
68		return (UQUAD_MAX);
69#endif
70	x = f;
71	/*
72	 * Get the upper part of the result.  Note that the divide
73	 * may round up; we want to avoid this if possible, so we
74	 * subtract `1/2' first.
75	 */
76	toppart = (x - ONE_HALF) / ONE;
77	/*
78	 * Now build a u_quad_t out of the top part.  The difference
79	 * between x and this is the bottom part (this may introduce
80	 * a few fuzzy bits, but what the heck).  With any luck this
81	 * difference will be nonnegative: x should wind up in the
82	 * range [0..ULONG_MAX].  For paranoia, we assume [LONG_MIN..
83	 * 2*ULONG_MAX] instead.
84	 */
85	t.ul[H] = (unsigned long)toppart;
86	t.ul[L] = 0;
87	x -= (double)t.uq;
88	if (x < 0) {
89		t.ul[H]--;
90		x += ULONG_MAX;
91	}
92	if (x > ULONG_MAX) {
93		t.ul[H]++;
94		x -= ULONG_MAX;
95	}
96	t.ul[L] = (u_long)x;
97	return (t.uq);
98}
99