1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 "quad.h"
37
38 #define ONE_FOURTH (1L << (LONG_BITS - 2))
39 #define ONE_HALF (ONE_FOURTH * 2.0)
40 #define ONE (ONE_FOURTH * 4.0)
41
42 /*
43 * Convert float to (unsigned) quad. We do most of our work in double,
44 * out of sheer paranoia.
45 *
46 * Not sure what to do with negative numbers---for now, anything out
47 * of range becomes UQUAD_MAX.
48 *
49 * N.B.: must use new ANSI syntax (sorry).
50 */
51 u_quad_t
__fixunssfdi(float f)52 __fixunssfdi(float f)
53 {
54 double x, toppart;
55 union uu t;
56
57 if (f < 0)
58 return (UQUAD_MAX); /* ??? should be 0? ERANGE??? */
59 #ifdef notdef /* this falls afoul of a GCC bug */
60 if (f >= UQUAD_MAX)
61 return (UQUAD_MAX);
62 #else /* so we wire in 2^64-1 instead */
63 if (f >= 18446744073709551615.0)
64 return (UQUAD_MAX);
65 #endif
66 x = f;
67 /*
68 * Get the upper part of the result. Note that the divide
69 * may round up; we want to avoid this if possible, so we
70 * subtract `1/2' first.
71 */
72 toppart = (x - ONE_HALF) / ONE;
73 /*
74 * Now build a u_quad_t out of the top part. The difference
75 * between x and this is the bottom part (this may introduce
76 * a few fuzzy bits, but what the heck). With any luck this
77 * difference will be nonnegative: x should wind up in the
78 * range [0..ULONG_MAX]. For paranoia, we assume [LONG_MIN..
79 * 2*ULONG_MAX] instead.
80 */
81 t.ul[H] = (unsigned long)toppart;
82 t.ul[L] = 0;
83 x -= (double)t.uq;
84 if (x < 0) {
85 t.ul[H]--;
86 x += (double)ULONG_MAX;
87 }
88 if (x > (double)ULONG_MAX) {
89 t.ul[H]++;
90 x -= (double)ULONG_MAX;
91 }
92 t.ul[L] = (u_long)x;
93 return (t.uq);
94 }
95