1 /* $OpenBSD: fixunssfdi.c,v 1.7 2019/11/10 22:23:28 guenther Exp $ */
2 /*-
3 * Copyright (c) 1992, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * This software was developed by the Computer Systems Engineering group
7 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
8 * contributed to Berkeley.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include "quad.h"
36
37 #define ONE_FOURTH ((int)1 << (INT_BITS - 2))
38 #define ONE_HALF (ONE_FOURTH * 2.0)
39 #define ONE (ONE_FOURTH * 4.0)
40
41 /*
42 * Convert float to (unsigned) quad. We do most of our work in double,
43 * out of sheer paranoia.
44 *
45 * Not sure what to do with negative numbers---for now, anything out
46 * of range becomes UQUAD_MAX.
47 *
48 * N.B.: must use new ANSI syntax (sorry).
49 */
50 u_quad_t
__fixunssfdi(float f)51 __fixunssfdi(float f)
52 {
53 double x, toppart;
54 union uu t;
55
56 if (f < 0)
57 return (UQUAD_MAX); /* ??? should be 0? ERANGE??? */
58 #ifdef notdef /* this falls afoul of a GCC bug */
59 if (f >= UQUAD_MAX)
60 return (UQUAD_MAX);
61 #else /* so we wire in 2^64-1 instead */
62 if (f >= 18446744073709551615.0) /* XXX */
63 return (UQUAD_MAX);
64 #endif
65 x = f;
66 /*
67 * Get the upper part of the result. Note that the divide
68 * may round up; we want to avoid this if possible, so we
69 * subtract `1/2' first.
70 */
71 toppart = (x - ONE_HALF) / ONE;
72 /*
73 * Now build a u_quad_t out of the top part. The difference
74 * between x and this is the bottom part (this may introduce
75 * a few fuzzy bits, but what the heck). With any luck this
76 * difference will be nonnegative: x should wind up in the
77 * range [0..UINT_MAX]. For paranoia, we assume [INT_MIN..
78 * 2*UINT_MAX] instead.
79 */
80 t.ul[H] = (unsigned int)toppart;
81 t.ul[L] = 0;
82 x -= (double)t.uq;
83 if (x < 0) {
84 t.ul[H]--;
85 x += UINT_MAX;
86 }
87 if (x > UINT_MAX) {
88 t.ul[H]++;
89 x -= UINT_MAX;
90 }
91 t.ul[L] = (u_int)x;
92 return (t.uq);
93 }
94
95 #ifdef __ARM_EABI__
96 __strong_alias(__aeabi_f2ulz, __fixunssfdi);
97 __asm(".protected __aeabi_f2ulz");
98 #endif
99