1 /* $OpenBSD: flt_rounds.c,v 1.2 2022/12/27 17:10:05 jmc Exp $ */
2 /* $NetBSD: flt_rounds.c,v 1.1 2000/12/29 20:13:48 bjh21 Exp $ */
3
4 /*
5 * Copyright (c) 1996 Mark Brinicombe
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by Mark Brinicombe
19 * for the NetBSD Project.
20 * 4. The name of the author may not be used to endorse or promote products
21 * derived from this software without specific prior written permission
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 */
34
35 #include <sys/types.h>
36 #include <ieeefp.h>
37 #include <float.h>
38
39 static const int map[] = {
40 1, /* round to nearest */
41 2, /* round to positive infinity */
42 3, /* round to negative infinity */
43 0 /* round to zero */
44 };
45
46 /*
47 * Return the current FP rounding mode
48 *
49 * Returns:
50 * 0 - round to zero
51 * 1 - round to nearest
52 * 2 - round to positive infinity
53 * 3 - round to negative infinity
54 *
55 * ok all we need to do is get the current FP rounding mode
56 * index our map table and return the appropriate value.
57 *
58 * HOWEVER:
59 * The ARM FPA codes the rounding mode into the actual FP instructions
60 * so there is no such thing as a global rounding mode.
61 * The default is round to nearest if rounding is not explicitly specified.
62 * FP instructions generated by GCC will not explicitly specify a rounding
63 * mode.
64 *
65 * So the best we can do it to return the rounding mode FP instructions
66 * use if rounding is not specified which is round to nearest.
67 *
68 * This could change in the future with new floating point emulators or
69 * soft float FP libraries.
70 */
71
72 int
__flt_rounds()73 __flt_rounds()
74 {
75 return(map[fpgetround()]);
76 }
77 DEF_STRONG(__flt_rounds);
78