1 /* $OpenBSD: flt_rounds.c,v 1.7 2015/10/27 05:54:49 guenther Exp $ */
2 /* $NetBSD: flt_rounds.c,v 1.1 1995/04/29 05:09:53 cgd Exp $ */
3
4 /*
5 * Copyright (c) 1995 Christopher G. Demetriou
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 Christopher G. Demetriou
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 <float.h>
37
38 static const int map[] = {
39 0, /* round to zero */
40 3, /* round to negative infinity */
41 1, /* round to nearest */
42 2 /* round to positive infinity */
43 };
44
45 int
__flt_rounds()46 __flt_rounds()
47 {
48 double fpcrval;
49 u_int64_t old;
50
51 __asm__("trapb");
52 __asm__("mf_fpcr %0" : "=f" (fpcrval));
53 __asm__("trapb");
54 old = *(u_int64_t *)&fpcrval;
55
56 return map[(old >> 58) & 0x3];
57 }
58 DEF_STRONG(__flt_rounds);
59