1 /* $NetBSD: flt_rounds.c,v 1.10 2014/08/03 19:14:24 wiz Exp $ */
2
3 /*
4 * Copyright (c) 1995 Christopher G. Demetriou
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed for the
18 * NetBSD Project. See http://www.NetBSD.org/ for
19 * information about NetBSD.
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 * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
35 */
36
37 #include <sys/cdefs.h>
38 #if defined(LIBC_SCCS) && !defined(lint)
39 __RCSID("$NetBSD: flt_rounds.c,v 1.10 2014/08/03 19:14:24 wiz Exp $");
40 #endif /* LIBC_SCCS and not lint */
41
42 #include <sys/types.h>
43 #include <machine/ieeefp.h>
44 #include <machine/float.h>
45
46 /*
47 * These come from <float.h> definition
48 */
49 #define FLT_ROUND_MAP \
50 ( (0 << (FP_RZ*2)) /* round to zero */ \
51 | (1 << (FP_RN*2)) /* round to nearest */ \
52 | (3 << (FP_RM*2)) /* round to negative infinity */ \
53 | (2 << (FP_RP*2))) /* round to positive infinity */
54
55 int
__flt_rounds(void)56 __flt_rounds(void)
57 {
58 union {
59 double d;
60 uint64_t u64;
61 } fpcrval;
62 uint64_t old;
63
64 __asm("excb; mf_fpcr %0; excb" : "=f" (fpcrval.d));
65 old = (fpcrval.u64 >> 58) & 3;
66
67 return (FLT_ROUND_MAP >> (old << 1)) & 3;
68 }
69