1/* Determine floating-point rounding mode within libc. Generic version.
2 Copyright (C) 2012-2020 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#ifndef _GET_ROUNDING_MODE_H
20#define _GET_ROUNDING_MODE_H 1
21
22#include <fpu_control.h>
23#include <stdlib.h>
24
25/* Define values for FE_* modes not defined for this architecture. */
26#ifdef FE_DOWNWARD
27# define ORIG_FE_DOWNWARD FE_DOWNWARD
28#else
29# define ORIG_FE_DOWNWARD 0
30#endif
31#ifdef FE_TONEAREST
32# define ORIG_FE_TONEAREST FE_TONEAREST
33#else
34# define ORIG_FE_TONEAREST 0
35#endif
36#ifdef FE_TOWARDZERO
37# define ORIG_FE_TOWARDZERO FE_TOWARDZERO
38#else
39# define ORIG_FE_TOWARDZERO 0
40#endif
41#ifdef FE_UPWARD
42# define ORIG_FE_UPWARD FE_UPWARD
43#else
44# define ORIG_FE_UPWARD 0
45#endif
46#define FE_CONSTRUCT_DISTINCT_VALUE(X, Y, Z) \
47 ((((X) & 1) | ((Y) & 2) | ((Z) & 4)) ^ 7)
48#ifndef FE_DOWNWARD
49# define FE_DOWNWARD FE_CONSTRUCT_DISTINCT_VALUE (ORIG_FE_TONEAREST, \
50 ORIG_FE_TOWARDZERO, \
51 ORIG_FE_UPWARD)
52#endif
53#ifndef FE_TONEAREST
54# define FE_TONEAREST FE_CONSTRUCT_DISTINCT_VALUE (FE_DOWNWARD, \
55 ORIG_FE_TOWARDZERO, \
56 ORIG_FE_UPWARD)
57#endif
58#ifndef FE_TOWARDZERO
59# define FE_TOWARDZERO FE_CONSTRUCT_DISTINCT_VALUE (FE_DOWNWARD, \
60 FE_TONEAREST, \
61 ORIG_FE_UPWARD)
62#endif
63#ifndef FE_UPWARD
64# define FE_UPWARD FE_CONSTRUCT_DISTINCT_VALUE (FE_DOWNWARD, \
65 FE_TONEAREST, \
66 FE_TOWARDZERO)
67#endif
68
69/* Return the floating-point rounding mode. */
70
71static inline int
72get_rounding_mode (void)
73{
74#if (defined _FPU_RC_DOWN \
75 || defined _FPU_RC_NEAREST \
76 || defined _FPU_RC_ZERO \
77 || defined _FPU_RC_UP)
78 fpu_control_t fc;
79 const fpu_control_t mask = (0
80# ifdef _FPU_RC_DOWN
81 | _FPU_RC_DOWN
82# endif
83# ifdef _FPU_RC_NEAREST
84 | _FPU_RC_NEAREST
85# endif
86# ifdef _FPU_RC_ZERO
87 | _FPU_RC_ZERO
88# endif
89# ifdef _FPU_RC_UP
90 | _FPU_RC_UP
91# endif
92 );
93
94 _FPU_GETCW (fc);
95 switch (fc & mask)
96 {
97# ifdef _FPU_RC_DOWN
98 case _FPU_RC_DOWN:
99 return FE_DOWNWARD;
100# endif
101
102# ifdef _FPU_RC_NEAREST
103 case _FPU_RC_NEAREST:
104 return FE_TONEAREST;
105# endif
106
107# ifdef _FPU_RC_ZERO
108 case _FPU_RC_ZERO:
109 return FE_TOWARDZERO;
110# endif
111
112# ifdef _FPU_RC_UP
113 case _FPU_RC_UP:
114 return FE_UPWARD;
115# endif
116
117 default:
118 abort ();
119 }
120#else
121 return FE_TONEAREST;
122#endif
123}
124
125#endif /* get-rounding-mode.h */
126