1 /* Determine floating-point rounding mode within libc. Generic version.
2 Copyright (C) 2012-2021 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
71 static inline int
get_rounding_mode(void)72 get_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