1 | /* Set given exception flags. i386 version. |
2 | Copyright (C) 2016-2024 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 | #include <fenv.h> |
20 | #include <ldsodefs.h> |
21 | |
22 | int |
23 | fesetexcept (int excepts) |
24 | { |
25 | /* The flags can be set in the 387 unit or in the SSE unit. To set a flag, |
26 | it is sufficient to do it in the SSE unit, because that is guaranteed to |
27 | not trap. However, on i386 CPUs that have only a 387 unit, set the flags |
28 | in the 387, as long as this cannot trap. */ |
29 | |
30 | excepts &= FE_ALL_EXCEPT; |
31 | |
32 | if (CPU_FEATURE_USABLE (SSE)) |
33 | { |
34 | /* Get the control word of the SSE unit. */ |
35 | unsigned int mxcsr; |
36 | __asm__ ("stmxcsr %0" : "=m" (*&mxcsr)); |
37 | |
38 | /* Set relevant flags. */ |
39 | mxcsr |= excepts; |
40 | |
41 | /* Put the new data in effect. */ |
42 | __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr)); |
43 | } |
44 | else |
45 | { |
46 | fenv_t temp; |
47 | |
48 | /* Note: fnstenv masks all floating-point exceptions until the fldenv |
49 | or fldcw below. */ |
50 | __asm__ ("fnstenv %0" : "=m" (*&temp)); |
51 | |
52 | /* Set relevant flags. */ |
53 | temp.__status_word |= excepts; |
54 | |
55 | if ((~temp.__control_word) & excepts) |
56 | { |
57 | /* Setting the exception flags may trigger a trap (at the next |
58 | floating-point instruction, but that does not matter). |
59 | ISO C23 (7.6.4.4) does not allow it. */ |
60 | __asm__ volatile ("fldcw %0" : : "m" (*&temp.__control_word)); |
61 | return -1; |
62 | } |
63 | |
64 | /* Store the new status word (along with the rest of the environment). */ |
65 | __asm__ ("fldenv %0" : : "m" (*&temp)); |
66 | } |
67 | |
68 | return 0; |
69 | } |
70 | |