1 | /* Install given floating-point environment. |
2 | Copyright (C) 1997-2022 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 <fpu_control.h> |
21 | #include <assert.h> |
22 | #include <unistd.h> |
23 | #include <ldsodefs.h> |
24 | #include <dl-procinfo.h> |
25 | |
26 | |
27 | /* All exceptions, including the x86-specific "denormal operand" |
28 | exception. */ |
29 | #define FE_ALL_EXCEPT_X86 (FE_ALL_EXCEPT | __FE_DENORM) |
30 | |
31 | |
32 | int |
33 | __fesetenv (const fenv_t *envp) |
34 | { |
35 | fenv_t temp; |
36 | |
37 | /* The memory block used by fstenv/fldenv has a size of 28 bytes. */ |
38 | assert (sizeof (fenv_t) == 28); |
39 | |
40 | /* Install the environment specified by ENVP. But there are a few |
41 | values which we do not want to come from the saved environment. |
42 | Therefore, we get the current environment and replace the values |
43 | we want to use from the environment specified by the parameter. */ |
44 | __asm__ ("fnstenv %0" : "=m" (*&temp)); |
45 | |
46 | if (envp == FE_DFL_ENV) |
47 | { |
48 | temp.__control_word |= FE_ALL_EXCEPT_X86; |
49 | temp.__control_word &= ~FE_TOWARDZERO; |
50 | temp.__control_word |= _FPU_EXTENDED; |
51 | temp.__status_word &= ~FE_ALL_EXCEPT_X86; |
52 | } |
53 | else if (envp == FE_NOMASK_ENV) |
54 | { |
55 | temp.__control_word &= ~(FE_ALL_EXCEPT | FE_TOWARDZERO); |
56 | /* Keep the "denormal operand" exception masked. */ |
57 | temp.__control_word |= __FE_DENORM; |
58 | temp.__control_word |= _FPU_EXTENDED; |
59 | temp.__status_word &= ~FE_ALL_EXCEPT_X86; |
60 | } |
61 | else |
62 | { |
63 | temp.__control_word &= ~(FE_ALL_EXCEPT_X86 |
64 | | FE_TOWARDZERO |
65 | | _FPU_EXTENDED); |
66 | temp.__control_word |= (envp->__control_word |
67 | & (FE_ALL_EXCEPT_X86 |
68 | | FE_TOWARDZERO |
69 | | _FPU_EXTENDED)); |
70 | temp.__status_word &= ~FE_ALL_EXCEPT_X86; |
71 | temp.__status_word |= envp->__status_word & FE_ALL_EXCEPT_X86; |
72 | } |
73 | temp.__eip = 0; |
74 | temp.__cs_selector = 0; |
75 | temp.__opcode = 0; |
76 | temp.__data_offset = 0; |
77 | temp.__data_selector = 0; |
78 | |
79 | __asm__ ("fldenv %0" : : "m" (temp)); |
80 | |
81 | if (CPU_FEATURE_USABLE (SSE)) |
82 | { |
83 | unsigned int mxcsr; |
84 | __asm__ ("stmxcsr %0" : "=m" (mxcsr)); |
85 | |
86 | if (envp == FE_DFL_ENV) |
87 | { |
88 | /* Clear SSE exceptions. */ |
89 | mxcsr &= ~FE_ALL_EXCEPT_X86; |
90 | /* Set mask for SSE MXCSR. */ |
91 | mxcsr |= (FE_ALL_EXCEPT_X86 << 7); |
92 | /* Set rounding to FE_TONEAREST. */ |
93 | mxcsr &= ~0x6000; |
94 | mxcsr |= (FE_TONEAREST << 3); |
95 | /* Clear the FZ and DAZ bits. */ |
96 | mxcsr &= ~0x8040; |
97 | } |
98 | else if (envp == FE_NOMASK_ENV) |
99 | { |
100 | /* Clear SSE exceptions. */ |
101 | mxcsr &= ~FE_ALL_EXCEPT_X86; |
102 | /* Do not mask exceptions. */ |
103 | mxcsr &= ~(FE_ALL_EXCEPT << 7); |
104 | /* Keep the "denormal operand" exception masked. */ |
105 | mxcsr |= (__FE_DENORM << 7); |
106 | /* Set rounding to FE_TONEAREST. */ |
107 | mxcsr &= ~0x6000; |
108 | mxcsr |= (FE_TONEAREST << 3); |
109 | /* Clear the FZ and DAZ bits. */ |
110 | mxcsr &= ~0x8040; |
111 | } |
112 | else |
113 | mxcsr = envp->__eip; |
114 | |
115 | __asm__ ("ldmxcsr %0" : : "m" (mxcsr)); |
116 | } |
117 | |
118 | /* Success. */ |
119 | return 0; |
120 | } |
121 | |
122 | #include <shlib-compat.h> |
123 | #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2) |
124 | strong_alias (__fesetenv, __old_fesetenv) |
125 | compat_symbol (libm, __old_fesetenv, fesetenv, GLIBC_2_1); |
126 | #endif |
127 | |
128 | libm_hidden_def (__fesetenv) |
129 | libm_hidden_ver (__fesetenv, fesetenv) |
130 | versioned_symbol (libm, __fesetenv, fesetenv, GLIBC_2_2); |
131 | |