1 /* Install given floating-point environment. 2 Copyright (C) 2001-2021 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 #include <fenv.h> 20 #include <fpu_control.h> 21 #include <assert.h> 22 23 24 /* All exceptions, including the x86-specific "denormal operand" 25 exception. */ 26 #define FE_ALL_EXCEPT_X86 (FE_ALL_EXCEPT | __FE_DENORM) 27 28 29 int __fesetenv(const fenv_t * envp)30__fesetenv (const fenv_t *envp) 31 { 32 fenv_t temp; 33 34 /* Install the environment specified by ENVP. But there are a few 35 values which we do not want to come from the saved environment. 36 Therefore, we get the current environment and replace the values 37 we want to use from the environment specified by the parameter. */ 38 __asm__ ("fnstenv %0\n" 39 "stmxcsr %1" : "=m" (*&temp), "=m" (*&temp.__mxcsr)); 40 41 if (envp == FE_DFL_ENV) 42 { 43 temp.__control_word |= FE_ALL_EXCEPT_X86; 44 temp.__control_word &= ~FE_TOWARDZERO; 45 temp.__control_word |= _FPU_EXTENDED; 46 temp.__status_word &= ~FE_ALL_EXCEPT_X86; 47 temp.__eip = 0; 48 temp.__cs_selector = 0; 49 temp.__opcode = 0; 50 temp.__data_offset = 0; 51 temp.__data_selector = 0; 52 /* Clear SSE exceptions. */ 53 temp.__mxcsr &= ~FE_ALL_EXCEPT_X86; 54 /* Set mask for SSE MXCSR. */ 55 temp.__mxcsr |= (FE_ALL_EXCEPT_X86 << 7); 56 /* Set rounding to FE_TONEAREST. */ 57 temp.__mxcsr &= ~ 0x6000; 58 temp.__mxcsr |= (FE_TONEAREST << 3); 59 /* Clear the FZ and DAZ bits. */ 60 temp.__mxcsr &= ~0x8040; 61 } 62 else if (envp == FE_NOMASK_ENV) 63 { 64 temp.__control_word &= ~(FE_ALL_EXCEPT | FE_TOWARDZERO); 65 /* Keep the "denormal operand" exception masked. */ 66 temp.__control_word |= __FE_DENORM; 67 temp.__control_word |= _FPU_EXTENDED; 68 temp.__status_word &= ~FE_ALL_EXCEPT_X86; 69 temp.__eip = 0; 70 temp.__cs_selector = 0; 71 temp.__opcode = 0; 72 temp.__data_offset = 0; 73 temp.__data_selector = 0; 74 /* Clear SSE exceptions. */ 75 temp.__mxcsr &= ~FE_ALL_EXCEPT_X86; 76 /* Set mask for SSE MXCSR. */ 77 /* Set rounding to FE_TONEAREST. */ 78 temp.__mxcsr &= ~ 0x6000; 79 temp.__mxcsr |= (FE_TONEAREST << 3); 80 /* Do not mask exceptions. */ 81 temp.__mxcsr &= ~(FE_ALL_EXCEPT << 7); 82 /* Keep the "denormal operand" exception masked. */ 83 temp.__mxcsr |= (__FE_DENORM << 7); 84 /* Clear the FZ and DAZ bits. */ 85 temp.__mxcsr &= ~0x8040; 86 } 87 else 88 { 89 temp.__control_word &= ~(FE_ALL_EXCEPT_X86 90 | FE_TOWARDZERO 91 | _FPU_EXTENDED); 92 temp.__control_word |= (envp->__control_word 93 & (FE_ALL_EXCEPT_X86 94 | FE_TOWARDZERO 95 | _FPU_EXTENDED)); 96 temp.__status_word &= ~FE_ALL_EXCEPT_X86; 97 temp.__status_word |= envp->__status_word & FE_ALL_EXCEPT_X86; 98 temp.__eip = envp->__eip; 99 temp.__cs_selector = envp->__cs_selector; 100 temp.__opcode = envp->__opcode; 101 temp.__data_offset = envp->__data_offset; 102 temp.__data_selector = envp->__data_selector; 103 temp.__mxcsr = envp->__mxcsr; 104 } 105 106 __asm__ ("fldenv %0\n" 107 "ldmxcsr %1" : : "m" (temp), "m" (temp.__mxcsr)); 108 109 /* Success. */ 110 return 0; 111 } 112 libm_hidden_def (__fesetenv) 113 weak_alias (__fesetenv, fesetenv) 114 libm_hidden_weak (fesetenv) 115