sysdeps/i386/fpu/fesetenv.c

   1 /* Install given floating-point environment.
   2    Copyright (C) 1997-2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <fenv.h>
  21 #include <assert.h>
  22
  23
  24 int
  25 __fesetenv (const fenv_t *envp)
  26 {
  27   fenv_t temp;
  28
  29   /* The memory block used by fstenv/fldenv has a size of 28 bytes.  */
  30   assert (sizeof (fenv_t) == 28);
  31
  32   /* Install the environment specified by ENVP.  But there are a few
  33      values which we do not want to come from the saved environment.
  34      Therefore, we get the current environment and replace the values
  35      we want to use from the environment specified by the parameter.  */
  36   __asm__ ("fnstenv %0" : "=m" (*&temp));
  37
  38   if (envp == FE_DFL_ENV)
  39     {
  40       temp.__control_word |= FE_ALL_EXCEPT;
  41       temp.__control_word &= ~FE_TOWARDZERO;
  42       temp.__status_word &= ~FE_ALL_EXCEPT;
  43       temp.__eip = 0;
  44       temp.__cs_selector = 0;
  45       temp.__opcode = 0;
  46       temp.__data_offset = 0;
  47       temp.__data_selector = 0;
  48     }
  49   else if (envp == FE_NOMASK_ENV)
  50     {
  51       temp.__control_word &= ~(FE_ALL_EXCEPT | FE_TOWARDZERO);
  52       temp.__status_word &= ~FE_ALL_EXCEPT;
  53       temp.__eip = 0;
  54       temp.__cs_selector = 0;
  55       temp.__opcode = 0;
  56       temp.__data_offset = 0;
  57       temp.__data_selector = 0;
  58     }
  59   else
  60     {
  61       temp.__control_word &= ~(FE_ALL_EXCEPT | FE_TOWARDZERO);
  62       temp.__control_word |= (envp->__control_word
  63                               & (FE_ALL_EXCEPT | FE_TOWARDZERO));
  64       temp.__status_word &= ~FE_ALL_EXCEPT;
  65       temp.__status_word |= envp->__status_word & FE_ALL_EXCEPT;
  66       temp.__eip = envp->__eip;
  67       temp.__cs_selector = envp->__cs_selector;
  68       temp.__opcode = envp->__opcode;
  69       temp.__data_offset = envp->__data_offset;
  70       temp.__data_selector = envp->__data_selector;
  71     }
  72
  73   __asm__ ("fldenv %0" : : "m" (temp));
  74
  75   /* Success.  */
  76   return 0;
  77 }
  78
  79 #include <shlib-compat.h>
  80 #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
  81 strong_alias (__fesetenv, __old_fesetenv)
  82 compat_symbol (libm, __old_fesetenv, fesetenv, GLIBC_2_1);
  83 #endif
  84
  85 libm_hidden_ver (__fesetenv, fesetenv)
  86 versioned_symbol (libm, __fesetenv, fesetenv, GLIBC_2_2);