sysdeps/x86_64/fpu/fesetenv.c

   1 /* Install given floating-point environment.
   2    Copyright (C) 2001, 2002, 2003 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  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   /* Install the environment specified by ENVP.  But there are a few
  30      values which we do not want to come from the saved environment.
  31      Therefore, we get the current environment and replace the values
  32      we want to use from the environment specified by the parameter.  */
  33   __asm__ ("fnstenv %0\n"
  34            "stmxcsr %1" : "=m" (*&temp), "=m" (*&temp.__mxcsr));
  35
  36   if (envp == FE_DFL_ENV)
  37     {
  38       temp.__control_word |= FE_ALL_EXCEPT;
  39       temp.__control_word &= ~FE_TOWARDZERO;
  40       temp.__status_word &= ~FE_ALL_EXCEPT;
  41       temp.__eip = 0;
  42       temp.__cs_selector = 0;
  43       temp.__opcode = 0;
  44       temp.__data_offset = 0;
  45       temp.__data_selector = 0;
  46       /* Set mask for SSE MXCSR.  */
  47       temp.__mxcsr |= (FE_ALL_EXCEPT << 7);
  48       /* Set rounding to FE_TONEAREST.  */
  49       temp.__mxcsr &= ~ 0x6000;
  50       temp.__mxcsr |= (FE_TONEAREST << 3);
  51     }
  52   else if (envp == FE_NOMASK_ENV)
  53     {
  54       temp.__control_word &= ~(FE_ALL_EXCEPT | FE_TOWARDZERO);
  55       temp.__status_word &= ~FE_ALL_EXCEPT;
  56       temp.__eip = 0;
  57       temp.__cs_selector = 0;
  58       temp.__opcode = 0;
  59       temp.__data_offset = 0;
  60       temp.__data_selector = 0;
  61       /* Set mask for SSE MXCSR.  */
  62       /* Set rounding to FE_TONEAREST.  */
  63       temp.__mxcsr &= ~ 0x6000;
  64       temp.__mxcsr |= (FE_TONEAREST << 3);
  65       /* Do not mask exceptions.  */
  66       temp.__mxcsr &= ~(FE_ALL_EXCEPT << 7);
  67     }
  68   else
  69     {
  70       temp.__control_word &= ~(FE_ALL_EXCEPT | FE_TOWARDZERO);
  71       temp.__control_word |= (envp->__control_word
  72                               & (FE_ALL_EXCEPT | FE_TOWARDZERO));
  73       temp.__status_word &= ~FE_ALL_EXCEPT;
  74       temp.__status_word |= envp->__status_word & FE_ALL_EXCEPT;
  75       temp.__eip = envp->__eip;
  76       temp.__cs_selector = envp->__cs_selector;
  77       temp.__opcode = envp->__opcode;
  78       temp.__data_offset = envp->__data_offset;
  79       temp.__data_selector = envp->__data_selector;
  80       temp.__mxcsr = envp->__mxcsr;
  81     }
  82
  83   __asm__ ("fldenv %0\n"
  84            "ldmxcsr %1" : : "m" (temp), "m" (temp.__mxcsr));
  85
  86   /* Success.  */
  87   return 0;
  88 }
  89 libm_hidden_def (fesetenv)