sysdeps/powerpc/fpu/feupdateenv.c

   1 /* Install given floating-point environment and raise exceptions.
   2    Copyright (C) 1997, 1999, 2000, 2001, 2007, 2008
   3    Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, write to the Free
  19    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20    02111-1307 USA.  */
  21
  22 #include <fenv_libc.h>
  23 #include <fpu_control.h>
  24 #include <bp-sym.h>
  25
  26 #define _FPU_MASK_ALL (_FPU_MASK_ZM | _FPU_MASK_OM | _FPU_MASK_UM | _FPU_MASK_XM | _FPU_MASK_IM)
  27
  28 int
  29 __feupdateenv (const fenv_t *envp)
  30 {
  31   fenv_union_t old, new;
  32
  33   /* Save the currently set exceptions.  */
  34   new.fenv = *envp;
  35   old.fenv = fegetenv_register ();
  36
  37   /* Restore rounding mode and exception enable from *envp and merge
  38      exceptions.  Leave fraction rounded/inexact and FP result/CC bits
  39      unchanged.  */
  40   new.l[1] = (old.l[1] & 0x1FFFFF00) | (new.l[1] & 0x1FF80FFF);
  41
  42   /* If the old env has no eabled exceptions and the new env has any enabled
  43      exceptions, then unmask SIGFPE in the MSR FE0/FE1 bits.  This will put
  44      the hardware into "precise mode" and may cause the FPU to run slower on
  45      some hardware.  */
  46   if ((old.l[1] & _FPU_MASK_ALL) == 0 && (new.l[1] & _FPU_MASK_ALL) != 0)
  47     (void)__fe_nomask_env ();
  48
  49   /* If the old env had any eabled exceptions and the new env has no enabled
  50      exceptions, then mask SIGFPE in the MSR FE0/FE1 bits.  This may allow the
  51      FPU to run faster because it always takes the default action and can not
  52      generate SIGFPE. */
  53   if ((old.l[1] & _FPU_MASK_ALL) != 0 && (new.l[1] & _FPU_MASK_ALL) == 0)
  54     (void)__fe_mask_env ();
  55
  56   /* Atomically enable and raise (if appropriate) exceptions set in `new'. */
  57   fesetenv_register (new.fenv);
  58
  59   /* Success.  */
  60   return 0;
  61 }
  62
  63 #include <shlib-compat.h>
  64 #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
  65 strong_alias (__feupdateenv, __old_feupdateenv)
  66 compat_symbol (libm, BP_SYM (__old_feupdateenv), BP_SYM (feupdateenv), GLIBC_2_1);
  67 #endif
  68
  69 versioned_symbol (libm, BP_SYM (__feupdateenv), BP_SYM (feupdateenv), GLIBC_2_2);