sysdeps/powerpc/fpu/feupdateenv.c

   1 /* Install given floating-point environment and raise exceptions.
   2    Copyright (C) 1997, 1999, 2000, 2001, 2007, 2008, 2010
   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, see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21 #include <fenv_libc.h>
  22 #include <fpu_control.h>
  23 #include <bp-sym.h>
  24
  25 #define _FPU_MASK_ALL (_FPU_MASK_ZM | _FPU_MASK_OM | _FPU_MASK_UM | _FPU_MASK_XM | _FPU_MASK_IM)
  26
  27 int
  28 __feupdateenv (const fenv_t *envp)
  29 {
  30   fenv_union_t old, new;
  31
  32   /* Save the currently set exceptions.  */
  33   new.fenv = *envp;
  34   old.fenv = fegetenv_register ();
  35
  36   /* Restore rounding mode and exception enable from *envp and merge
  37      exceptions.  Leave fraction rounded/inexact and FP result/CC bits
  38      unchanged.  */
  39   new.l[1] = (old.l[1] & 0x1FFFFF00) | (new.l[1] & 0x1FF80FFF);
  40
  41   /* If the old env has no eabled exceptions and the new env has any enabled
  42      exceptions, then unmask SIGFPE in the MSR FE0/FE1 bits.  This will put
  43      the hardware into "precise mode" and may cause the FPU to run slower on
  44      some hardware.  */
  45   if ((old.l[1] & _FPU_MASK_ALL) == 0 && (new.l[1] & _FPU_MASK_ALL) != 0)
  46     (void)__fe_nomask_env ();
  47
  48   /* If the old env had any eabled exceptions and the new env has no enabled
  49      exceptions, then mask SIGFPE in the MSR FE0/FE1 bits.  This may allow the
  50      FPU to run faster because it always takes the default action and can not
  51      generate SIGFPE. */
  52   if ((old.l[1] & _FPU_MASK_ALL) != 0 && (new.l[1] & _FPU_MASK_ALL) == 0)
  53     (void)__fe_mask_env ();
  54
  55   /* Atomically enable and raise (if appropriate) exceptions set in `new'. */
  56   fesetenv_register (new.fenv);
  57
  58   /* Success.  */
  59   return 0;
  60 }
  61
  62 #include <shlib-compat.h>
  63 #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
  64 strong_alias (__feupdateenv, __old_feupdateenv)
  65 compat_symbol (libm, BP_SYM (__old_feupdateenv), BP_SYM (feupdateenv), GLIBC_2_1);
  66 #endif
  67
  68 libm_hidden_ver (__feupdateenv, feupdateenv)
  69 versioned_symbol (libm, BP_SYM (__feupdateenv), BP_SYM (feupdateenv), GLIBC_2_2);