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glibc  2.9
fsetexcptflg.c
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00001 /* Set floating-point environment exception handling.
00002    Copyright (C) 1998, 1999, 2000, 2002, 2004 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004    Contributed by Alexandre Oliva <aoliva@redhat.com>
00005    based on corresponding file in the MIPS port.
00006 
00007    The GNU C Library is free software; you can redistribute it and/or
00008    modify it under the terms of the GNU Lesser General Public
00009    License as published by the Free Software Foundation; either
00010    version 2.1 of the License, or (at your option) any later version.
00011 
00012    The GNU C Library is distributed in the hope that it will be useful,
00013    but WITHOUT ANY WARRANTY; without even the implied warranty of
00014    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015    Lesser General Public License for more details.
00016 
00017    You should have received a copy of the GNU Lesser General Public
00018    License along with the GNU C Library; if not, write to the Free
00019    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00020    02111-1307 USA.  */
00021 
00022 #include <fenv.h>
00023 #include <fpu_control.h>
00024 #include <shlib-compat.h>
00025 
00026 int
00027 __fesetexceptflag (const fexcept_t *flagp, int excepts)
00028 {
00029   fpu_control_t cw, temp;
00030 
00031   /* Get the current exceptions.  */
00032   _FPU_GETCW (cw);
00033 
00034   /* Make sure the flags we want restored are legal.  */
00035   excepts &= FE_ALL_EXCEPT;
00036   temp = *flagp & excepts;
00037 
00038   /* If EF bits are clear and the user requests them to be set,
00039      we have to fail, because there's no way to do it.  */
00040   if (~(cw & excepts) & temp)
00041     return -1;
00042 
00043   /* We clear EF bits by storing a 1 in them, so flip the
00044      FE_ALL_EXCEPT bits.  */
00045   temp = (~temp & FE_ALL_EXCEPT);
00046 
00047   /* Now clear the bits called for, and copy them in from flagp. Note that
00048      we ignore all non-flag bits from *flagp, so they don't matter.  */
00049   cw = (cw & ~FE_ALL_EXCEPT) | temp;
00050 
00051   _FPU_SETFCW (cw);
00052 
00053   /* Success.  */
00054   return 0;
00055 }
00056 
00057 versioned_symbol (libm, __fesetexceptflag, fesetexceptflag, GLIBC_2_2);