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glibc  2.9
feenablxcpt.c
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00001 /* Enable floating-point exceptions.
00002    Copyright (C) 2001, 2007 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004    Contributed by Andreas Jaeger <aj@suse.de>, 2001.
00005 
00006    The GNU C Library is free software; you can redistribute it and/or
00007    modify it under the terms of the GNU Lesser General Public
00008    License as published by the Free Software Foundation; either
00009    version 2.1 of the License, or (at your option) any later version.
00010 
00011    The GNU C Library is distributed in the hope that it will be useful,
00012    but WITHOUT ANY WARRANTY; without even the implied warranty of
00013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014    Lesser General Public License for more details.
00015 
00016    You should have received a copy of the GNU Lesser General Public
00017    License along with the GNU C Library; if not, write to the Free
00018    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00019    02111-1307 USA.  */
00020 
00021 #include <fenv.h>
00022 
00023 int
00024 feenableexcept (int excepts)
00025 {
00026   unsigned short int new_exc, old_exc;
00027   unsigned int new;
00028 
00029   excepts &= FE_ALL_EXCEPT;
00030 
00031   /* Get the current control word of the x87 FPU.  */
00032   __asm__ ("fstcw %0" : "=m" (*&new_exc));
00033 
00034   old_exc = (~new_exc) & FE_ALL_EXCEPT;
00035 
00036   new_exc &= ~excepts;
00037   __asm__ ("fldcw %0" : : "m" (*&new_exc));
00038 
00039   /* And now the same for the SSE MXCSR register.  */
00040   __asm__ ("stmxcsr %0" : "=m" (*&new));
00041 
00042   /* The SSE exception masks are shifted by 7 bits.  */
00043   new &= ~(excepts << 7);
00044   __asm__ ("ldmxcsr %0" : : "m" (*&new));
00045 
00046   return old_exc;
00047 }