Back to index

glibc  2.9
feholdexcpt.c
Go to the documentation of this file.
00001 /* Store current floating-point environment and clear exceptions.
00002    Copyright (C) 2000 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004    Contributed by David Huggins-Daines <dhd@debian.org>, 2000
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 #include <string.h>
00023 
00024 int
00025 feholdexcept (fenv_t *envp)
00026 {
00027   union { unsigned long long buf[4]; fenv_t env; } clear;
00028   unsigned long long *bufptr;
00029 
00030   /* Store the environment.  */
00031   bufptr = clear.buf;
00032   __asm__ (
00033           "fstd,ma %%fr0,8(%1)\n"
00034           : "=m" (clear), "+r" (bufptr) : : "%r0");
00035   memcpy (envp, &clear.env, sizeof (fenv_t));
00036 
00037   /* Clear exception queues */
00038   memset (clear.env.__exception, 0, sizeof (clear.env.__exception));
00039   /* And set all exceptions to non-stop.  */
00040   clear.env.__status_word &= ~FE_ALL_EXCEPT;
00041   /* Now clear all flags  */
00042   clear.env.__status_word &= ~(FE_ALL_EXCEPT << 27);
00043 
00044   /* Load the new environment. Note: fr0 must load last to enable T-bit 
00045      Thus we start bufptr at the end and work backwards */
00046   bufptr = (unsigned int)(clear.buf) + sizeof(unsigned int)*4;
00047   __asm__ (
00048           "fldd,mb -8(%0),%%fr0\n"
00049           : : "r" (bufptr), "m" (clear) : "%r0");
00050 
00051   return 0;
00052 }
00053 
00054 libm_hidden_def (feholdexcept)
00055