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glibc  2.9
s_fpclassify.c
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00001 /* Return classification value corresponding to argument.
00002    Copyright (C) 1997, 2002 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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 <math.h>
00022 
00023 #include "math_private.h"
00024 
00025 
00026 int
00027 __fpclassify (double x)
00028 {
00029   u_int32_t hx, lx;
00030   int retval = FP_NORMAL;
00031 
00032   EXTRACT_WORDS (hx, lx, x);
00033   lx |= hx & 0xfffff;
00034   hx &= 0x7ff00000;
00035   if ((hx | lx) == 0)
00036     retval = FP_ZERO;
00037   else if (hx == 0)
00038     retval = FP_SUBNORMAL;
00039   else if (hx == 0x7ff00000)
00040     retval = lx != 0 ? FP_NAN : FP_INFINITE;
00041 
00042   return retval;
00043 }
00044 libm_hidden_def (__fpclassify)