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glibc  2.9
s_frexpl.c
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00001 /* Copyright (C) 2003 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #include <math.h>
00020 
00021 long double
00022 __frexpl (long double value, int *expptr)
00023 {
00024   long double mantissa, exponent;
00025   int iexponent;
00026   unsigned long fpsr;
00027 
00028   __asm ("ftst%.x %1\n"
00029         "fmove%.l %/fpsr, %0"
00030         : "=dm" (fpsr) : "f" (value));
00031   if (fpsr & (7 << 24))
00032     {
00033       /* Not finite or zero.  */
00034       *expptr = 0;
00035       return value;
00036     }
00037   __asm ("fgetexp%.x %1, %0" : "=f" (exponent) : "f" (value));
00038   iexponent = (int) exponent + 1;
00039   *expptr = iexponent;
00040   /* Unnormalized numbers must be handled specially, otherwise fscale
00041      results in overflow.  */
00042   if (iexponent <= -16384)
00043     {
00044       value *= 0x1p16383L;
00045       iexponent += 16383;
00046     }
00047   else if (iexponent >= 16384)
00048     {
00049       value *= 0x1p-16383L;
00050       iexponent -= 16383;
00051     }
00052 
00053   __asm ("fscale%.l %2, %0"
00054         : "=f" (mantissa)
00055         : "0" (value), "dmi" (-iexponent));
00056   return mantissa;
00057 }
00058 
00059 weak_alias (__frexpl, frexpl)