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glibc  2.9
s_ilogb.c
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00001 /* Copyright (C) 1996, 1997, 1999 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 #include "mathimpl.h"
00021 
00022 #ifndef SUFF
00023 #define SUFF
00024 #endif
00025 #ifndef float_type
00026 #define float_type double
00027 #endif
00028 
00029 #define CONCATX(a,b) __CONCAT(a,b)
00030 #define s(name) CONCATX(name,SUFF)
00031 #define m81(func) __m81_u(s(func))
00032 
00033 int
00034 s(__ilogb) (float_type x)
00035 {
00036   float_type result;
00037   unsigned long x_cond;
00038 
00039   x_cond = __m81_test (x);
00040   /* We must return consistent values for zero and NaN.  */
00041   if (x_cond & __M81_COND_ZERO)
00042     return FP_ILOGB0;
00043   if (x_cond & (__M81_COND_NAN | __M81_COND_INF))
00044     return FP_ILOGBNAN;
00045 
00046   __asm ("fgetexp%.x %1, %0" : "=f" (result) : "f" (x));
00047   return (int) result;
00048 }
00049 
00050 #define weak_aliasx(a,b) weak_alias(a,b)
00051 weak_aliasx (s(__ilogb), s(ilogb))