sysdeps/sparc/sparc64/soft-fp/e_ilogbl.c

   1 /* Software floating-point emulation.
   2    ilogbl(x, exp)
   3    Copyright (C) 1999-2014 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Jakub Jelinek (jj@ultra.linux.cz).
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21 /* ilogbl(long double x)
  22  * return the binary exponent of non-zero x
  23  * ilogbl(0) = 0x80000001
  24  * ilogbl(inf/NaN) = 0x7fffffff (no signal is raised)
  25  */
  26
  27 #include "soft-fp.h"
  28 #include "quad.h"
  29 #include <math.h>
  30
  31 int __ieee754_ilogbl (long double x)
  32 {
  33   FP_DECL_EX;
  34   FP_DECL_Q(X);
  35
  36 /*
  37   FP_UNPACK_Q(X, x);
  38   switch (X_c)
  39     {
  40     case FP_CLS_ZERO:
  41       return FP_ILOGB0;
  42     case FP_CLS_NAN:
  43     case FP_CLS_INF:
  44       return FP_ILOGBNAN;
  45     default:
  46       return X_e;
  47     }
  48  */
  49   FP_UNPACK_RAW_Q(X, x);
  50   switch (X_e)
  51     {
  52     default:
  53       return X_e - _FP_EXPBIAS_Q;
  54     case 0:
  55 #if (2 * _FP_W_TYPE_SIZE) < _FP_FRACBITS_Q
  56       if (_FP_FRAC_ZEROP_4(X))
  57         return FP_ILOGB0;
  58       else
  59         {
  60           _FP_I_TYPE shift;
  61           _FP_FRAC_CLZ_4(shift, X);
  62           shift -= _FP_FRACXBITS_Q;
  63           return X_e - _FP_EXPBIAS_Q - 1 + shift;
  64         }
  65 #else
  66       if (_FP_FRAC_ZEROP_2(X))
  67         return FP_ILOGB0;
  68       else
  69         {
  70           _FP_I_TYPE shift;
  71           _FP_FRAC_CLZ_2(shift, X);
  72           shift -= _FP_FRACXBITS_Q;
  73           return X_e - _FP_EXPBIAS_Q - 1 + shift;
  74         }
  75 #endif
  76     case _FP_EXPBIAS_Q:
  77       return FP_ILOGBNAN;
  78     }
  79 }