mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-25 04:01:10 +00:00
80 lines
1.9 KiB
C
80 lines
1.9 KiB
C
/* Software floating-point emulation.
|
|
ilogbl(x, exp)
|
|
Copyright (C) 1999-2014 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Jakub Jelinek (jj@ultra.linux.cz).
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
/* ilogbl(long double x)
|
|
* return the binary exponent of non-zero x
|
|
* ilogbl(0) = 0x80000001
|
|
* ilogbl(inf/NaN) = 0x7fffffff (no signal is raised)
|
|
*/
|
|
|
|
#include "soft-fp.h"
|
|
#include "quad.h"
|
|
#include <math.h>
|
|
|
|
int __ieee754_ilogbl (long double x)
|
|
{
|
|
FP_DECL_EX;
|
|
FP_DECL_Q(X);
|
|
|
|
/*
|
|
FP_UNPACK_Q(X, x);
|
|
switch (X_c)
|
|
{
|
|
case FP_CLS_ZERO:
|
|
return FP_ILOGB0;
|
|
case FP_CLS_NAN:
|
|
case FP_CLS_INF:
|
|
return FP_ILOGBNAN;
|
|
default:
|
|
return X_e;
|
|
}
|
|
*/
|
|
FP_UNPACK_RAW_Q(X, x);
|
|
switch (X_e)
|
|
{
|
|
default:
|
|
return X_e - _FP_EXPBIAS_Q;
|
|
case 0:
|
|
#if (2 * _FP_W_TYPE_SIZE) < _FP_FRACBITS_Q
|
|
if (_FP_FRAC_ZEROP_4(X))
|
|
return FP_ILOGB0;
|
|
else
|
|
{
|
|
_FP_I_TYPE shift;
|
|
_FP_FRAC_CLZ_4(shift, X);
|
|
shift -= _FP_FRACXBITS_Q;
|
|
return X_e - _FP_EXPBIAS_Q - 1 + shift;
|
|
}
|
|
#else
|
|
if (_FP_FRAC_ZEROP_2(X))
|
|
return FP_ILOGB0;
|
|
else
|
|
{
|
|
_FP_I_TYPE shift;
|
|
_FP_FRAC_CLZ_2(shift, X);
|
|
shift -= _FP_FRACXBITS_Q;
|
|
return X_e - _FP_EXPBIAS_Q - 1 + shift;
|
|
}
|
|
#endif
|
|
case _FP_EXPBIAS_Q:
|
|
return FP_ILOGBNAN;
|
|
}
|
|
}
|