mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-22 04:50:07 +00:00
66 lines
1.9 KiB
C
66 lines
1.9 KiB
C
|
/* Return exp2(X) - 1.
|
||
|
|
Copyright (C) 2024 Free Software Foundation, Inc.
|
||
|
|
This file is part of the GNU C Library.
|
||
|
|
|
||
|
|
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
|
||
|
|
<https://www.gnu.org/licenses/>. */
|
||
|
|
|
||
|
|
#include <errno.h>
|
||
|
|
#include <fenv.h>
|
||
|
|
#include <math.h>
|
||
|
|
#include <math_private.h>
|
||
|
|
#include <math-underflow.h>
|
||
|
|
|
||
|
|
FLOAT
|
||
|
|
M_DECL_FUNC (__exp2m1) (FLOAT x)
|
||
|
|
{
|
||
|
|
if (isgreaterequal (x, M_LIT (-1.0)) && islessequal (x, M_LIT (1.0)))
|
||
|
|
{
|
||
|
|
FLOAT ret = M_SUF (__expm1) (M_MLIT (M_LN2) * x);
|
||
|
|
math_check_force_underflow (ret);
|
||
|
|
if (x != 0 && ret == 0)
|
||
|
|
__set_errno (ERANGE);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
else if (isgreater (x, M_MANT_DIG + M_LIT (2.0)))
|
||
|
|
{
|
||
|
|
#if defined FE_DOWNWARD || defined FE_TOWARDZERO
|
||
|
|
/* exp2m1 (MAX_EXP) should not overflow in these two rounding
|
||
|
|
modes, but exp2 does overflow. */
|
||
|
|
if (x == M_MAX_EXP)
|
||
|
|
{
|
||
|
|
int rnd_mode = fegetround ();
|
||
|
|
if (0
|
||
|
|
# ifdef FE_DOWNWARD
|
||
|
|
|| rnd_mode == FE_DOWNWARD
|
||
|
|
# endif
|
||
|
|
# ifdef FE_TOWARDZERO
|
||
|
|
|| rnd_mode == FE_TOWARDZERO
|
||
|
|
# endif
|
||
|
|
)
|
||
|
|
return M_MAX;
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
FLOAT ret = M_SUF (__ieee754_exp2) (x);
|
||
|
|
if (!isfinite (ret) && isfinite (x))
|
||
|
|
__set_errno (ERANGE);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
else if (isless (x, -M_MANT_DIG - M_LIT (2.0)))
|
||
|
|
return M_LIT (-1.0);
|
||
|
|
else
|
||
|
|
return M_SUF (__ieee754_exp2) (x) - M_LIT (1.0);
|
||
|
|
}
|
||
|
|
declare_mgen_alias (__exp2m1, exp2m1);
|