mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-24 22:10:13 +00:00
137 lines
3.5 KiB
C
137 lines
3.5 KiB
C
/* Round to long int long double floating-point values.
|
|
IBM extended format long double version.
|
|
Copyright (C) 2006-2020 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 <math.h>
|
|
#include <fenv.h>
|
|
#include <math_private.h>
|
|
#include <math_ldbl_opt.h>
|
|
#include <float.h>
|
|
#include <ieee754.h>
|
|
|
|
long
|
|
__lroundl (long double x)
|
|
{
|
|
double xh, xl;
|
|
long res, hi, lo;
|
|
|
|
ldbl_unpack (x, &xh, &xl);
|
|
|
|
/* Limit the range of values handled by the conversion to long.
|
|
We do this because we aren't sure whether that conversion properly
|
|
raises FE_INVALID. */
|
|
if (
|
|
#if __LONG_MAX__ == 2147483647
|
|
__builtin_expect
|
|
((__builtin_fabs (xh) <= (double) __LONG_MAX__ + 2), 1)
|
|
#else
|
|
__builtin_expect
|
|
((__builtin_fabs (xh) <= -(double) (-__LONG_MAX__ - 1)), 1)
|
|
#endif
|
|
#if !defined (FE_INVALID)
|
|
|| 1
|
|
#endif
|
|
)
|
|
{
|
|
#if __LONG_MAX__ == 2147483647
|
|
long long llhi = (long long) xh;
|
|
if (llhi != (long) llhi)
|
|
hi = llhi < 0 ? -__LONG_MAX__ - 1 : __LONG_MAX__;
|
|
else
|
|
hi = llhi;
|
|
xh -= hi;
|
|
#else
|
|
if (__glibc_unlikely ((xh == -(double) (-__LONG_MAX__ - 1))))
|
|
{
|
|
/* When XH is 9223372036854775808.0, converting to long long will
|
|
overflow, resulting in an invalid operation. However, XL might
|
|
be negative and of sufficient magnitude that the overall long
|
|
double is in fact in range. Avoid raising an exception. In any
|
|
case we need to convert this value specially, because
|
|
the converted value is not exactly represented as a double
|
|
thus subtracting HI from XH suffers rounding error. */
|
|
hi = __LONG_MAX__;
|
|
xh = 1.0;
|
|
}
|
|
else
|
|
{
|
|
hi = (long) xh;
|
|
xh -= hi;
|
|
}
|
|
#endif
|
|
ldbl_canonicalize (&xh, &xl);
|
|
|
|
lo = (long) xh;
|
|
|
|
/* Peg at max/min values, assuming that the above conversions do so.
|
|
Strictly speaking, we can return anything for values that overflow,
|
|
but this is more useful. */
|
|
res = (long int) ((unsigned long int) hi + (unsigned long int) lo);
|
|
|
|
/* This is just sign(hi) == sign(lo) && sign(res) != sign(hi). */
|
|
if (__glibc_unlikely (((~(hi ^ lo) & (res ^ hi)) < 0)))
|
|
goto overflow;
|
|
|
|
xh -= lo;
|
|
ldbl_canonicalize (&xh, &xl);
|
|
|
|
hi = res;
|
|
if (xh > 0.5)
|
|
{
|
|
res += 1UL;
|
|
}
|
|
else if (xh == 0.5)
|
|
{
|
|
if (xl > 0.0 || (xl == 0.0 && res >= 0))
|
|
res += 1UL;
|
|
}
|
|
else if (-xh > 0.5)
|
|
{
|
|
res -= 1UL;
|
|
}
|
|
else if (-xh == 0.5)
|
|
{
|
|
if (xl < 0.0 || (xl == 0.0 && res <= 0))
|
|
res -= 1UL;
|
|
}
|
|
|
|
if (__glibc_unlikely (((~(hi ^ (res - hi)) & (res ^ hi)) < 0)))
|
|
goto overflow;
|
|
|
|
return res;
|
|
}
|
|
else
|
|
{
|
|
if (xh > 0.0)
|
|
hi = __LONG_MAX__;
|
|
else if (xh < 0.0)
|
|
hi = -__LONG_MAX__ - 1;
|
|
else
|
|
/* Nan */
|
|
hi = 0;
|
|
}
|
|
|
|
overflow:
|
|
#ifdef FE_INVALID
|
|
feraiseexcept (FE_INVALID);
|
|
#endif
|
|
return hi;
|
|
}
|
|
|
|
long_double_symbol (libm, __lroundl, lroundl);
|