glibc/sysdeps/ieee754/dbl-64/s_llround.c

85 lines
2.2 KiB
C

/* Round double value to long long int.
Copyright (C) 1997-2023 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/>. */
#define lround __hidden_lround
#define __lround __hidden___lround
#include <fenv.h>
#include <limits.h>
#include <math.h>
#include <sysdep.h>
#include <math_private.h>
#include <libm-alias-double.h>
#include <fix-fp-int-convert-overflow.h>
long long int
__llround (double x)
{
int32_t j0;
int64_t i0;
long long int result;
int sign;
EXTRACT_WORDS64 (i0, x);
j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
sign = i0 < 0 ? -1 : 1;
i0 &= UINT64_C(0xfffffffffffff);
i0 |= UINT64_C(0x10000000000000);
if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
{
if (j0 < 0)
return j0 < -1 ? 0 : sign;
else if (j0 >= 52)
result = i0 << (j0 - 52);
else
{
i0 += UINT64_C(0x8000000000000) >> j0;
result = i0 >> (52 - j0);
}
}
else
{
#ifdef FE_INVALID
/* The number is too large. Unless it rounds to LLONG_MIN,
FE_INVALID must be raised and the return value is
unspecified. */
if (FIX_DBL_LLONG_CONVERT_OVERFLOW && x != (double) LLONG_MIN)
{
feraiseexcept (FE_INVALID);
return sign == 1 ? LLONG_MAX : LLONG_MIN;
}
#endif
return (long long int) x;
}
return sign * result;
}
libm_alias_double (__llround, llround)
/* long has the same width as long long on LP64 machines, so use an alias. */
#undef lround
#undef __lround
#ifdef _LP64
strong_alias (__llround, __lround)
libm_alias_double (__lround, lround)
#endif