glibc/sysdeps/ieee754/ldbl-96/s_lroundl.c
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113 lines
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C

/* Round long double value to long int.
Copyright (C) 1997-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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/>. */
#include <fenv.h>
#include <limits.h>
#include <math.h>
#include <math_private.h>
#include <libm-alias-ldouble.h>
long int
__lroundl (long double x)
{
int32_t j0;
uint32_t se, i1, i0;
long int result;
int sign;
GET_LDOUBLE_WORDS (se, i0, i1, x);
j0 = (se & 0x7fff) - 0x3fff;
sign = (se & 0x8000) != 0 ? -1 : 1;
if (j0 < 31)
{
if (j0 < 0)
return j0 < -1 ? 0 : sign;
else
{
uint32_t j = i0 + (0x40000000 >> j0);
if (j < i0)
{
j >>= 1;
j |= 0x80000000;
++j0;
}
result = j >> (31 - j0);
#ifdef FE_INVALID
if (sizeof (long int) == 4
&& sign == 1
&& result == LONG_MIN)
/* Rounding brought the value out of range. */
feraiseexcept (FE_INVALID);
#endif
}
}
else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
{
if (j0 >= 63)
result = ((long int) i0 << (j0 - 31)) | (i1 << (j0 - 63));
else
{
uint32_t j = i1 + (0x80000000 >> (j0 - 31));
unsigned long int ures = i0;
if (j < i1)
++ures;
if (j0 == 31)
result = ures;
else
{
result = (ures << (j0 - 31)) | (j >> (63 - j0));
#ifdef FE_INVALID
if (sizeof (long int) == 8
&& sign == 1
&& result == LONG_MIN)
/* Rounding brought the value out of range. */
feraiseexcept (FE_INVALID);
#endif
}
}
}
else
{
/* The number is too large. Unless it rounds to LONG_MIN,
FE_INVALID must be raised and the return value is
unspecified. */
#ifdef FE_INVALID
if (sizeof (long int) == 4
&& x <= (long double) LONG_MIN - 0.5L)
{
/* If truncation produces LONG_MIN, the cast will not raise
the exception, but may raise "inexact". */
feraiseexcept (FE_INVALID);
return LONG_MIN;
}
#endif
return (long int) x;
}
return sign * result;
}
libm_alias_ldouble (__lround, lround)