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/* Round argument to nearest integral value according to current rounding
direction.
Copyright (C) 1997-2024 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 <fenv.h>
#include <limits.h>
#include <math.h>
#include <math-narrow-eval.h>
#include <math_private.h>
#include <libm-alias-double.h>
#include <fix-fp-int-convert-overflow.h>
#include <math-use-builtins.h>
long int
__lrint (double x)
{
#if USE_LRINT_BUILTIN
return __builtin_lrint (x);
#else
/* Use generic implementation. */
static const double two52[2] =
{
4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
-4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
};
int32_t j0;
uint32_t i0, i1;
double w;
double t;
long int result;
int sx;
EXTRACT_WORDS (i0, i1, x);
j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
sx = i0 >> 31;
i0 &= 0xfffff;
i0 |= 0x100000;
if (j0 < 20)
{
w = math_narrow_eval (two52[sx] + x);
t = w - two52[sx];
EXTRACT_WORDS (i0, i1, t);
j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
i0 &= 0xfffff;
i0 |= 0x100000;
result = (j0 < 0 ? 0 : i0 >> (20 - j0));
}
else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
{
if (j0 >= 52)
result = ((long int) i0 << (j0 - 20)) | ((long int) i1 << (j0 - 52));
else
{
#if defined FE_INVALID || defined FE_INEXACT
/* X < LONG_MAX + 1 implied by J0 < 31. */
if (sizeof (long int) == 4
&& x > (double) LONG_MAX)
{
/* In the event of overflow we must raise the "invalid"
exception, but not "inexact". */
t = __nearbyint (x);
feraiseexcept (t == LONG_MAX ? FE_INEXACT : FE_INVALID);
}
else
#endif
{
w = math_narrow_eval (two52[sx] + x);
t = w - two52[sx];
}
EXTRACT_WORDS (i0, i1, t);
j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
i0 &= 0xfffff;
i0 |= 0x100000;
if (j0 == 20)
result = (long int) i0;
else
result = ((long int) i0 << (j0 - 20)) | (i1 >> (52 - j0));
}
}
else
{
/* The number is too large. Unless it rounds to LONG_MIN,
FE_INVALID must be raised and the return value is
unspecified. */
#if defined FE_INVALID || defined FE_INEXACT
if (sizeof (long int) == 4
&& x < (double) LONG_MIN
&& x > (double) LONG_MIN - 1.0)
{
/* If truncation produces LONG_MIN, the cast will not raise
the exception, but may raise "inexact". */
t = __nearbyint (x);
feraiseexcept (t == LONG_MIN ? FE_INEXACT : FE_INVALID);
return LONG_MIN;
}
else if (FIX_DBL_LONG_CONVERT_OVERFLOW && x != (double) LONG_MIN)
{
feraiseexcept (FE_INVALID);
return sx == 0 ? LONG_MAX : LONG_MIN;
}
#endif
return (long int) x;
}
return sx ? -result : result;
#endif /* ! USE_LRINT_BUILTIN */
}
libm_alias_double (__lrint, lrint)
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