glibc/sysdeps/ieee754/flt-32/s_lrintf.c

87 lines
2.1 KiB
C

/* Round argument to nearest integral value according to current rounding
direction.
Copyright (C) 1997-2017 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 <fix-fp-int-convert-overflow.h>
static const float two23[2] =
{
8.3886080000e+06, /* 0x4B000000 */
-8.3886080000e+06, /* 0xCB000000 */
};
long int
__lrintf (float x)
{
int32_t j0;
u_int32_t i0;
float w;
float t;
long int result;
int sx;
GET_FLOAT_WORD (i0, x);
sx = i0 >> 31;
j0 = ((i0 >> 23) & 0xff) - 0x7f;
i0 &= 0x7fffff;
i0 |= 0x800000;
if (j0 < (int32_t) (sizeof (long int) * 8) - 1)
{
if (j0 >= 23)
result = (long int) i0 << (j0 - 23);
else
{
w = math_narrow_eval (two23[sx] + x);
t = w - two23[sx];
GET_FLOAT_WORD (i0, t);
j0 = ((i0 >> 23) & 0xff) - 0x7f;
i0 &= 0x7fffff;
i0 |= 0x800000;
result = (j0 < 0 ? 0 : i0 >> (23 - j0));
}
}
else
{
#ifdef FE_INVALID
/* The number is too large. Unless it rounds to LONG_MIN,
FE_INVALID must be raised and the return value is
unspecified. */
if (FIX_FLT_LONG_CONVERT_OVERFLOW && x != (float) LONG_MIN)
{
feraiseexcept (FE_INVALID);
return sx == 0 ? LONG_MAX : LONG_MIN;
}
#endif
return (long int) x;
}
return sx ? -result : result;
}
weak_alias (__lrintf, lrintf)