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/*-
* Copyright (c) 2008 David Schultz <das@FreeBSD.ORG>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <float.h>
#include <math.h>
#include "fpmath.h"
#define BIAS (LDBL_MAX_EXP - 1)
static const float
shift[2] = {
#if LDBL_MANT_DIG == 64
0x1.0p63, -0x1.0p63
#elif LDBL_MANT_DIG == 113
0x1.0p112, -0x1.0p112
#else
#error "Unsupported long double format"
#endif
};
long double
rintl(long double x)
{
union IEEEl2bits u;
short sign;
u.e = x;
if (u.bits.exp >= BIAS + LDBL_MANT_DIG - 1) {
/*
* The biased exponent is greater than the number of digits
* in the mantissa, so x is inf, NaN, or an integer.
*/
return (x);
}
sign = u.bits.sign;
/*
* The following code assumes that intermediate results are
* evaluated in long double precision. If they are evaluated in
* greater precision, double rounding may occur, and if they are
* evaluated in less precision (as on i386), results will be
* wildly incorrect.
*/
x += shift[sign];
x -= shift[sign];
/*
* If the result is +-0, then it must have the same sign as x, but
* the above calculation doesn't always give this. Fix up the sign.
*/
if (x == 0.0L)
return (sign ? -0.0L : 0.0L);
return (x);
}
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