94 lines
2.8 KiB
C
94 lines
2.8 KiB
C
/*-
|
|
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
|
|
*
|
|
* 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 <stdint.h>
|
|
|
|
#include "fpmath.h"
|
|
|
|
#if LDBL_MAX_EXP != 0x4000
|
|
/* We also require the usual bias, min exp and expsign packing. */
|
|
#error "Unsupported long double format"
|
|
#endif
|
|
|
|
#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
|
|
};
|
|
static const float zero[2] = { 0.0, -0.0 };
|
|
|
|
long double
|
|
rintl(long double x)
|
|
{
|
|
union IEEEl2bits u;
|
|
uint32_t expsign;
|
|
int ex, sign;
|
|
|
|
u.e = x;
|
|
expsign = u.xbits.expsign;
|
|
ex = expsign & 0x7fff;
|
|
|
|
if (ex >= BIAS + LDBL_MANT_DIG - 1) {
|
|
if (ex == BIAS + LDBL_MAX_EXP)
|
|
return (x + x); /* Inf, NaN, or unsupported format */
|
|
return (x); /* finite and already an integer */
|
|
}
|
|
sign = expsign >> 15;
|
|
|
|
/*
|
|
* 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 (ex < BIAS && x == 0.0L)
|
|
return (zero[sign]);
|
|
|
|
return (x);
|
|
}
|