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/* $OpenBSD: n_floor.c,v 1.14 2011/05/30 18:34:38 martynas Exp $ */
/* $NetBSD: n_floor.c,v 1.1 1995/10/10 23:36:48 ragge Exp $ */
/*
* Copyright (c) 1985, 1993
* The Regents of the University of California. 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.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*/
/* LINTLIBRARY */
#include <sys/cdefs.h>
#include <math.h>
#include "mathimpl.h"
static const double L = 36028797018963968.0E0;
/*
* floor(x) := the largest integer no larger than x;
* ceil(x) := -floor(-x), for all real x.
*
* Note: Inexact will be signaled if x is not an integer, as is
* customary for IEEE 754. No other signal can be emitted.
*/
double
floor(double x)
{
volatile double y;
if (isnan(x) || x >= L) /* already an even integer */
return x;
else if (x < (double)0)
return -ceil(-x);
else { /* now 0 <= x < L */
y = L+x; /* destructive store must be forced */
y -= L; /* an integer, and |x-y| < 1 */
return x < y ? y-(double)1 : y;
}
}
double
ceil(double x)
{
volatile double y;
if (isnan(x) || x >= L) /* already an even integer */
return x;
else if (x < (double)0)
return -floor(-x);
else { /* now 0 <= x < L */
y = L+x; /* destructive store must be forced */
y -= L; /* an integer, and |x-y| < 1 */
return x > y ? y+(double)1 : y;
}
}
/*
* algorithm for rint(x) in pseudo-pascal form ...
*
* real rint(x): real x;
* ... delivers integer nearest x in direction of prevailing rounding
* ... mode
* const L = (last consecutive integer)/2
* = 2**55; for VAX D
* = 2**52; for IEEE 754 Double
* real s,t;
* begin
* if isnan(x) then return x; ... NaN
* if |x| >= L then return x; ... already an integer
* s := copysign(L,x);
* t := x + s; ... = (x+s) rounded to integer
* return t - s
* end;
*
* Note: Inexact will be signaled if x is not an integer, as is
* customary for IEEE 754. No other signal can be emitted.
*/
double
rint(double x)
{
double s;
volatile double t;
const double one = 1.0;
if (isnan(x))
return (x);
if (copysign(x, one) >= L) /* already an integer */
return (x);
s = copysign(L,x);
t = x + s; /* x+s rounded to integer */
return (t - s);
}
#ifdef lint
/* PROTOLIB1 */
long double rintl(long double);
#else /* lint */
__weak_alias(rintl, rint);
#endif /* lint */
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