mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-25 22:40:05 +00:00
88 lines
3.1 KiB
C
88 lines
3.1 KiB
C
/* snarfed from BSD common_source/floor.c:
|
|
* Copyright (c) 1985, 1995 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. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* 4. 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.
|
|
*/
|
|
|
|
#ifndef lint
|
|
static char sccsid[] = "@(#)floor.c 5.7 (Berkeley) 10/9/90";
|
|
#endif /* not lint */
|
|
|
|
#include "mathimpl.h"
|
|
|
|
vc(L, 4503599627370496.0E0 ,0000,5c00,0000,0000, 55, 1.0) /* 2**55 */
|
|
|
|
ic(L, 4503599627370496.0E0, 52, 1.0) /* 2**52 */
|
|
|
|
#ifdef vccast
|
|
#define L vccast(L)
|
|
#endif
|
|
|
|
/*
|
|
* 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 x != 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(x)
|
|
double x;
|
|
{
|
|
double s,t;
|
|
const double one = 1.0;
|
|
|
|
#if !defined(vax)&&!defined(tahoe)
|
|
if (x != x) /* NaN */
|
|
return (x);
|
|
#endif /* !defined(vax)&&!defined(tahoe) */
|
|
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);
|
|
}
|
|
|
|
weak_alias (__rint, rint)
|