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Diffstat (limited to 'sysdeps/generic/rint.c')
| -rw-r--r-- | sysdeps/generic/rint.c | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/sysdeps/generic/rint.c b/sysdeps/generic/rint.c new file mode 100644 index 0000000000..a26fd09620 --- /dev/null +++ b/sysdeps/generic/rint.c @@ -0,0 +1,87 @@ +/* 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) |