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n_floor.c revision 1.6 
      1 /*      $NetBSD: n_floor.c,v 1.6 2004/05/13 20:35:40 mhitch Exp $ */
      2 /*
      3  * Copyright (c) 1985, 1993
      4  *	The Regents of the University of California.  All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  * 3. Neither the name of the University nor the names of its contributors
     15  *    may be used to endorse or promote products derived from this software
     16  *    without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     28  * SUCH DAMAGE.
     29  */
     30 
     31 #ifndef lint
     32 #if 0
     33 static char sccsid[] = "@(#)floor.c	8.1 (Berkeley) 6/4/93";
     34 #endif
     35 #endif /* not lint */
     36 
     37 #define _LIBM_STATIC
     38 #include "mathimpl.h"
     39 
     40 vc(L, 4503599627370496.0E0 ,0000,5c00,0000,0000, 55, 1.0) /* 2**55 */
     41 
     42 ic(L, 4503599627370496.0E0, 52, 1.0)			  /* 2**52 */
     43 
     44 #ifdef vccast
     45 #define	L	vccast(L)
     46 #endif
     47 
     48 /*
     49  * floor(x) := the largest integer no larger than x;
     50  * ceil(x) := -floor(-x), for all real x.
     51  *
     52  * Note: Inexact will be signaled if x is not an integer, as is
     53  *	customary for IEEE 754.  No other signal can be emitted.
     54  */
     55 double
     56 floor(double x)
     57 {
     58 	volatile double y;
     59 
     60 	if (
     61 #if !defined(__vax__)&&!defined(tahoe)
     62 		x != x ||	/* NaN */
     63 #endif	/* !defined(__vax__)&&!defined(tahoe) */
     64 		x >= L)		/* already an even integer */
     65 		return x;
     66 	else if (x < (double)0)
     67 		return -ceil(-x);
     68 	else {			/* now 0 <= x < L */
     69 		y = L+x;		/* destructive store must be forced */
     70 		y -= L;			/* an integer, and |x-y| < 1 */
     71 		return x < y ? y-(double)1 : y;
     72 	}
     73 }
     74 
     75 float
     76 floorf(float x)
     77 {
     78 	return floor((double)x);
     79 }
     80 
     81 double
     82 ceil(double x)
     83 {
     84 	volatile double y;
     85 
     86 	if (
     87 #if !defined(__vax__)&&!defined(tahoe)
     88 		x != x ||	/* NaN */
     89 #endif	/* !defined(__vax__)&&!defined(tahoe) */
     90 		x >= L)		/* already an even integer */
     91 		return x;
     92 	else if (x < (double)0)
     93 		return -floor(-x);
     94 	else {			/* now 0 <= x < L */
     95 		y = L+x;		/* destructive store must be forced */
     96 		y -= L;			/* an integer, and |x-y| < 1 */
     97 		return x > y ? y+(double)1 : y;
     98 	}
     99 }
    100 
    101 float
    102 ceilf(float x)
    103 {
    104 	return ceil((double)x);
    105 }
    106 
    107 #ifndef ns32000			/* rint() is in ./NATIONAL/support.s */
    108 /*
    109  * algorithm for rint(x) in pseudo-pascal form ...
    110  *
    111  * real rint(x): real x;
    112  *	... delivers integer nearest x in direction of prevailing rounding
    113  *	... mode
    114  * const	L = (last consecutive integer)/2
    115  * 	  = 2**55; for VAX D
    116  * 	  = 2**52; for IEEE 754 Double
    117  * real	s,t;
    118  * begin
    119  * 	if x != x then return x;		... NaN
    120  * 	if |x| >= L then return x;		... already an integer
    121  * 	s := copysign(L,x);
    122  * 	t := x + s;				... = (x+s) rounded to integer
    123  * 	return t - s
    124  * end;
    125  *
    126  * Note: Inexact will be signaled if x is not an integer, as is
    127  *	customary for IEEE 754.  No other signal can be emitted.
    128  */
    129 double
    130 rint(double x)
    131 {
    132 	double s;
    133 	volatile double t;
    134 	const double one = 1.0;
    135 
    136 #if !defined(__vax__)&&!defined(tahoe)
    137 	if (x != x)				/* NaN */
    138 		return (x);
    139 #endif	/* !defined(__vax__)&&!defined(tahoe) */
    140 	if (copysign(x,one) >= L)		/* already an integer */
    141 	    return (x);
    142 	s = copysign(L,x);
    143 	t = x + s;				/* x+s rounded to integer */
    144 	return (t - s);
    145 }
    146 #endif	/* not national */
    147