[unix-history] / .ref-BSD-4_3_Net_2 / usr / src / lib / libm / common_source / floor.c

/*
 * Copyright (c) 1985 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


double ceil();
double floor();

/*
 * 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(x)
double x;
{
	double y;

	if (
#if !defined(vax)&&!defined(tahoe)
		x != x ||	/* NaN */
#endif	/* !defined(vax)&&!defined(tahoe) */
		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(x)
double x;
{
	double y;

	if (
#if !defined(vax)&&!defined(tahoe)
		x != x ||	/* NaN */
#endif	/* !defined(vax)&&!defined(tahoe) */
		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;
	}
}

#ifndef national			/* rint() is in ./NATIONAL/support.s */
/*
 * 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);
}
#endif	/* not national */
Commit	Line	Data
b6be2d90 KB	1	/*
b6be2d90 KB	2	* Copyright (c) 1985 Regents of the University of California.
e2481ef1 KB	3	* All rights reserved.
e2481ef1 KB	4	*
af359dea C	5	* Redistribution and use in source and binary forms, with or without
	6	* modification, are permitted provided that the following conditions
	7	* are met:
	8	* 1. Redistributions of source code must retain the above copyright
	9	* notice, this list of conditions and the following disclaimer.
	10	* 2. Redistributions in binary form must reproduce the above copyright
	11	* notice, this list of conditions and the following disclaimer in the
	12	* documentation and/or other materials provided with the distribution.
	13	* 3. All advertising materials mentioning features or use of this software
	14	* must display the following acknowledgement:
	15	* This product includes software developed by the University of
	16	* California, Berkeley and its contributors.
	17	* 4. Neither the name of the University nor the names of its contributors
	18	* may be used to endorse or promote products derived from this software
	19	* without specific prior written permission.
e2481ef1	20	*
af359dea C	21	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	22	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	23	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	24	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	25	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	26	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	27	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	28	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	29	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	30	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	31	* SUCH DAMAGE.
b6be2d90 KB	32	*/
	33
	34	#ifndef lint
af359dea	35	static char sccsid[] = "@(#)floor.c 5.7 (Berkeley) 10/9/90";
b6be2d90	36	#endif /* not lint */
2db37043	37
9eda3584 KB	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	double ceil();
	50	double floor();
e2481ef1	51
2db37043	52	/*
e2481ef1 KB	53	* floor(x) := the largest integer no larger than x;
	54	* ceil(x) := -floor(-x), for all real x.
	55	*
	56	* Note: Inexact will be signaled if x is not an integer, as is
	57	* customary for IEEE 754. No other signal can be emitted.
2db37043	58	*/
2db37043	59	double
e2481ef1 KB	60	floor(x)
e2481ef1 KB	61	double x;
2db37043	62	{
9eda3584	63	double y;
2db37043	64
e2481ef1 KB	65	if (
	66	#if !defined(vax)&&!defined(tahoe)
	67	x != x \|\| /* NaN */
	68	#endif /* !defined(vax)&&!defined(tahoe) */
	69	x >= L) /* already an even integer */
	70	return x;
	71	else if (x < (double)0)
	72	return -ceil(-x);
	73	else { /* now 0 <= x < L */
	74	y = L+x; /* destructive store must be forced */
	75	y -= L; /* an integer, and \|x-y\| < 1 */
	76	return x < y ? y-(double)1 : y;
	77	}
2db37043 ZAL	78	}
	79
	80	double
e2481ef1 KB	81	ceil(x)
e2481ef1 KB	82	double x;
2db37043	83	{
9eda3584	84	double y;
e2481ef1 KB	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	}
2db37043 ZAL	99	}
2db37043 ZAL	100
859dc438	101	#ifndef national /* rint() is in ./NATIONAL/support.s */
2db37043 ZAL	102	/*
	103	* algorithm for rint(x) in pseudo-pascal form ...
	104	*
	105	* real rint(x): real x;
	106	* ... delivers integer nearest x in direction of prevailing rounding
	107	* ... mode
	108	* const L = (last consecutive integer)/2
	109	* = 2**55; for VAX D
	110	* = 2**52; for IEEE 754 Double
	111	* real s,t;
	112	* begin
	113	* if x != x then return x; ... NaN
	114	* if \|x\| >= L then return x; ... already an integer
	115	* s := copysign(L,x);
	116	* t := x + s; ... = (x+s) rounded to integer
	117	* return t - s
	118	* end;
	119	*
	120	* Note: Inexact will be signaled if x is not an integer, as is
	121	* customary for IEEE 754. No other signal can be emitted.
	122	*/
2db37043 ZAL	123	double
	124	rint(x)
	125	double x;
	126	{
9eda3584 KB	127	double s,t;
	128	const double one = 1.0;
	129
859dc438	130	#if !defined(vax)&&!defined(tahoe)
2db37043 ZAL	131	if (x != x) /* NaN */
2db37043 ZAL	132	return (x);
859dc438	133	#endif /* !defined(vax)&&!defined(tahoe) */
2db37043 ZAL	134	if (copysign(x,one) >= L) /* already an integer */
	135	return (x);
	136	s = copysign(L,x);
	137	t = x + s; /* x+s rounded to integer */
	138	return (t - s);
	139	}
859dc438	140	#endif /* not national */