2 * Copyright (c) 1985, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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35 static char sccsid[] = "@(#)floor.c 8.1 (Berkeley) 6/4/93";
40 vc(L, 4503599627370496.0E0 ,0000,5c00,0000,0000, 55, 1.0) /* 2**55 */
42 ic(L, 4503599627370496.0E0, 52, 1.0) /* 2**52 */
49 * floor(x) := the largest integer no larger than x;
50 * ceil(x) := -floor(-x), for all real x.
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.
62 #if !defined(vax)&&!defined(tahoe)
64 #endif /* !defined(vax)&&!defined(tahoe) */
65 x >= L) /* already an even integer */
67 else if (x < (double)0)
69 else { /* now 0 <= x < L */
70 y = L+x; /* destructive store must be forced */
71 y -= L; /* an integer, and |x-y| < 1 */
72 return x < y ? y-(double)1 : y;
83 #if !defined(vax)&&!defined(tahoe)
85 #endif /* !defined(vax)&&!defined(tahoe) */
86 x >= L) /* already an even integer */
88 else if (x < (double)0)
90 else { /* now 0 <= x < L */
91 y = L+x; /* destructive store must be forced */
92 y -= L; /* an integer, and |x-y| < 1 */
93 return x > y ? y+(double)1 : y;
97 #ifndef ns32000 /* rint() is in ./NATIONAL/support.s */
99 * algorithm for rint(x) in pseudo-pascal form ...
101 * real rint(x): real x;
102 * ... delivers integer nearest x in direction of prevailing rounding
104 * const L = (last consecutive integer)/2
106 * = 2**52; for IEEE 754 Double
109 * if x != x then return x; ... NaN
110 * if |x| >= L then return x; ... already an integer
111 * s := copysign(L,x);
112 * t := x + s; ... = (x+s) rounded to integer
116 * Note: Inexact will be signaled if x is not an integer, as is
117 * customary for IEEE 754. No other signal can be emitted.
125 const double one = 1.0;
127 #if !defined(vax)&&!defined(tahoe)
128 if (x != x) /* NaN */
130 #endif /* !defined(vax)&&!defined(tahoe) */
131 if (copysign(x,one) >= L) /* already an integer */
134 t = x + s; /* x+s rounded to integer */
137 #endif /* not national */