| 1 | /* |
| 2 | * Copyright (c) 1985 Regents of the University of California. |
| 3 | * All rights reserved. |
| 4 | * |
| 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. |
| 20 | * |
| 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. |
| 32 | */ |
| 33 | |
| 34 | #ifndef lint |
| 35 | static char sccsid[] = "@(#)floor.c 5.7 (Berkeley) 10/9/90"; |
| 36 | #endif /* not lint */ |
| 37 | |
| 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(); |
| 51 | |
| 52 | /* |
| 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. |
| 58 | */ |
| 59 | double |
| 60 | floor(x) |
| 61 | double x; |
| 62 | { |
| 63 | double y; |
| 64 | |
| 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 | } |
| 78 | } |
| 79 | |
| 80 | double |
| 81 | ceil(x) |
| 82 | double x; |
| 83 | { |
| 84 | 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 | #ifndef national /* rint() is in ./NATIONAL/support.s */ |
| 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 | */ |
| 123 | double |
| 124 | rint(x) |
| 125 | double x; |
| 126 | { |
| 127 | double s,t; |
| 128 | const double one = 1.0; |
| 129 | |
| 130 | #if !defined(vax)&&!defined(tahoe) |
| 131 | if (x != x) /* NaN */ |
| 132 | return (x); |
| 133 | #endif /* !defined(vax)&&!defined(tahoe) */ |
| 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 | } |
| 140 | #endif /* not national */ |