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