s_lround.c (2452B)
1 /*- 2 * Copyright (c) 2005 David Schultz <das@FreeBSD.ORG> 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 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <fenv.h> 28 #include <math.h> 29 #include <limits.h> 30 31 #ifndef type 32 #define type double 33 #define roundit round 34 #define dtype long 35 #define DTYPE_MIN LONG_MIN 36 #define DTYPE_MAX LONG_MAX 37 #define fn lround 38 #endif 39 40 /* 41 * If type has more precision than dtype, the endpoints dtype_(min|max) are 42 * of the form xxx.5; they are "out of range" because lround() rounds away 43 * from 0. On the other hand, if type has less precision than dtype, then 44 * all values that are out of range are integral, so we might as well assume 45 * that everything is in range. (The correct condition in this case is 46 * harder to express.) At compile time, INRANGE(x) should reduce to two 47 * floating-point comparisons in the former case, or TRUE otherwise. 48 */ 49 static const double dtype_min = DTYPE_MIN - 0.5; 50 static const double dtype_max = DTYPE_MAX + 0.5; 51 #define INRANGE(x) (dtype_max - DTYPE_MAX != 0.5 || \ 52 ((x) > dtype_min && (x) < dtype_max)) 53 54 dtype 55 fn(type x) 56 { 57 58 if (INRANGE(x)) { 59 x = roundit(x); 60 return ((dtype)x); 61 } else { 62 feraiseexcept(FE_INVALID); 63 return (DTYPE_MAX); 64 } 65 }