s_lrint.c (2049B)
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 30 #ifndef type 31 #define type double 32 #define roundit rint 33 #define dtype long 34 #define fn lrint 35 #endif 36 37 /* 38 * C99 says we should not raise a spurious inexact exception when an 39 * invalid exception is raised. Unfortunately, the set of inputs 40 * that overflows depends on the rounding mode when 'dtype' has more 41 * significant bits than 'type'. Hence, we bend over backwards for the 42 * sake of correctness; an MD implementation could be more efficient. 43 */ 44 dtype 45 fn(type x) 46 { 47 fenv_t env; 48 dtype d; 49 50 feholdexcept(&env); 51 d = (dtype)roundit(x); 52 if (fetestexcept(FE_INVALID)) 53 feclearexcept(FE_INEXACT); 54 feupdateenv(&env); 55 return (d); 56 }