newlib/libm/ld/s_lround.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2005 David Schultz <das@FreeBSD.ORG>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30 #include <limits.h>
  31 #include <fenv.h>
  32 #include <math.h>
  33
  34 #ifndef type
  35 __FBSDID("$FreeBSD$");
  36 #define type            double
  37 #define roundit         round
  38 #define dtype           long
  39 #define DTYPE_MIN       LONG_MIN
  40 #define DTYPE_MAX       LONG_MAX
  41 #define fn              lround
  42 #endif
  43
  44 /*
  45  * If type has more precision than dtype, the endpoints dtype_(min|max) are
  46  * of the form xxx.5; they are "out of range" because lround() rounds away
  47  * from 0.  On the other hand, if type has less precision than dtype, then
  48  * all values that are out of range are integral, so we might as well assume
  49  * that everything is in range.  At compile time, INRANGE(x) should reduce to
  50  * two floating-point comparisons in the former case, or TRUE otherwise.
  51  */
  52 static const type type_min = (type)DTYPE_MIN;
  53 static const type type_max = (type)DTYPE_MAX;
  54 static const type dtype_min = (type)DTYPE_MIN - 0.5;
  55 static const type dtype_max = (type)DTYPE_MAX + 0.5;
  56 #define INRANGE(x)      (dtype_max - type_max != 0.5 || \
  57                          ((x) > dtype_min && (x) < dtype_max))
  58
  59 dtype
  60 fn(type x)
  61 {
  62
  63         if (INRANGE(x)) {
  64                 x = roundit(x);
  65                 return ((dtype)x);
  66         } else {
  67 #ifdef FE_INVALID
  68                 feraiseexcept(FE_INVALID);
  69 #endif
  70                 return (DTYPE_MAX);
  71         }
  72 }