1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 
  22 /*
  23  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  24  */
  25 /*
  26  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  27  * Use is subject to license terms.
  28  */
  29 
  30 #pragma weak __rintl = rintl
  31 
  32 /*
  33  * rintl(long double x) return x rounded to integral according to
  34  * the prevailing rounding direction
  35  *
  36  * NOTE: aintl(x), anintl(x), ceill(x), floorl(x), and rintl(x) return result
  37  * with the same sign as x's, including 0.0L.
  38  */
  39 
  40 #include "libm.h"
  41 #include "longdouble.h"
  42 
  43 extern enum fp_precision_type __swapRP(enum fp_precision_type);
  44 
  45 static const double one = 1.0;
  46 static const long double qzero = 0.0L;
  47 
  48 long double
  49 rintl(long double x) {
  50         enum fp_precision_type rp;
  51         long double t, w, two112;
  52         int *pt = (int *) &two112;
  53 
  54         if (!finitel(x))
  55                 return (x + x);
  56 
  57         if (*(int *) &one != 0) {   /* set two112 = 2^112 */
  58                 pt[0] = 0x406f0000;
  59                 pt[1] = pt[2] = pt[3] = 0;
  60         } else {
  61                 pt[3] = 0x406f0000;
  62                 pt[0] = pt[1] = pt[2] = 0;
  63         }
  64 
  65         if (fabsl(x) >= two112)
  66                 return (x);     /* already an integer */
  67         t = copysignl(two112, x);
  68         rp = __swapRP(fp_extended);     /* make sure precision is long double */
  69         w = x + t;                      /* x+sign(x)*2^112 rounded to integer */
  70         (void) __swapRP(rp);            /* restore precision mode */
  71         if (w == t)
  72                 return (copysignl(qzero, x));   /* x rounded to zero */
  73         else
  74                 return (w - t);
  75 }