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 /*
  27  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
  28  * Use is subject to license terms.
  29  */
  30 
  31 #pragma weak __scalb = scalb
  32 #pragma weak _scalb = scalb
  33 
  34 #include "libm.h"
  35 
  36 double
  37 scalb(double x, double fn)
  38 {
  39         int hn, in, n;
  40         double z;
  41 
  42         if (isnan(x) || isnan(fn))
  43                 return (x * fn);
  44 
  45         in = ((int *)&fn)[HIWORD];
  46         hn = in & ~0x80000000;
  47 
  48         if (hn == 0x7ff00000)           /* fn is inf */
  49                 return (_SVID_libm_err(x, fn, 47));
  50 
  51         /* see if fn is an integer without raising inexact */
  52         if (hn >= 0x43300000) {
  53                 /* |fn| >= 2^52, so it must be an integer */
  54                 n = (in < 0) ? -65000 : 65000;
  55         } else if (hn < 0x3ff00000) {
  56                 /* |fn| < 1, so it must be zero or non-integer */
  57                 return ((fn == 0.0) ? x : (x - x) / (x - x));
  58         } else if (hn < 0x41400000) {
  59                 /* |fn| < 2^21 */
  60                 if ((hn & ((1 << (0x413 - (hn >> 20))) - 1)) |
  61                     ((int *)&fn)[LOWORD])
  62                         return ((x - x) / (x - x));
  63 
  64                 n = (int)fn;
  65         } else {
  66                 if (((int *)&fn)[LOWORD] & ((1 << (0x433 - (hn >> 20))) - 1))
  67                         return ((x - x) / (x - x));
  68 
  69                 n = (in < 0) ? -65000 : 65000;
  70         }
  71 
  72         z = scalbn(x, n);
  73 
  74         if (z != x) {
  75                 if (z == 0.0)
  76                         return (_SVID_libm_err(x, fn, 33));
  77 
  78                 if (!finite(z))
  79                         return (_SVID_libm_err(x, fn, 32));
  80         }
  81 
  82         return (z);
  83 }