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 2006 Sun Microsystems, Inc.  All rights reserved.
  28  * Use is subject to license terms.
  29  */
  30 
  31 #pragma weak __ldexp = ldexp
  32 
  33 #include "libm.h"
  34 #include <errno.h>
  35 
  36 double
  37 ldexp(double x, int n)
  38 {
  39         int *px = (int *)&x, ix = px[HIWORD] & ~0x80000000;
  40 
  41         if (ix >= 0x7ff00000 || (px[LOWORD] | ix) == 0)
  42 #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
  43                 return (ix >= 0x7ff80000 ? x : x + x);
  44 
  45         /* assumes sparc-like QNaN */
  46 #else
  47                 return (x + x);
  48 #endif
  49         x = scalbn(x, n);
  50         ix = px[HIWORD] & ~0x80000000;
  51 
  52         /*
  53          * SVID3 requires both overflow and underflow cases to set errno
  54          * XPG3/XPG4/XPG4.2/SUSv2 requires overflow to set errno
  55          */
  56         if (ix >= 0x7ff00000 || (px[LOWORD] | ix) == 0)
  57                 errno = ERANGE;
  58 
  59         return (x);
  60 }