5261 libm should stop using synonyms.h
5298 fabs is 0-sized, confuses dis(1) and others
Reviewed by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
Approved by: Gordon Ross <gwr@nexenta.com>

          --- old/usr/src/lib/libm/common/C/exp2.c
          +++ new/usr/src/lib/libm/common/C/exp2.c

   1    1  /*
   2    2   * CDDL HEADER START
   3    3   *
   4    4   * The contents of this file are subject to the terms of the
   5    5   * Common Development and Distribution License (the "License").
   6    6   * You may not use this file except in compliance with the License.
   7    7   *
   8    8   * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9    9   * or http://www.opensolaris.org/os/licensing.
  10   10   * See the License for the specific language governing permissions
  11   11   * and limitations under the License.
  12   12   *
  13   13   * When distributing Covered Code, include this CDDL HEADER in each
  14   14   * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15   15   * If applicable, add the following below this CDDL HEADER, with the
  16   16   * fields enclosed by brackets "[]" replaced with your own identifying
  17   17   * information: Portions Copyright [yyyy] [name of copyright owner]
  18   18   *

  19   19   * CDDL HEADER END
  20   20   */
  21   21  /*
  22   22   * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  23   23   */
  24   24  /*
  25   25   * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  26   26   * Use is subject to license terms.
  27   27   */
  28   28  
  29      -#pragma weak exp2 = __exp2
       29 +#pragma weak __exp2 = exp2
  30   30  
  31   31  /* INDENT OFF */
  32   32  /*
  33   33   * exp2(x)
  34   34   * Code by K.C. Ng for SUN 4.0 libm.
  35   35   * Method :
  36   36   *      exp2(x) = 2**x = 2**((x-anint(x))+anint(x))
  37   37   *              = 2**anint(x)*2**(x-anint(x))
  38   38   *              = 2**anint(x)*exp((x-anint(x))*ln2)
  39   39   */

  40   40  /* INDENT ON */
  41   41  
  42   42  #include "libm.h"
  43   43  
  44   44  static const double C[] = {
  45   45          0.0,
  46   46          1.0,
  47   47          0.5,
  48   48          6.93147180559945286227e-01,
  49   49          1.0e300,
  50   50          1.0e-300,
  51   51  };
  52   52  
  53   53  #define zero    C[0]
  54   54  #define one     C[1]
  55   55  #define half    C[2]
  56   56  #define ln2     C[3]
  57   57  #define huge    C[4]
  58   58  #define tiny    C[5]
  59   59  
  60   60  double
  61   61  exp2(double x) {
  62   62          int     ix, hx, k;
  63   63          double  t;
  64   64  
  65   65          ix = ((int *)&x)[HIWORD];
  66   66          hx = ix & ~0x80000000;
  67   67  
  68   68          if (hx >= 0x4090e000) { /* |x| >= 1080 or x is nan */
  69   69                  if (hx >= 0x7ff00000) { /* x is inf or nan */
  70   70                          if (ix == 0xfff00000 && ((int *)&x)[LOWORD] == 0)
  71   71                                  return (zero);
  72   72                          return (x * x);
  73   73                  }
  74   74                  t = (ix < 0)? tiny : huge;
  75   75                  return (t * t);
  76   76          }
  77   77  
  78   78          if (hx < 0x3fe00000) {  /* |x| < 0.5 */
  79   79                  if (hx < 0x3c000000)
  80   80                          return (one + x);
  81   81                  return (exp(ln2 * x));
  82   82          }
  83   83  
  84   84          k = (int)x;
  85   85          if (x != (double)k)
  86   86                  k = (int)((ix < 0)? x - half : x + half);
  87   87          return (scalbn(exp(ln2 * (x - (double)k)), k));
  88   88  }

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