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/Q/log2l.c
          +++ new/usr/src/lib/libm/common/Q/log2l.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  /*
  23   23   * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  24   24   */
  25   25  /*
  26   26   * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  27   27   * Use is subject to license terms.
  28   28   */
  29   29  
  30   30  /*
  31   31   * log2l(x)

  32   32   * RETURN THE BASE 2 LOGARITHM OF X
  33   33   *
  34   34   * Method:
  35   35   *      purge off 0,INF, and NaN.
  36   36   *      n = ilogb(x)
  37   37   *      if (n<0) n+=1
  38   38   *      z = scalbn(x,-n)
  39   39   *      LOG2(x) = n + (1/ln2)*log(x)
  40   40   */
  41   41  
  42      -#pragma weak log2l = __log2l
       42 +#pragma weak __log2l = log2l
  43   43  
  44   44  #include "libm.h"
  45   45  #include "longdouble.h"
  46   46  
  47   47  static const long double
  48   48          zero    = 0.0L,
  49   49          half    = 0.5L,
  50   50          one     = 1.0L,
  51   51          invln2  = 1.442695040888963407359924681001892137427e+0000L;
  52   52  

  53   53  long double
  54   54  log2l(long double x) {
  55   55          int n;
  56   56  
  57   57          if (x == zero || !finitel(x))
  58   58                  return (logl(x));
  59   59          n = ilogbl(x);
  60   60          if (n < 0)
  61   61                  n += 1;
  62   62          x = scalbnl(x, -n);
  63   63          if (x == half)
  64   64                  return (n - one);
  65   65          return (n + invln2 * logl(x));
  66   66  }

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