ACE/ace/OS_NS_math.h

   1 // -*- C++ -*-
   2
   3 //=============================================================================
   4 /**
   5  *  @file   OS_NS_math.h
   6  *
   7  *  @author Douglas C. Schmidt <d.schmidt@vanderbilt.edu>
   8  *  @author Jesper S. M|ller<stophph@diku.dk>
   9  *  @author and a cast of thousands...
  10  */
  11 //=============================================================================
  12
  13 #ifndef ACE_OS_NS_MATH_H
  14 # define ACE_OS_NS_MATH_H
  15
  16 # include /**/ "ace/pre.h"
  17
  18 # include "ace/config-all.h"
  19
  20 # if !defined (ACE_LACKS_PRAGMA_ONCE)
  21 #  pragma once
  22 # endif /* ACE_LACKS_PRAGMA_ONCE */
  23
  24 #include "ace/os_include/os_math.h"
  25 #include <cmath>
  26
  27 #include /**/ "ace/ACE_export.h"
  28
  29 #if defined (ACE_EXPORT_MACRO)
  30 #  undef ACE_EXPORT_MACRO
  31 #endif
  32 #define ACE_EXPORT_MACRO ACE_Export
  33
  34
  35 /*
  36  * We inline and undef some functions that may be implemented
  37  * as macros on some platforms. This way macro definitions will
  38  * be usable later as there is no way to save the macro definition
  39  * using the pre-processor.
  40  */
  41 inline double ace_log2_helper (double x)
  42 {
  43 #if defined (log2)
  44   return log2 (x);
  45 #undef log2
  46 #else
  47 #  if !defined (ACE_LACKS_LOG2)
  48   return std::log2 (x);
  49 #  else
  50   /*
  51     ==================================================================
  52
  53                 log (x)
  54                    k
  55       log (x) = -------
  56          b      log (b)
  57                    k
  58
  59     meaning the binary logarithm of x using the natural logarithm, for
  60     example, is:
  61
  62
  63                 log (x)
  64                    e
  65       log (x) = -------
  66          2      log (2)
  67                    e
  68
  69     ==================================================================
  70    */
  71
  72   // Precomputed value of 1/log(2.0).  Saves an expensive division and
  73   // computing log(2.0) in each call.
  74   double const _1_ln2 = 1.442695040888963407359924681002;
  75
  76   return log (x) * _1_ln2;
  77 #  endif /* !ACE_LACKS_LOG2 */
  78 #endif /* defined (log2) */
  79 }
  80
  81
  82 ACE_BEGIN_VERSIONED_NAMESPACE_DECL
  83
  84 namespace ACE_OS
  85 {
  86   /// This method computes the largest integral value not greater than x.
  87   template <typename T>
  88   inline
  89   T floor (T x)
  90   {
  91     return std::floor (x);
  92   }
  93
  94   /// This method computes the smallest integral value not less than x.
  95   template <typename T>
  96   inline
  97   T ceil (T x)
  98   {
  99     return std::ceil (x);
 100   }
 101
 102   /// This method computes the base-2 logarithm of x.
 103   ACE_NAMESPACE_INLINE_FUNCTION
 104   double log2 (double x);
 105 } /* namespace ACE_OS */
 106
 107 ACE_END_VERSIONED_NAMESPACE_DECL
 108
 109 # if defined (ACE_HAS_INLINED_OSCALLS)
 110 #   if defined (ACE_INLINE)
 111 #     undef ACE_INLINE
 112 #   endif /* ACE_INLINE */
 113 #   define ACE_INLINE inline
 114 #   include "ace/OS_NS_math.inl"
 115 # endif /* ACE_HAS_INLINED_OSCALLS */
 116
 117 # include /**/ "ace/post.h"
 118 #endif /* ACE_OS_NS_MATH_H */