log.h

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/******************************************************************************
The MIT License(MIT)
 
Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com
 
Copyright(c) 2014 John Wellbelove
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files(the "Software"), to deal
in the Software without restriction, including without limitation the rights
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The above copyright notice and this permission notice shall be included in all
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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******************************************************************************/
 
#ifndef ETL_LOG_INCLUDED
#define ETL_LOG_INCLUDED
 
#include "platform.h"
 
#include <stddef.h>

 
namespace etl
{
  //***************************************************************************
  //***************************************************************************
  template <size_t Value, size_t Base>
  struct log
  {
    enum value_type
    {
      // Recursive definition.
      value = (Value >= Base) ? 1 + log<Value / Base, Base>::value : 0
    };
  };
 
  //***************************************************************************
  // Specialisation for N = 1
  //***************************************************************************
  template <size_t Base>
  struct log<1, Base>
  {
    enum value_type
    {
      value = 0
    };
  };
 
  //***************************************************************************
  // Specialisation for N = 0
  //***************************************************************************
  template <size_t Base>
  struct log<0, Base>
  {
    enum value_type
    {
      value = 0
    };
  };
 
#if ETL_USING_CPP17
  template <size_t Value, size_t Base>
  inline constexpr size_t log_v = log<Value, Base>::value;
#endif
 
  //***************************************************************************
  //***************************************************************************
  template <size_t Value>
  struct log2
  {
    enum value_type
    {
      value = log<Value, 2>::value
    };
  };
 
#if ETL_USING_CPP17
  template <size_t Value>
  inline constexpr size_t log2_v = log2<Value>::value;
#endif
 
  //***************************************************************************
  //***************************************************************************
  template <size_t Value>
  struct log10
  {
    enum value_type
    {
      value = log<Value, 10>::value
    };
  };
 
#if ETL_USING_CPP17
  template <size_t Value>
  inline constexpr size_t log10_v = log10<Value>::value;
#endif
} // namespace etl
 
#endif