alignment.h

Go to the documentation of this file.

 
 
/******************************************************************************
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
to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions :
 
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
******************************************************************************/
 
#ifndef ETL_ALIGNMENT_INCLUDED
#define ETL_ALIGNMENT_INCLUDED
 
#include "platform.h"
#include "type_traits.h"
#include "static_assert.h"
#include "error_handler.h"
#include "exception.h"
#include "utility.h"
 
#include <stdint.h>
 
 
namespace etl
{
  //***************************************************************************
  //***************************************************************************
  class alignment_exception : public etl::exception
  {
  public:
 
    alignment_exception(string_type reason_, string_type file_name_, numeric_type line_number_)
      : exception(reason_, file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class alignment_error : public alignment_exception
  {
  public:
 
    alignment_error(string_type file_name_, numeric_type line_number_)
      : alignment_exception(ETL_ERROR_TEXT("alignment:error", ETL_ALIGNMENT_FILE_ID"A"), file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class typed_storage_error : public alignment_exception
  {
  public:
 
    typed_storage_error(string_type file_name_, numeric_type line_number_)
      : alignment_exception(ETL_ERROR_TEXT("typed_storage:error", ETL_ALIGNMENT_FILE_ID"B"), file_name_, line_number_)
    {
    }
  };
 
  //*****************************************************************************
  //*****************************************************************************
  inline bool is_aligned(const void* p, size_t required_alignment)
  {
    uintptr_t address = reinterpret_cast<uintptr_t>(p);
    return (address % required_alignment) == 0U;
  }
 
  //*****************************************************************************
  //*****************************************************************************
  template <size_t Alignment>
  bool is_aligned(const void* p)
  {
    uintptr_t address = reinterpret_cast<uintptr_t>(p);
    return (address % Alignment) == 0U;
  }
 
  //*****************************************************************************
  //*****************************************************************************
  template <typename T>
  bool is_aligned(const void* p)
  {
    return is_aligned<etl::alignment_of<T>::value>(p);
  }
 
  namespace private_alignment
  {
#if ETL_USING_CPP11
    //***************************************************************************
    // Matcher.
    //***************************************************************************
    template <bool Is_Match, size_t Alignment, typename... TRest>
    class type_with_alignment_matcher;
 
    // Matching alignment.
    template <size_t Alignment, typename T1, typename... TRest>
    class type_with_alignment_matcher<true, Alignment, T1, TRest...> 
    {
    public:
    
      typedef T1 type;
    };
 
    // Non-matching alignment
    template <size_t Alignment, typename T1, typename T2, typename... TRest>
    class type_with_alignment_matcher <false, Alignment, T1, T2, TRest...> 
    {
    public:
    
      typedef typename type_with_alignment_matcher < Alignment <= etl::alignment_of<T2>::value , Alignment, T2, TRest... > ::type type;
    };
 
    // Non-matching alignment, none left.
    template <size_t Alignment, typename T1>
    class type_with_alignment_matcher <false, Alignment, T1> 
    {
    public:
    
      typedef char type;
    };
 
    //***************************************************************************
    // Helper.
    //***************************************************************************
    template <size_t Alignment, typename T1, typename... T>
    class type_with_alignment_helper 
    {
    public:
    
      typedef typename type_with_alignment_matcher<Alignment <= etl::alignment_of<T1>::value, Alignment, T1, T...>::type type;
    };
#else
    //***************************************************************************
    // Matcher.
    //***************************************************************************
    template <bool Is_Match, const size_t Alignment, typename T1 = void, typename T2 = void, typename T3 = void, typename T4 = void, 
                                                     typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void>
    class type_with_alignment_matcher;
 
    // Matching alignment.
    template <size_t Alignment, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7, typename T8>
    class type_with_alignment_matcher <true, Alignment, T1, T2, T3, T4, T5, T6, T7, T8>
    {
    public:
 
      typedef T1 type;
    };
 
    // Non-matching alignment.
    template <size_t Alignment, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7, typename T8>
    class type_with_alignment_matcher <false, Alignment, T1, T2, T3, T4, T5, T6, T7, T8>
    {
    public:
 
      typedef typename type_with_alignment_matcher<Alignment <= etl::alignment_of<T2>::value, Alignment, T2, T3, T4, T5, T6, T7, T8, void>::type type;
    };
 
    // Non-matching alignment, none left.
    template <size_t Alignment>
    class type_with_alignment_matcher <false, Alignment, void, void, void, void, void, void, void, void>
    {
    public:
 
      typedef char type;
    };
 
    //***************************************************************************
    // Helper.
    //***************************************************************************
    template <size_t Alignment, typename T1,        typename T2 = void, typename T3 = void, typename T4 = void,
                                typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void>
    class type_with_alignment_helper
    {
    public:
 
      typedef typename type_with_alignment_matcher<Alignment <= etl::alignment_of<T1>::value, Alignment, T1, T2, T3, T4, T5, T6, T7, T8>::type type;
    };
#endif
  }
 
  //***************************************************************************
  //***************************************************************************
  template <size_t Alignment>
  class type_with_alignment
  {
  public:
 
#if ETL_USING_CPP11
    typedef struct { alignas(Alignment) char dummy; } type;
#else
  #if ETL_NOT_USING_64BIT_TYPES
      typedef typename private_alignment::type_with_alignment_helper<Alignment, int_least8_t, int_least16_t, int32_t, float, double, void*>::type type;
  #else
      typedef typename private_alignment::type_with_alignment_helper<Alignment, int_least8_t, int_least16_t, int32_t, int64_t, float, double, void*>::type type;
  #endif
#endif
 
    ETL_STATIC_ASSERT(etl::alignment_of<type>::value == Alignment, "Unable to create the type with the specified alignment");
  };
 
#if ETL_USING_CPP11
  template <size_t Alignment>
  using type_with_alignment_t = typename type_with_alignment<Alignment>::type;
#endif
 
  //***************************************************************************
  //***************************************************************************
  template <size_t Length, const size_t Alignment>
  struct aligned_storage
  {
    struct type
    {
      //type() 
      //  : data()
      //{
      //}
 
      template <typename T>
      operator T& ()
      {
        ETL_STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((Alignment % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
        T* t = *this;
        return *t;
      }
 
      template <typename T>
      operator const T& () const
      {
        ETL_STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((Alignment % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
        const T* t = *this;
        return *t;
      }
 
      template <typename T>
      operator T* ()
      {
        ETL_STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((Alignment % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
        return reinterpret_cast<T*>(data);
      }
 
      template <typename T>
      operator const T* () const
      {
        ETL_STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((Alignment % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
        return reinterpret_cast<const T*>(data);
      }
 
      template <typename T>
      T& get_reference()
      {
        ETL_STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((Alignment % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
        T* t = *this;
        return *t;
      }
 
      template <typename T>
      const T& get_reference() const
      {
        ETL_STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((Alignment % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
        const T* t = *this;
        return *t;
      }
 
      template <typename T>
      T* get_address()
      {
        ETL_STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((Alignment % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
        return reinterpret_cast<T*>(data);
      }
 
      template <typename T>
      const T* get_address() const
      {
        ETL_STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((Alignment % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
        return reinterpret_cast<const T*>(data);
      }
 
#if ETL_USING_CPP11 && !defined(ETL_COMPILER_ARM5)
      alignas(Alignment) char data[Length];
#else
      union
      {
        char data[Length];
        typename etl::type_with_alignment<Alignment>::type etl_alignment_type; // A POD type that has the same alignment as Alignment.
      };
#endif
    };
  };
 
#if ETL_USING_CPP11
  template <size_t Length, const size_t Alignment>
  using aligned_storage_t = typename aligned_storage<Length, Alignment>::type;
#endif
 
  //***************************************************************************
  //***************************************************************************
  template <size_t Length, typename T>
  struct aligned_storage_as : public etl::aligned_storage<Length, etl::alignment_of<T>::value>
  {
  };
 
#if ETL_USING_CPP11
  template <size_t Length, typename T>
  using aligned_storage_as_t = typename aligned_storage_as<Length, T>::type;
#endif
 
  //***************************************************************************
  //***************************************************************************
  template <typename T>
  class typed_storage
  {
  public:
 
    typedef T        value_type;
    typedef T&       reference;
    typedef const T& const_reference;
    typedef T*       pointer;
    typedef const T* const_pointer;
 
    // Constructor
    typed_storage()
      : valid(false)
    {
    }
 
    //***************************************************************************
    //***************************************************************************
    ~typed_storage()
    {
    }
 
    //***************************************************************************
    //***************************************************************************
    bool has_value() const
    {
      return valid;
    }
 
#if ETL_USING_CPP11
    //***************************************************************************
    //***************************************************************************
    template<typename... Args>
    reference create(Args&&... args)
    {
      ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
      valid = true;
      return *::new (data.template get_address<char>()) value_type(etl::forward<Args>(args)...);
    }
#else
    //***************************************************************************
    //***************************************************************************
    template<typename T1>
    reference create(const T1& t1)
    {
      ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
      valid = true;
      return *::new (data.template get_address<char>()) value_type(t1);
    }
 
    //***************************************************************************
    //***************************************************************************
    template<typename T1, typename T2>
    reference create(const T1& t1, const T2& t2)
    {
      ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
      valid = true;
      return *::new (data.template get_address<char>()) value_type(t1, t2);
    }
 
    //***************************************************************************
    //***************************************************************************
    template<typename T1, typename T2, typename T3>
    reference create(const T1& t1, const T2& t2, const T3& t3)
    {
      ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
      valid = true;
      return *::new (data.template get_address<char>()) value_type(t1, t2, t3);
    }
 
    //***************************************************************************
    //***************************************************************************
    template<typename T1, typename T2, typename T3, typename T4>
    reference create(const T1& t1, const T2& t2, const T3& t3, const T4& t4)
    {
      ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
      valid = true;
      return *::new (data.template get_address<char>()) value_type(t1, t2, t3, t4);
    }
#endif
 
    //***************************************************************************
    //***************************************************************************
    void destroy()
    {
      ETL_ASSERT(has_value(), ETL_ERROR(etl::typed_storage_error));
      data.template get_reference<T>().~T();
      valid = false;
    }
 
    //***************************************************************************
    //***************************************************************************
    pointer operator->()
    {
      ETL_ASSERT(has_value(), ETL_ERROR(etl::typed_storage_error));
      return data.template get_address<value_type>();
    }
 
    //***************************************************************************
    //***************************************************************************
    const_pointer operator->() const
    {
      return operator->();
    }
 
    //***************************************************************************
    //***************************************************************************
    reference operator*()
    {
      return *operator->();
    }
 
    //***************************************************************************
    //***************************************************************************
    const_reference operator*() const
    {
      return *operator->();
    }
 
  private:
 
    typename aligned_storage_as<sizeof(value_type), value_type>::type data;
    bool valid;
  };
}
 
#endif