boost/endian/buffers.hpp

//  boost/endian/buffers.hpp  ----------------------------------------------------------//
//  (C) Copyright Darin Adler 2000
//  (C) Copyright Beman Dawes 2006, 2009, 2014
//  Distributed under the Boost Software License, Version 1.0.
//  See http://www.boost.org/LICENSE_1_0.txt
//  See library home page at http://www.boost.org/libs/endian
//--------------------------------------------------------------------------------------//
//  Original design developed by Darin Adler based on classes developed by Mark
//  Borgerding. Four original class templates were combined into a single endian
//  class template by Beman Dawes, who also added the unrolled_byte_loops sign
//  partial specialization to correctly extend the sign when cover integer size
//  differs from endian representation size.
// TODO: When a compiler supporting constexpr becomes available, try possible uses.
#ifndef BOOST_ENDIAN_BUFFERS_HPP
#define BOOST_ENDIAN_BUFFERS_HPP
#if defined(_MSC_VER)  
# pragma warning(push)  
# pragma warning(disable:4365)  // conversion ... signed/unsigned mismatch
#endif
#ifdef BOOST_ENDIAN_LOG
# include <iostream>
#endif
#if defined(__BORLANDC__) || defined( __CODEGEARC__)
# pragma pack(push, 1)
#endif
#include <boost/config.hpp>
#include <boost/predef/detail/endian_compat.h>
#include <boost/endian/conversion.hpp>
#include <boost/type_traits/is_signed.hpp>
#include <boost/cstdint.hpp>
#include <boost/static_assert.hpp>
#include <boost/core/scoped_enum.hpp>
#include <iosfwd>
#include <climits>
# if CHAR_BIT != 8
#   error Platforms with CHAR_BIT != 8 are not supported
# endif
# ifdef BOOST_NO_CXX11_DEFAULTED_FUNCTIONS
#   define BOOST_ENDIAN_DEFAULT_CONSTRUCT {}          // C++03
# else
#   define BOOST_ENDIAN_DEFAULT_CONSTRUCT = default;  // C++0x
# endif
# if defined(BOOST_NO_CXX11_DEFAULTED_FUNCTIONS) && defined(BOOST_ENDIAN_FORCE_PODNESS)
#   define BOOST_ENDIAN_NO_CTORS
# endif
//----------------------------------  synopsis  ----------------------------------------//
namespace boost
{
namespace endian
{
  BOOST_SCOPED_ENUM_START(align)
  {no, yes
#   ifdef BOOST_ENDIAN_DEPRECATED_NAMES
      , unaligned = no, aligned = yes
#   endif
  }; BOOST_SCOPED_ENUM_END
  template <BOOST_SCOPED_ENUM(order) Order, class T, std::size_t n_bits,
    BOOST_SCOPED_ENUM(align) A = align::no>
      class endian_buffer;
  // aligned big endian signed integer buffers
  typedef endian_buffer<order::big, int8_t, 8, align::yes>       big_int8_buf_at;
  typedef endian_buffer<order::big, int16_t, 16, align::yes>     big_int16_buf_at;
  typedef endian_buffer<order::big, int32_t, 32, align::yes>     big_int32_buf_at;
  typedef endian_buffer<order::big, int64_t, 64, align::yes>     big_int64_buf_at;
  // aligned big endian unsigned integer buffers
  typedef endian_buffer<order::big, uint8_t, 8, align::yes>      big_uint8_buf_at;
  typedef endian_buffer<order::big, uint16_t, 16, align::yes>    big_uint16_buf_at;
  typedef endian_buffer<order::big, uint32_t, 32, align::yes>    big_uint32_buf_at;
  typedef endian_buffer<order::big, uint64_t, 64, align::yes>    big_uint64_buf_at;
  // aligned little endian signed integer buffers
  typedef endian_buffer<order::little, int8_t, 8, align::yes>    little_int8_buf_at;
  typedef endian_buffer<order::little, int16_t, 16, align::yes>  little_int16_buf_at;
  typedef endian_buffer<order::little, int32_t, 32, align::yes>  little_int32_buf_at;
  typedef endian_buffer<order::little, int64_t, 64, align::yes>  little_int64_buf_at;
  // aligned little endian unsigned integer buffers
  typedef endian_buffer<order::little, uint8_t, 8, align::yes>   little_uint8_buf_at;
  typedef endian_buffer<order::little, uint16_t, 16, align::yes> little_uint16_buf_at;
  typedef endian_buffer<order::little, uint32_t, 32, align::yes> little_uint32_buf_at;
  typedef endian_buffer<order::little, uint64_t, 64, align::yes> little_uint64_buf_at;
  // aligned native endian typedefs are not provided because
  // <cstdint> types are superior for this use case
  // unaligned big endian signed integer buffers
  typedef endian_buffer<order::big, int_least8_t, 8>        big_int8_buf_t;
  typedef endian_buffer<order::big, int_least16_t, 16>      big_int16_buf_t;
  typedef endian_buffer<order::big, int_least32_t, 24>      big_int24_buf_t;
  typedef endian_buffer<order::big, int_least32_t, 32>      big_int32_buf_t;
  typedef endian_buffer<order::big, int_least64_t, 40>      big_int40_buf_t;
  typedef endian_buffer<order::big, int_least64_t, 48>      big_int48_buf_t;
  typedef endian_buffer<order::big, int_least64_t, 56>      big_int56_buf_t;
  typedef endian_buffer<order::big, int_least64_t, 64>      big_int64_buf_t;
  // unaligned big endian unsigned integer buffers
  typedef endian_buffer<order::big, uint_least8_t, 8>       big_uint8_buf_t;
  typedef endian_buffer<order::big, uint_least16_t, 16>     big_uint16_buf_t;
  typedef endian_buffer<order::big, uint_least32_t, 24>     big_uint24_buf_t;
  typedef endian_buffer<order::big, uint_least32_t, 32>     big_uint32_buf_t;
  typedef endian_buffer<order::big, uint_least64_t, 40>     big_uint40_buf_t;
  typedef endian_buffer<order::big, uint_least64_t, 48>     big_uint48_buf_t;
  typedef endian_buffer<order::big, uint_least64_t, 56>     big_uint56_buf_t;
  typedef endian_buffer<order::big, uint_least64_t, 64>     big_uint64_buf_t;
  // unaligned little endian signed integer buffers
  typedef endian_buffer<order::little, int_least8_t, 8>     little_int8_buf_t;
  typedef endian_buffer<order::little, int_least16_t, 16>   little_int16_buf_t;
  typedef endian_buffer<order::little, int_least32_t, 24>   little_int24_buf_t;
  typedef endian_buffer<order::little, int_least32_t, 32>   little_int32_buf_t;
  typedef endian_buffer<order::little, int_least64_t, 40>   little_int40_buf_t;
  typedef endian_buffer<order::little, int_least64_t, 48>   little_int48_buf_t;
  typedef endian_buffer<order::little, int_least64_t, 56>   little_int56_buf_t;
  typedef endian_buffer<order::little, int_least64_t, 64>   little_int64_buf_t;
  // unaligned little endian unsigned integer buffers
  typedef endian_buffer<order::little, uint_least8_t, 8>    little_uint8_buf_t;
  typedef endian_buffer<order::little, uint_least16_t, 16>  little_uint16_buf_t;
  typedef endian_buffer<order::little, uint_least32_t, 24>  little_uint24_buf_t;
  typedef endian_buffer<order::little, uint_least32_t, 32>  little_uint32_buf_t;
  typedef endian_buffer<order::little, uint_least64_t, 40>  little_uint40_buf_t;
  typedef endian_buffer<order::little, uint_least64_t, 48>  little_uint48_buf_t;
  typedef endian_buffer<order::little, uint_least64_t, 56>  little_uint56_buf_t;
  typedef endian_buffer<order::little, uint_least64_t, 64>  little_uint64_buf_t;
# ifdef BOOST_BIG_ENDIAN
  // unaligned native endian signed integer buffers
  typedef big_int8_buf_t   native_int8_buf_t;
  typedef big_int16_buf_t  native_int16_buf_t;
  typedef big_int24_buf_t  native_int24_buf_t;
  typedef big_int32_buf_t  native_int32_buf_t;
  typedef big_int40_buf_t  native_int40_buf_t;
  typedef big_int48_buf_t  native_int48_buf_t;
  typedef big_int56_buf_t  native_int56_buf_t;
  typedef big_int64_buf_t  native_int64_buf_t;
  // unaligned native endian unsigned integer buffers
  typedef big_uint8_buf_t   native_uint8_buf_t;
  typedef big_uint16_buf_t  native_uint16_buf_t;
  typedef big_uint24_buf_t  native_uint24_buf_t;
  typedef big_uint32_buf_t  native_uint32_buf_t;
  typedef big_uint40_buf_t  native_uint40_buf_t;
  typedef big_uint48_buf_t  native_uint48_buf_t;
  typedef big_uint56_buf_t  native_uint56_buf_t;
  typedef big_uint64_buf_t  native_uint64_buf_t;
# else
  // unaligned native endian signed integer buffers
  typedef little_int8_buf_t   native_int8_buf_t;
  typedef little_int16_buf_t  native_int16_buf_t;
  typedef little_int24_buf_t  native_int24_buf_t;
  typedef little_int32_buf_t  native_int32_buf_t;
  typedef little_int40_buf_t  native_int40_buf_t;
  typedef little_int48_buf_t  native_int48_buf_t;
  typedef little_int56_buf_t  native_int56_buf_t;
  typedef little_int64_buf_t  native_int64_buf_t;
  // unaligned native endian unsigned integer buffers
  typedef little_uint8_buf_t   native_uint8_buf_t;
  typedef little_uint16_buf_t  native_uint16_buf_t;
  typedef little_uint24_buf_t  native_uint24_buf_t;
  typedef little_uint32_buf_t  native_uint32_buf_t;
  typedef little_uint40_buf_t  native_uint40_buf_t;
  typedef little_uint48_buf_t  native_uint48_buf_t;
  typedef little_uint56_buf_t  native_uint56_buf_t;
  typedef little_uint64_buf_t  native_uint64_buf_t;
# endif
  // Stream inserter
  template <class charT, class traits, BOOST_SCOPED_ENUM(order) Order, class T,
    std::size_t n_bits, BOOST_SCOPED_ENUM(align) A>
  std::basic_ostream<charT, traits>&
    operator<<(std::basic_ostream<charT, traits>& os,
      const endian_buffer<Order, T, n_bits, A>& x)
  {
    return os << x.value();
  }
  // Stream extractor 
  template <class charT, class traits, BOOST_SCOPED_ENUM(order) Order, class T,
    std::size_t n_bits, BOOST_SCOPED_ENUM(align) A>
  std::basic_istream<charT, traits>&
    operator>>(std::basic_istream<charT, traits>& is,
      endian_buffer<Order, T, n_bits, A>& x)
  {
    T i;
    if (is >> i)
      x = i;
    return is;
  }
//----------------------------------  end synopsis  ------------------------------------//
  namespace detail
  {
    // Unrolled loops for loading and storing streams of bytes.
    template <typename T, std::size_t n_bytes,
      bool sign=boost::is_signed<T>::value >
    struct unrolled_byte_loops
    {
      typedef unrolled_byte_loops<T, n_bytes - 1, sign> next;
      static T load_big(const unsigned char* bytes) BOOST_NOEXCEPT
        { return static_cast<T>(*(bytes - 1) | (next::load_big(bytes - 1) << 8)); }
      static T load_little(const unsigned char* bytes) BOOST_NOEXCEPT
        { return static_cast<T>(*bytes | (next::load_little(bytes + 1) << 8)); }
      static void store_big(char* bytes, T value) BOOST_NOEXCEPT
        {
          *(bytes - 1) = static_cast<char>(value);
          next::store_big(bytes - 1, static_cast<T>(value >> 8));
        }
      static void store_little(char* bytes, T value) BOOST_NOEXCEPT
        {
          *bytes = static_cast<char>(value);
          next::store_little(bytes + 1, static_cast<T>(value >> 8));
        }
    };
    template <typename T>
    struct unrolled_byte_loops<T, 1, false>
    {
      static T load_big(const unsigned char* bytes) BOOST_NOEXCEPT
        { return *(bytes - 1); }
      static T load_little(const unsigned char* bytes) BOOST_NOEXCEPT
        { return *bytes; }
      static void store_big(char* bytes, T value) BOOST_NOEXCEPT
        { *(bytes - 1) = static_cast<char>(value); }
      static void store_little(char* bytes, T value) BOOST_NOEXCEPT
        { *bytes = static_cast<char>(value); }
    };
    template <typename T>
    struct unrolled_byte_loops<T, 1, true>
    {
      static T load_big(const unsigned char* bytes) BOOST_NOEXCEPT
        { return *reinterpret_cast<const signed char*>(bytes - 1); }
      static T load_little(const unsigned char* bytes) BOOST_NOEXCEPT
        { return *reinterpret_cast<const signed char*>(bytes); }
      static void store_big(char* bytes, T value)  BOOST_NOEXCEPT
        { *(bytes - 1) = static_cast<char>(value); }
      static void store_little(char* bytes, T value) BOOST_NOEXCEPT
        { *bytes = static_cast<char>(value); }
    };
    template <typename T, std::size_t n_bytes>
    inline
    T load_big_endian(const void* bytes) BOOST_NOEXCEPT
    {
      return unrolled_byte_loops<T, n_bytes>::load_big
        (static_cast<const unsigned char*>(bytes) + n_bytes);
    }
    template <typename T, std::size_t n_bytes>
    inline
    T load_little_endian(const void* bytes) BOOST_NOEXCEPT
    {
#   if defined(__x86_64__) || defined(_M_X64) || defined(__i386) || defined(_M_IX86)
      // On x86 (which is little endian), unaligned loads are permitted
      if (sizeof(T) == n_bytes)  // GCC 4.9, VC++ 14.0, and probably others, elide this
                                 // test and generate code only for the applicable return
                                 // case since sizeof(T) and n_bytes are known at compile
                                 // time.
      {
        return *reinterpret_cast<T const *>(bytes);
      }
#   endif
      return unrolled_byte_loops<T, n_bytes>::load_little
        (static_cast<const unsigned char*>(bytes));
    }
    template <typename T, std::size_t n_bytes>
    inline
    void store_big_endian(void* bytes, T value) BOOST_NOEXCEPT
    {
      unrolled_byte_loops<T, n_bytes>::store_big
        (static_cast<char*>(bytes) + n_bytes, value);
    }
    template <typename T, std::size_t n_bytes>
    inline
    void store_little_endian(void* bytes, T value) BOOST_NOEXCEPT
    {
#     if defined(__x86_64__) || defined(_M_X64) || defined(__i386) || defined(_M_IX86)
      // On x86 (which is little endian), unaligned stores are permitted
      if (sizeof(T) == n_bytes)  // GCC 4.9, VC++ 14.0, and probably others, elide this
                                 // test and generate code only for the applicable return
                                 // case since sizeof(T) and n_bytes are known at compile
                                 // time.
      {
        *reinterpret_cast<T *>(bytes) = value;
        return;
      }
#     endif
      unrolled_byte_loops<T, n_bytes>::store_little
        (static_cast<char*>(bytes), value);
    }
  } // namespace detail
# ifdef BOOST_ENDIAN_LOG
    bool endian_log(true);
# endif
//  endian_buffer class template specializations  --------------------------------------//
    //  Specializations that represent unaligned bytes.
    //  Taking an integer type as a parameter provides a nice way to pass both
    //  the size and signedness of the desired integer and get the appropriate
    //  corresponding integer type for the interface.
    // Q: Should endian_buffer supply "value_type operator value_type() const noexcept"?
    // A: No. The rationale for endian_buffers is to prevent high-cost hidden
    //    conversions. If an implicit conversion operator is supplied, hidden conversions
    //    can occur.
    //  unaligned big endian_buffer specialization
    template <typename T, std::size_t n_bits>
    class endian_buffer< order::big, T, n_bits, align::no >
    {
        BOOST_STATIC_ASSERT( (n_bits/8)*8 == n_bits );
      public:
        typedef T value_type;
#     ifndef BOOST_ENDIAN_NO_CTORS
        endian_buffer() BOOST_ENDIAN_DEFAULT_CONSTRUCT
        explicit endian_buffer(T val) BOOST_NOEXCEPT
        { 
#       ifdef BOOST_ENDIAN_LOG
          if ( endian_log )
            std::cout << "big, unaligned, "
              << n_bits << "-bits, construct(" << val << ")\n";
#       endif
          detail::store_big_endian<T, n_bits/8>(m_value, val);
        }
#     endif
        endian_buffer & operator=(T val) BOOST_NOEXCEPT
        {
#       ifdef BOOST_ENDIAN_LOG
          if (endian_log)
            std::cout << "big, unaligned, " << n_bits << "-bits, assign(" << val << ")\n";
#       endif
          detail::store_big_endian<T, n_bits/8>(m_value, val);
          return *this;
        }
        value_type value() const BOOST_NOEXCEPT
        { 
#       ifdef BOOST_ENDIAN_LOG
          if ( endian_log )
            std::cout << "big, unaligned, " << n_bits << "-bits, convert("
              << detail::load_big_endian<T, n_bits/8>(m_value) << ")\n";
#       endif
          return detail::load_big_endian<T, n_bits/8>(m_value);
        }
        const char* data() const BOOST_NOEXCEPT  { return m_value; }
      protected:
        char m_value[n_bits/8];
    };
    //  unaligned little endian_buffer specialization
    template <typename T, std::size_t n_bits>
    class endian_buffer< order::little, T, n_bits, align::no >
    {
        BOOST_STATIC_ASSERT( (n_bits/8)*8 == n_bits );
      public:
        typedef T value_type;
#     ifndef BOOST_ENDIAN_NO_CTORS
        endian_buffer() BOOST_ENDIAN_DEFAULT_CONSTRUCT
        explicit endian_buffer(T val) BOOST_NOEXCEPT
        { 
#       ifdef BOOST_ENDIAN_LOG
          if ( endian_log )
            std::cout << "little, unaligned, " << n_bits << "-bits, construct("
              << val << ")\n";
#       endif
          detail::store_little_endian<T, n_bits/8>(m_value, val);
        }
#     endif
        endian_buffer & operator=(T val) BOOST_NOEXCEPT
          { detail::store_little_endian<T, n_bits/8>(m_value, val); return *this; }
        value_type value() const BOOST_NOEXCEPT
        { 
#       ifdef BOOST_ENDIAN_LOG
          if ( endian_log )
            std::cout << "little, unaligned, " << n_bits << "-bits, convert("
              << detail::load_little_endian<T, n_bits/8>(m_value) << ")\n";
#       endif
          return detail::load_little_endian<T, n_bits/8>(m_value);
        }
        const char* data() const BOOST_NOEXCEPT  { return m_value; }
      protected:
        char m_value[n_bits/8];
    };
  //  align::yes specializations; only n_bits == 16/32/64 supported
    //  aligned big endian_buffer specialization
    template <typename T, std::size_t n_bits>
    class endian_buffer<order::big, T, n_bits, align::yes>
    {
        BOOST_STATIC_ASSERT( (n_bits/8)*8 == n_bits );
        BOOST_STATIC_ASSERT( sizeof(T) == n_bits/8 );
      public:
        typedef T value_type;
#     ifndef BOOST_ENDIAN_NO_CTORS
        endian_buffer() BOOST_ENDIAN_DEFAULT_CONSTRUCT
        explicit endian_buffer(T val) BOOST_NOEXCEPT
        {
#       ifdef BOOST_ENDIAN_LOG
          if ( endian_log )
            std::cout << "big, aligned, " << n_bits
              << "-bits, construct(" << val << ")\n";
#       endif
          m_value = ::boost::endian::native_to_big(val);
        }
#     endif  
        endian_buffer& operator=(T val) BOOST_NOEXCEPT
        {
          m_value = ::boost::endian::native_to_big(val);
          return *this;
        }
        //operator value_type() const BOOST_NOEXCEPT
        //{                                                                       
        //  return ::boost::endian::big_to_native(m_value);
        //}
        value_type value() const BOOST_NOEXCEPT
        {
#       ifdef BOOST_ENDIAN_LOG
          if ( endian_log )
            std::cout << "big, aligned, " << n_bits << "-bits, convert("
              << ::boost::endian::big_to_native(m_value) << ")\n";
#       endif
          return ::boost::endian::big_to_native(m_value);
        }
        const char* data() const BOOST_NOEXCEPT
          {return reinterpret_cast<const char*>(&m_value);}
      protected:
        T m_value;
    };
    //  aligned little endian_buffer specialization
    template <typename T, std::size_t n_bits>
    class endian_buffer<order::little, T, n_bits, align::yes>
    {
        BOOST_STATIC_ASSERT( (n_bits/8)*8 == n_bits );
        BOOST_STATIC_ASSERT( sizeof(T) == n_bits/8 );
      public:
        typedef T value_type;
#     ifndef BOOST_ENDIAN_NO_CTORS
        endian_buffer() BOOST_ENDIAN_DEFAULT_CONSTRUCT
        explicit endian_buffer(T val) BOOST_NOEXCEPT
        {
#       ifdef BOOST_ENDIAN_LOG
          if ( endian_log )
            std::cout << "little, aligned, " << n_bits
              << "-bits, construct(" << val << ")\n";
#       endif
          m_value = ::boost::endian::native_to_little(val);
        }
#     endif  
        endian_buffer& operator=(T val) BOOST_NOEXCEPT
        {
          m_value = ::boost::endian::native_to_little(val);
          return *this;
        }
        value_type value() const BOOST_NOEXCEPT
        {
#       ifdef BOOST_ENDIAN_LOG
          if ( endian_log )
            std::cout << "little, aligned, " << n_bits << "-bits, convert("
              << ::boost::endian::little_to_native(m_value) << ")\n";
#       endif
          return ::boost::endian::little_to_native(m_value);
        }
        const char* data() const BOOST_NOEXCEPT
          {return reinterpret_cast<const char*>(&m_value);}
      protected:
        T m_value;
    };
} // namespace endian
} // namespace boost
#if defined(__BORLANDC__) || defined( __CODEGEARC__)
# pragma pack(pop)
#endif
#if defined(_MSC_VER)  
# pragma warning(pop)  
#endif 
#endif // BOOST_ENDIAN_BUFFERS_HPP