boost/endian/detail/endian_load.hpp
#ifndef BOOST_ENDIAN_DETAIL_ENDIAN_LOAD_HPP_INCLUDED
#define BOOST_ENDIAN_DETAIL_ENDIAN_LOAD_HPP_INCLUDED
// Copyright 2019 Peter Dimov
//
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
#include <boost/endian/detail/endian_reverse.hpp>
#include <boost/endian/detail/order.hpp>
#include <boost/endian/detail/integral_by_size.hpp>
#include <boost/endian/detail/is_trivially_copyable.hpp>
#include <boost/endian/detail/static_assert.hpp>
#include <type_traits>
#include <cstddef>
#include <cstring>
namespace boost
{
namespace endian
{
namespace detail
{
template<class T, std::size_t N1, order O1, std::size_t N2, order O2> struct endian_load_impl
{
};
} // namespace detail
// Requires:
//
// sizeof(T) must be 1, 2, 4, or 8
// 1 <= N <= sizeof(T)
// T is TriviallyCopyable
// if N < sizeof(T), T is integral or enum
template<class T, std::size_t N, order Order>
inline T endian_load( unsigned char const * p ) BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( sizeof(T) == 1 || sizeof(T) == 2 || sizeof(T) == 4 || sizeof(T) == 8 );
BOOST_ENDIAN_STATIC_ASSERT( N >= 1 && N <= sizeof(T) );
return detail::endian_load_impl<T, sizeof(T), order::native, N, Order>()( p );
}
namespace detail
{
// same endianness, same size
template<class T, std::size_t N, order O> struct endian_load_impl<T, N, O, N, O>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( is_trivially_copyable<T>::value );
T t;
std::memcpy( &t, p, N );
return t;
}
};
// same size, reverse endianness
template<class T, std::size_t N, order O1, order O2> struct endian_load_impl<T, N, O1, N, O2>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( is_trivially_copyable<T>::value );
typename integral_by_size<N>::type tmp;
std::memcpy( &tmp, p, N );
endian_reverse_inplace( tmp );
T t;
std::memcpy( &t, &tmp, N );
return t;
}
};
// expanding load 1 -> 2
template<class T, order Order> struct endian_load_impl<T, 2, Order, 1, order::little>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 2 ];
tmp[0] = p[0];
tmp[1] = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
return boost::endian::endian_load<T, 2, order::little>( tmp );
}
};
template<class T, order Order> struct endian_load_impl<T, 2, Order, 1, order::big>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 2 ];
tmp[0] = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
tmp[1] = p[0];
return boost::endian::endian_load<T, 2, order::big>( tmp );
}
};
// expanding load 1 -> 4
template<class T, order Order> struct endian_load_impl<T, 4, Order, 1, order::little>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 4 ];
unsigned char fill = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
tmp[0] = p[0];
tmp[1] = fill;
tmp[2] = fill;
tmp[3] = fill;
return boost::endian::endian_load<T, 4, order::little>( tmp );
}
};
template<class T, order Order> struct endian_load_impl<T, 4, Order, 1, order::big>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 4 ];
unsigned char fill = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
tmp[0] = fill;
tmp[1] = fill;
tmp[2] = fill;
tmp[3] = p[0];
return boost::endian::endian_load<T, 4, order::big>( tmp );
}
};
// expanding load 2 -> 4
template<class T, order Order> struct endian_load_impl<T, 4, Order, 2, order::little>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 4 ];
unsigned char fill = std::is_signed<T>::value && ( p[1] & 0x80 )? 0xFF: 0x00;
tmp[0] = p[0];
tmp[1] = p[1];
tmp[2] = fill;
tmp[3] = fill;
return boost::endian::endian_load<T, 4, order::little>( tmp );
}
};
template<class T, order Order> struct endian_load_impl<T, 4, Order, 2, order::big>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 4 ];
unsigned char fill = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
tmp[0] = fill;
tmp[1] = fill;
tmp[2] = p[0];
tmp[3] = p[1];
return boost::endian::endian_load<T, 4, order::big>( tmp );
}
};
// expanding load 3 -> 4
template<class T, order Order> struct endian_load_impl<T, 4, Order, 3, order::little>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 4 ];
tmp[0] = p[0];
tmp[1] = p[1];
tmp[2] = p[2];
tmp[3] = std::is_signed<T>::value && ( p[2] & 0x80 )? 0xFF: 0x00;
return boost::endian::endian_load<T, 4, order::little>( tmp );
}
};
template<class T, order Order> struct endian_load_impl<T, 4, Order, 3, order::big>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 4 ];
tmp[0] = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
tmp[1] = p[0];
tmp[2] = p[1];
tmp[3] = p[2];
return boost::endian::endian_load<T, 4, order::big>( tmp );
}
};
// expanding load 1 -> 8
template<class T, order Order> struct endian_load_impl<T, 8, Order, 1, order::little>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
tmp[0] = p[0];
tmp[1] = fill;
tmp[2] = fill;
tmp[3] = fill;
tmp[4] = fill;
tmp[5] = fill;
tmp[6] = fill;
tmp[7] = fill;
return boost::endian::endian_load<T, 8, order::little>( tmp );
}
};
template<class T, order Order> struct endian_load_impl<T, 8, Order, 1, order::big>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
tmp[0] = fill;
tmp[1] = fill;
tmp[2] = fill;
tmp[3] = fill;
tmp[4] = fill;
tmp[5] = fill;
tmp[6] = fill;
tmp[7] = p[0];
return boost::endian::endian_load<T, 8, order::big>( tmp );
}
};
// expanding load 2 -> 8
template<class T, order Order> struct endian_load_impl<T, 8, Order, 2, order::little>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[1] & 0x80 )? 0xFF: 0x00;
tmp[0] = p[0];
tmp[1] = p[1];
tmp[2] = fill;
tmp[3] = fill;
tmp[4] = fill;
tmp[5] = fill;
tmp[6] = fill;
tmp[7] = fill;
return boost::endian::endian_load<T, 8, order::little>( tmp );
}
};
template<class T, order Order> struct endian_load_impl<T, 8, Order, 2, order::big>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
tmp[0] = fill;
tmp[1] = fill;
tmp[2] = fill;
tmp[3] = fill;
tmp[4] = fill;
tmp[5] = fill;
tmp[6] = p[0];
tmp[7] = p[1];
return boost::endian::endian_load<T, 8, order::big>( tmp );
}
};
// expanding load 3 -> 8
template<class T, order Order> struct endian_load_impl<T, 8, Order, 3, order::little>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[2] & 0x80 )? 0xFF: 0x00;
tmp[0] = p[0];
tmp[1] = p[1];
tmp[2] = p[2];
tmp[3] = fill;
tmp[4] = fill;
tmp[5] = fill;
tmp[6] = fill;
tmp[7] = fill;
return boost::endian::endian_load<T, 8, order::little>( tmp );
}
};
template<class T, order Order> struct endian_load_impl<T, 8, Order, 3, order::big>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
tmp[0] = fill;
tmp[1] = fill;
tmp[2] = fill;
tmp[3] = fill;
tmp[4] = fill;
tmp[5] = p[0];
tmp[6] = p[1];
tmp[7] = p[2];
return boost::endian::endian_load<T, 8, order::big>( tmp );
}
};
// expanding load 4 -> 8
template<class T, order Order> struct endian_load_impl<T, 8, Order, 4, order::little>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[3] & 0x80 )? 0xFF: 0x00;
tmp[0] = p[0];
tmp[1] = p[1];
tmp[2] = p[2];
tmp[3] = p[3];
tmp[4] = fill;
tmp[5] = fill;
tmp[6] = fill;
tmp[7] = fill;
return boost::endian::endian_load<T, 8, order::little>( tmp );
}
};
template<class T, order Order> struct endian_load_impl<T, 8, Order, 4, order::big>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
tmp[0] = fill;
tmp[1] = fill;
tmp[2] = fill;
tmp[3] = fill;
tmp[4] = p[0];
tmp[5] = p[1];
tmp[6] = p[2];
tmp[7] = p[3];
return boost::endian::endian_load<T, 8, order::big>( tmp );
}
};
// expanding load 5 -> 8
template<class T, order Order> struct endian_load_impl<T, 8, Order, 5, order::little>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[4] & 0x80 )? 0xFF: 0x00;
tmp[0] = p[0];
tmp[1] = p[1];
tmp[2] = p[2];
tmp[3] = p[3];
tmp[4] = p[4];
tmp[5] = fill;
tmp[6] = fill;
tmp[7] = fill;
return boost::endian::endian_load<T, 8, order::little>( tmp );
}
};
template<class T, order Order> struct endian_load_impl<T, 8, Order, 5, order::big>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
tmp[0] = fill;
tmp[1] = fill;
tmp[2] = fill;
tmp[3] = p[0];
tmp[4] = p[1];
tmp[5] = p[2];
tmp[6] = p[3];
tmp[7] = p[4];
return boost::endian::endian_load<T, 8, order::big>( tmp );
}
};
// expanding load 6 -> 8
template<class T, order Order> struct endian_load_impl<T, 8, Order, 6, order::little>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[5] & 0x80 )? 0xFF: 0x00;
tmp[0] = p[0];
tmp[1] = p[1];
tmp[2] = p[2];
tmp[3] = p[3];
tmp[4] = p[4];
tmp[5] = p[5];
tmp[6] = fill;
tmp[7] = fill;
return boost::endian::endian_load<T, 8, order::little>( tmp );
}
};
template<class T, order Order> struct endian_load_impl<T, 8, Order, 6, order::big>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
tmp[0] = fill;
tmp[1] = fill;
tmp[2] = p[0];
tmp[3] = p[1];
tmp[4] = p[2];
tmp[5] = p[3];
tmp[6] = p[4];
tmp[7] = p[5];
return boost::endian::endian_load<T, 8, order::big>( tmp );
}
};
// expanding load 7 -> 8
template<class T, order Order> struct endian_load_impl<T, 8, Order, 7, order::little>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[6] & 0x80 )? 0xFF: 0x00;
tmp[0] = p[0];
tmp[1] = p[1];
tmp[2] = p[2];
tmp[3] = p[3];
tmp[4] = p[4];
tmp[5] = p[5];
tmp[6] = p[6];
tmp[7] = fill;
return boost::endian::endian_load<T, 8, order::little>( tmp );
}
};
template<class T, order Order> struct endian_load_impl<T, 8, Order, 7, order::big>
{
inline T operator()( unsigned char const * p ) const BOOST_NOEXCEPT
{
BOOST_ENDIAN_STATIC_ASSERT( std::is_integral<T>::value || std::is_enum<T>::value );
unsigned char tmp[ 8 ];
unsigned char fill = std::is_signed<T>::value && ( p[0] & 0x80 )? 0xFF: 0x00;
tmp[0] = fill;
tmp[1] = p[0];
tmp[2] = p[1];
tmp[3] = p[2];
tmp[4] = p[3];
tmp[5] = p[4];
tmp[6] = p[5];
tmp[7] = p[6];
return boost::endian::endian_load<T, 8, order::big>( tmp );
}
};
} // namespace detail
} // namespace endian
} // namespace boost
#endif // BOOST_ENDIAN_DETAIL_ENDIAN_LOAD_HPP_INCLUDED