バイトストリームを容易に扱うための ibytestream。MIT ライセンスで。

ibytestream.hpp

#pragma once
#include <istream>

namespace mntone { namespace utility {

	class ibytestream
		: std::basic_istream<uint8_t>
	{
	public:
		using baseistream = std::basic_istream<uint8_t>;

		uint8_t readuint8()
		{
			uint8_t ret( 0 );
			baseistream::read( &ret, 1 );
			return ret;
		}

		uint16_t readuint16be()
		{
			uint16_t ret( 0 );
			{
				std::array<uint8_t, 2> buf;
				baseistream::read( buf.data(), 2 );
				convert_big_endian( buf, &ret );
			}
			return ret;
		}	
		uint16_t readuint16le()
		{
			uint16_t ret( 0 );
			{
				std::array<uint8_t, 2> buf;
				baseistream::read( buf.data(), 2 );
				convert_little_endian( buf, &ret );
			}
			return ret;
		}
		uint16_t readuint16()
		{
			return readuint16le();
		}

		uint32_t readuint24be()
		{
			uint32_t ret( 0 );
			{
				std::array<uint8_t, 3> buf;
				baseistream::read( buf.data(), 3 );
				convert_big_endian( buf, &ret );
			}
			return ret;
		}
		uint32_t readuint24le()
		{
			uint32_t ret( 0 );
			{
				std::array<uint8_t, 3> buf;
				baseistream::read( buf.data(), 3 );
				convert_little_endian( buf, &ret );
			}
			return ret;
		}
		uint32_t readuint24()
		{
			return readuint24le();
		}

		uint32_t readuint32be()
		{
			uint32_t ret( 0 );
			{
				std::array<uint8_t, 4> buf;
				baseistream::read( buf.data(), 4 );
				convert_big_endian( buf, &ret );
			}
			return ret;
		}
		uint32_t readuint32le()
		{
			uint32_t ret( 0 );
			{
				std::array<uint8_t, 4> buf;
				baseistream::read( buf.data(), 4 );
				convert_little_endian( buf, &ret );
			}
			return ret;
		}
		uint32_t readuint32()
		{
			return readuint32le();
		}


	private:
		template<size_t T>
		void convert_big_endian( std::array<uint8_t, T> data, void* const dest )
		{
			auto ptr = reinterpret_cast<const uint8*>( first ) + size;
			auto pdest = reinterpret_cast<uint8*>( dest );
    
			for( ; first != ptr; ++pdest )
			{
				*pdest = *--ptr;
			}
		}

		template<size_t T>
		void convert_little_endian( std::array<uint8_t, T> data, void* const dest )
		{
			memcpy( dest, first, size );
		}
	};
	
} }