RFC.hpp

			max_bytes -= diff;
		}
		auto tmp_start = start;
		uint64_t bytes_written = de_interleaving (tmp_start, end, max_bytes,
																	new_skip);
		written += bytes_written;
		uint64_t bytes_and_skip = new_skip + bytes_written;
		new_skip = bytes_and_skip %
					sizeof(typename std::iterator_traits<Fwd_It>::value_type);
		if (bytes_written == 0)
			return written;
		//new_skip = block_size (sbn) %
		//			sizeof(typename std::iterator_traits<Fwd_It>::value_type);
		// if we ended decoding in the middle of a Fwd_It, do not advance
		// start too much, or we will end up having additional zeros.
		if (new_skip == 0) {
			start = tmp_start;
		} else {
			uint64_t it_written = bytes_and_skip /
					sizeof(typename std::iterator_traits<Fwd_It>::value_type);
			// RaptorQ handles at most 881GB per rfc, so
			// casting uint64 to int64 is safe
			// we can not do "--start" since it's a forward iterator
			start += std::max (static_cast<int64_t> (0),
										static_cast<int64_t> (it_written - 1));
		}
	}
	return written;
}

template <typename In_It, typename Fwd_It>
uint64_t Decoder<In_It, Fwd_It>::decode_block_bytes (Fwd_It &start,
															const Fwd_It end,
															const uint8_t skip,
															const uint8_t sbn)
{
	if (sbn >= _blocks)
		return 0;

	std::shared_ptr<RaptorQ__v1::Impl::Raw_Decoder<In_It>> dec_ptr = nullptr;
	std::unique_lock<std::mutex> lock (_mtx);
	auto it = decoders.find (sbn);

	if (it == decoders.end())
		return 0;	// did not receiveany data yet.

	if (use_pool) {
		dec_ptr = it->second.dec;
		lock.unlock();
		if (!dec_ptr->ready())
			return 0;	// did not receive enough data, or could not decode yet.
	} else {
		dec_ptr = it->second.dec;
		lock.unlock();
		if (!dec_ptr->ready()) {
			if (!dec_ptr->can_decode())
				return 0;
			RaptorQ__v1::Work_State keep_working =
										RaptorQ__v1::Work_State::KEEP_WORKING;
			dec_ptr->decode (&keep_working);
			if (!dec_ptr->ready())
				return 0;
		}
	}
	// decoder has decoded the block

	Impl::De_Interleaver<Fwd_It> de_interleaving (dec_ptr->get_symbols(),
													_sub_blocks, _alignment);
	uint64_t max_bytes = block_size (sbn);
	if (sbn == (blocks() - 1)) {
		// size of the data (_size) is different from the sum of the size of
		// all blocks. get the real size, so we do not write more.
		// we obviously need to consider this only for the last block.
		uint64_t all_blocks = 0;
		for (uint8_t id = 0; id < blocks(); ++id)
			all_blocks += block_size (sbn);
		const uint64_t diff = all_blocks - _size;
		max_bytes -= diff;
	}
	return de_interleaving (start, end, max_bytes, skip);
}

template <typename In_It, typename Fwd_It>
std::pair<size_t, uint8_t> Decoder<In_It, Fwd_It>::decode_aligned (
														Fwd_It &start,
														const Fwd_It end,
														const uint8_t skip)
{
	const uint64_t bytes = decode_bytes (start, end, skip);
	const uint64_t skip_and_bytes = skip + bytes;
	const uint64_t iterators = skip_and_bytes /
					sizeof(typename std::iterator_traits<Fwd_It>::value_type);
	const uint8_t new_skip = skip_and_bytes %
					sizeof(typename std::iterator_traits<Fwd_It>::value_type);
	return {iterators, new_skip};
}

template <typename In_It, typename Fwd_It>
std::pair<size_t, uint8_t> Decoder<In_It, Fwd_It>::decode_block_aligned (
														Fwd_It &start,
														const Fwd_It end,
														const uint8_t skip,
														const uint8_t sbn)
{
	const uint64_t bytes = decode_block_bytes (start, end, skip, sbn);
	const uint64_t skip_and_bytes = skip + bytes;
	const uint64_t iterators = skip_and_bytes /
					sizeof(typename std::iterator_traits<Fwd_It>::value_type);
	const uint8_t new_skip = skip_and_bytes %
					sizeof(typename std::iterator_traits<Fwd_It>::value_type);
	return {iterators, new_skip};
}

template <typename In_It, typename Fwd_It>
uint64_t Decoder<In_It, Fwd_It>::bytes() const
{
	return _size;
}

template <typename In_It, typename Fwd_It>
uint8_t Decoder<In_It, Fwd_It>::blocks() const
{
	return static_cast<uint8_t> (part.num (0) + part.num (1));
}

template <typename In_It, typename Fwd_It>
uint32_t Decoder<In_It, Fwd_It>::block_size (const uint8_t sbn) const
{
	if (sbn < part.num (0)) {
		return part.size (0) * _symbol_size;
	} else if (sbn - part.num (0) < part.num (1)) {
		return part.size (1) * _symbol_size;
	}
	return 0;
}

template <typename In_It, typename Fwd_It>
uint16_t Decoder<In_It, Fwd_It>::symbol_size() const
{
	return _symbol_size;
}
template <typename In_It, typename Fwd_It>
uint16_t Decoder<In_It, Fwd_It>::symbols (const uint8_t sbn) const
{
	if (sbn < part.num (0)) {
		return part.size (0);
	} else if (sbn - part.num (0) < part.num (1)) {
		return part.size (1);
	}
	return 0;
}

}   // namespace Impl
}	// namespace RFC6330__v1