proper way to handle maker notes

[Rafael Espíndola]

For decompressing NEF files I need to read the decompression curve. I
am not sure I am using the API the best I way. What I currently have
is:

		void NEFFile::_getCompressionCurve(std::vector<uint8_t>& v)
		{
			IFDDir::Ref dir = _locateExifIfd();
			assert(dir);
			IFDEntry::Ref maker_ent = dir->getEntry(IFD::EXIF_TAG_MAKER_NOTE);
			assert(maker_ent);


			uint32_t off = maker_ent->offset();
			uint32_t base = off + 10;

			IFDDir::Ref ref(new IFDDir(base + 8, *m_container));
			ref->load();
			IFDEntry::Ref curve = ref->getEntry(0x0096);
			assert(curve);

			size_t size = curve->count();

			std::vector<uint8_t> temp(size);

			size_t read = m_container->fetchData(&temp[0],
												 base + curve->offset(),
												 size);
			assert(read == size);

			v.swap(temp);
		}

Other then proper error checking and not hard coding constants, is
this the proper way to read something from the MakerNote?

Cheers,
Rafael