C++ class for reading/writing of new MCPE 1.3 paletted blocks - https://gist.github.com/Tomcc/a96af509e275b1af483b25c543cfbf37

PalettedBlockStateStorage (sampl).cpp

template <unsigned int NBitsPerBlock, typename Word = unsigned int>
	struct PalettedBlockStateStorage {

		static const int wordByteSize = sizeof(Word)/*4*/;
		static const int wordBitSize = wordByteSize * 8;

		static const byte blocksPerWord = NAIVE_FLOOR(wordBitSize / NBitsPerBlock);
		static const byte paddingPerWord = wordBitSize % NBitsPerBlock;

		static const int wordsCount = NAIVE_CEIL(4096.0 / blocksPerWord);

		Word blockArrayI[wordsCount];

		constexpr int readBits(const Word &what, int bitoff) {
			return (what >> bitoff) & ((1 << NBitsPerBlock) - 1);
		}

		constexpr void writeBits(Word &what, int bitoff, int data) {
			what &= ~(((1 << NBitsPerBlock) - 1) << bitoff);
			what |= (data & ((1 << NBitsPerBlock) - 1)) << bitoff;
		}

		constexpr void getIndex(byte x, byte y, byte z, int &index, int &offset) {
			// safety checks
			x = x & 0xf;
			y = y & 0xf;
			z = z & 0xf;

			index = floor(((x << 8) | (z << 4) | y) / blocksPerWord);
			offset = (((x << 8) | (z << 4) | y) % blocksPerWord) * NBitsPerBlock;
		}

		constexpr int getBlockStateAt(byte x, byte y, byte z) {
			int index, offset;
			getIndex(x, y, z, index, offset);
			return readBits(blockArrayI[index], offset);
		}


		constexpr void setBlockStateAt(byte x, byte y, byte z, int data) {
			int index, offset;
			getIndex(x, y, z, index, offset);
			writeBits(blockArrayI[index], offset, data);
		}
	};