Thank you for your question.
We want to note that you will need to check if your coordinate is negative or positive.
To determine if the coordinate is negative, convert it to binary format and check the very first bit. If it is 0, coordinate is positive, if it is 1, coordinate is negative.
20 9C CA 80 converted to BIN:
00100000 10011100 11001010 10000000 first bit is 0, which means coordinate is positive converted to DEC:
547146368. For more information see two‘s complement arithmetic.
Please let us know if you will have more questions.