translate a 10-digit barcode to and from multiple formats
http://briangallimore.com/barcodeconverter/
1 to 10 digits (numbers are typical, but any ASCII value will work)
change any value to calculate new result
each character is stored in one 8-bit register (but only uses 7 bits)
upper 8 bits is the first character and the lower 8 bits is the second character
The first 2 registers each contain 4 characters stored as ASCII values, the 3rd register contains 2 characters
(this format always wastes 16-bits of data storage)
The first 5 digits are stored in the first register, second 5 digits are stored in the second register
(only uses 17 bits for each register when the barcode is numerical value only)