Question

I’m reading some bytes out of a byte stream and they look like this:

OUTPUT:
48 -84 -79 -84 -73 -79 46 48 -84

SHOULD BE:
48  44  49  44  55  49 46 48  44

I’d like to turn these into ascii characters but those negitive symbols are confusing me. This makes me think I don’t understand signed bytes. What on earth am I doing wrong here?

Answer 1

Looks like the highest bit is used as a parity bit, while your code assumes it is a sign bit.

• 48 = 011 0000 : 2 bits set -> add 0
  -> 0011 0000 = 48
• 44 = 010 1100 : 3 bits set -> add 1
  -> 1010 1100 = -84
• 49 = 011 0001 : 3 bits set -> add 1 -> 1011 0001 = -79
• and so on…

Solution: mask away the highest bit by using (value & 0x7f).