1’s complement
0 1 2 3 -3 -2 -1 -0
------------------>
- naming rationale: sum
x + -x= all 1s - representation:
sX = (-1)^s * ~X- first bit represents sign (
s) - all other bits are flipped binary representation of (
~X)
- first bit represents sign (
- conversion: flip all bits
0000 1011 = 11
1111 0100 = -11
---------
1111 1111 = -0
- Pros:
- Quick conversion
- Cons:
- 2 zeros: all ones (-0) and all zeros (+0)
- arithmetic is expensive