[psyang]

Originally Posted by GGG

Spoiler!

isn’t that just Twos compliment for creating negative binary numbers

Spoiler!

No, 2's complement is the inverse of the binary representation plus 1. That way, a + 2's complement a = 0 (ignoring overflow bit)

f is reversing the order of the bits.

As an example:

f(1011) = 1101
f(1011) + 1011 = 1101 + 1011 = 1 1000

if g is the 2's complement function, then
g(1011) = 0101
g(1011) + 1011 = 0101 + 1011 = 1 0000