Applications
Bitwise operations are necessary particularly in lower-level programming such as writing device drivers, low-level graphics, communications protocol packet assembly, and decoding.
Although machines often have efficient built-in instructions for performing arithmetic and logical operations, in fact, all these operations can be performed by combining the bitwise operators and zero-testing in various ways.
For example, here is a pseudocode example showing how to multiply two arbitrary integers a and b (a greater than b) using only bitshifts and addition:
c := 0
while b ≠ 0 if (b and 1) ≠ 0 c := c + a left shift a by 1 right shift b by 1
return c
This implementation of ancient Egyptian multiplication, like most multiplication algorithms, involves bitshifts. In turn, even addition can be written using just bitshifts and zero-testing:
c := b and a
while a ≠ 0 c := b and a b := b xor a left shift c by 1 a := c
return b
Read more about this topic: Bitwise Operation