Bitwise Operators

Bitwise OR => to "set" or "turn on" a "flag"

Bitwise AND => used to check the state(0/1) of a flag in your flags variable

Bitwise XOR => used to toggle the flag bits of a MASK in your flags variable

Bitwise NOT => used to toggle the bits

Left Shift => Multiply 2

Right Shift => Divide by 2

ref:

http://c-faq.com/~scs/cclass/int/sx4ab.html

http://analgorithmaday.blogspot.com/2011/06/mis-conceptions-with-bitwise-operators.html

http://www.robsearles.com/2009/12/02/bitwise-operators-used-for-flagging-items-part-1/