| is binary OR like the OR gate
& is binary AND like the AND gate
>>8 shifts variable 8 bits to the right
in c instead of saying x = x & 0x0ff you can say x &= 0x0ff (less typing)
(-TC_100ms >> 8) is bad programing practice, i dont know which has precedence the - or the >> but i think -TC_100ms means 2's complement of TC_100ms.
integers are 16 bits if you want to test the lower byte of integer you and it with 0x0ff , if you want to test the upper byte of integer you shift it right 8 bits >> 8.
Hope this helps
Good luck
Mahmood