Question on How the Checksum is Computed, please help!

[marjon]

I would like to ask on how the checksum is computed?
This was the line I found in gnokii, module FBxx_RX_StateMachine(char 
rx_byte):
----> if (checksum[0] == checksum[1])
But what is the received bytes were like this:
:1e:0c:00:7f:00:02:d1:80:cf:f1

I mean, I get checksum[0] = 0xcf & checksum[1] = f1
But they would never be equal right? so the program would not pass
through the  if statement?  But as I understand, it does? how is this?
Please explain.

Marjon