Calculating CRC 16 in java

[polo rao]

Hi , i need to do a project which wants me to calculate CRC 16 in java without using lookup table
Can anybody guide me about how we code for CRC16 in java
I know Java has CRC32 package but i dont see how it can help me

Thanks in advance

[polo rao]

Can anyone please help me. I was really pissed off , trying to figure out how to do it all night.and i have to submit my code by monday
Any help will be appreciated
Thanks

[Ulf Dittmer]

What do you have so far? Do you understand the algorithm for CRC in general? If so, what stops you from implementing it? If not, do you have material that explains it?

[Rob Prime]

I would have said to check the source of CRC32, but its important methods are native.

Using Google, I found two results you may be able to use. The first one uses a lookup table though, but the seecond one surely does not.

[polo rao]

Thanks Rob for your reply.
I wanted to know , in the 2nd link

 private static	short polynomial=(short)0x8005   

Isnt this line initialising a generator polynomial , to create a lookup table in program.
I dont know if it really does , but was just puzzled about what is its use in program
Thanks

[Henry Wong]

Isnt this line initialising a generator polynomial , to create a lookup table in program.
I dont know if it really does , but was just puzzled about what is its use in program

The reason lookup tables are *not* allowed in a homework assignment is because it is possible to develop the CRC code without knowing how CRC works. And the purpose of the assignment is to learn how CRC works.

Anyway, do you know how CRC works? If you don't, I recommend that you do that first -- coding by cut and paste may get you done with the assignment, but you don't really learn much.

Henry