Write a program to implement the checksum method.

The implementation has two parts:

a. Calculating the checksum at the sender

b. Verifying the checksum at the receiver

Calculating the checksum at the sender

Inputs: 4 data each consist ing of 16 - bit (binary)

Output: Checksum of 16 - bit (binary)

Example:

http://mathforum.org/library/drmath/view/54379.html

For example, suppose

we have the

following data. I separate the

data into groups of 4 bits only for readability.

1000 0110 0101 1110

1010 1100 0110 0000

0111 0001 0010 1010

1000 0001 1011 0101

First, we add the 16

-

bit values 2 at a time:

1000 0110 0101 1110 First 16

-

bit value

+ 1010 1100 0110 0000 Second 16

-

bit value

---------------------

1 0011 0010 1011 1110 Produced a carry

-

out, which gets added

+

\

----------------

> 1 back into L

S

b

---------------------

0011 0010 1011 1111

+ 0111 0001 0010 1010 Third 16

-

bit value

---------------------

0 1010 0011 1110 1001 No carry to swing around (**)

+ 1000 0001 1011 0101 Fourth 16

-

bit value

---------------------

1 0010 0101 1001 1110 Produ

ced a carry

-

out, which gets added

+

\

----------------

> 1 back into L

S

b

---------------------

0010 0101 1001 1111 Our "one's complement sum"

(**) Note that we could "swing around" the carry

out of 0, but adding

0 back into the LSb has no

e

ffect on the sum. (But technically, that's

what the checksum generator does.)

Then we have to take the one's complement of the sum. We do this by

simply inverting all the bits in the final result from above:

0010 01

01 1001 1111 Our "one's complement sum"

1101 1010 0110 0000 The "one's complement"

Therefore, the checksum

generated from the given data

would be 1101 1010 0110 0000.

Verifying the checksum at the receiver

Inputs: 4 data each is consis t ing of 16 - bit and their 16 - bit checksum

Output: Checksum for 4 data each is consist ing of 16 - bit and their 16 - bit checksum

If checksum is equal to 0s, your data is not corrupted

If checksum is not equal 0s, your data is corrupted