Addition and Subtraction blocks in simulink performs integer addition and subtraction, not bitwise.
What is your expectation for bitwise operation ?
Addition:
0 0 --> 0
0 1 --> 1
1 0 --> 1
1 1 --> ? What about carry ?
Subtraction:
0 0 --> 0
0 1 --> ? Borrow ?
1 0 --> 1
1 1 --> 0
Depending upon your expectation, you can extracts the bits from your integer and construct the logic using Logical blocks to perform the bitwise operation.
