Single cycle code from on Harris and Harris second edition

This code is taken from Digital Design and Computer Architecture by Harris and Harris.

What did I change in this repo?

Three changes are made to the code in this repo:

1. Implementing the lb instruction. It is an I-type instruction which is the same as lw but it stores the first byte seen on the given address. The Opcode for this instruction is 100000.
2. Implementing the jr instruction. This instruction loads the $ra into $pc. It's an r-type instruction. The Opcode and funct for this instruction in order are 000000 and 001000.
3. Implementing the jalr instruction.

How to test the code?

There is a test bench file named testbench.sv and a file memfile.dat which holds the program to be tested. The assembly program which is equivalent of the machine codes written in memfile.dat is in the file instructions.txt. Consider reading testbench.sv and instructions.txt in order to figure out how the testing is going on.