(a) Add the MIPS instruction jal (jump and link) to the MIPS subset Verilog code (Figure 9-8). jal is used for procedure calls. jal jumpaddr puts the return address (PC + 1) in register file $31 and then goes to jumpaddr for the next instruction. (The original MIPS used (PC + 4) and jumpaddr*4; however, because the implementation in Chapter 9 uses word addressing instead of byte addressing, the 4 is replaced with 1.) The jal instruction uses the J format; therefore, the first 6 bits are the opcode (3) and the remaining 26 bits are jumpaddr. Make as few changes to the Verilog code as necessary.
(b) Create a test bench to test this instruction.