Update regfile and harvard to enable register reset

rtl/mips_cpu_harvard.v

@@ -117,6 +117,7 @@ mips_cpu_control control( //instance of the 'mips_cpu_control' module called 'co
 mips_cpu_regfile regfile(
 //Inputs to refile
     .clk(clk), //clock input for triggering write port
+    .rst(reset),
     .readreg1(in_readreg1), //read port 1 selector
     .readreg2(in_readreg2), //read port 2 selector
     .writereg(in_writereg), //write port selector

rtl/mips_cpu_regfile.v

@@ -1,5 +1,6 @@
 module mips_cpu_regfile(
 input logic clk, //clock input for triggering write port
+input logic rst,
 input logic[4:0] readreg1, //read port 1 register selector
 input logic[4:0] readreg2, //read port 2 register selector
 input logic[4:0] writereg, //write port register selector
@@ -26,6 +27,13 @@ assign regv0 = memory[2]; //assigning debug $v0 line to $2 of memory
 assign readdata1 = memory[readreg1]; //combinatorially output register value based on read port 1 selector
 assign readdata2 = memory[readreg2]; //combinatorially output register value based on read port 2 selector
 
+always_ff @(posedge rst) begin
+	integer i; //Initialise to zero when reset
+    for (i = 0; i < 32; i++) begin
+        memory[i] = 0;
+    end
+end
+
 always_ff @(negedge clk) begin
 	if (writereg == 5'b00000) begin
 		// skip writing if rd is $0