Merge branch 'main' of https://github.com/supleed2/AM04_CPU into main

rtl/mips_cpu_control.v

@@ -47,17 +47,30 @@ Memtoreg:
 Aluop:
 0: r-type instructions
 1: <0 
+   -BLTZAL BLTZ
 2: >=0
+   -BGEZAL BGEZ
 3: =0
+   -BEQ
 4: =/=0
+   -BNE
 5: <=0
+   -BLEZ
 6: >0
+   -BGTZ
 7: add
+   -ADDIU
+   -all load and store instructions
 8: slt (signed)
+   -STLI
 9: slt (unsigned)
+   -STLIU
 10: and
+    -ANDI
 11: or
+    -ORI
 12: xor
+    -XORI
 */
 
 //Commented signals represents dont care(x)

rtl/mips_cpu_harvard.v

@@ -75,13 +75,15 @@ control control( //control flags block
 );
 
 regfile regfile(
-.readreg1(rs),
+.clk(clk), //clock input for triggering write port
-.readreg2(rt),
+.readreg1(rs), //read port 1 selector
-.writereg(rd),
+.readreg2(rt), //read port 2 selector
-.writedata(writeback),
+.writereg(rd), //write port selector
-.regwrite(RegWrite),
+.writedata(writeback), //write port input data
-.readdata1(read_data1),
+.regwrite(RegWrite), //enable line for write port
-.readdata2(read_data2),
+.opcode(opcode), //opcode input for controlling partial load weirdness
+.readdata1(read_data1), //read port 1 output
+.readdata2(read_data2), //read port 2 output
 .regv0(register_v0) //debug output of $v0 or $2 (first register for returning function results
 );
 

rtl/mips_cpu_regfile.v

@@ -0,0 +1,66 @@
+module regfile(
+input logic clk, //clock input for triggering write port
+input logic[4:0] readreg1, //read port 1 selector
+input logic[4:0] readreg2, //read port 2 selector
+input logic[4:0] writereg, //write port selector
+input logic[31:0] writedata, //write port input data
+input logic regwrite, //enable line for write port
+input[5:0] opcode, //opcode input for controlling partial load weirdness
+output logic[31:0] readdata1, //read port 1 output
+output logic[31:0] readdata2, //read port 2 output
+output logic[31:0] regv0 //debug output of $v0 or $2 (third register in file/ first register for returning function results)
+);
+
+reg[31:0] memory [31:0]; //32 register slots, 32-bits wide
+
+initial begin
+	integer i; //Initialise to zero by default
+    for (i = 0; i < 31; i++) begin
+        memory[i] = 0;
+    end
+end
+
+assign regv0 = memory[2]; //assigning debug $v0 line to $2 of memory
+
+always_comb begin
+	readdata1 = memory[readreg1]; //combinatorially output register value based on read port 1 selector
+	readdata2 = memory[readreg2]; //combinatorially output register value based on read port 2 selector
+end
+
+always_ff @(posedge clk) begin
+	if (regwrite) begin
+		case (opcode)
+			6'b100000: begin //lb, load byte
+				memory[writereg] <= {{24{writedata[7]}}, writedata[7:0]};
+			end
+			6'b100100: begin //lbu, load byte unsigned
+				memory[writereg] <= {{24{1'b0}}, writedata[7:0]};
+			end
+			6'b100001: begin //lh, load half-word
+				memory[writereg] <= {{16{writedata[15]}}, writedata[15:0]};
+			end
+			6'b100101: begin //lhu, load half-word unsigned
+				memory[writereg] <= {{16{1'b0}}, writedata[15:0]};
+			end
+			6'b100010: begin //lwl, load word left
+				case (readdata1[1:0])
+					2'b00: memory[writereg][31:24] <= writedata[7:0];
+					2'b01: memory[writereg][31:16] <= writedata[15:0];
+					2'b10: memory[writereg][31:8] <= writedata[23:0];
+					2'b11: memory[writereg][31:0] <= writedata[31:0];
+				endcase // readdata1[1:0]
+			end
+			6'b100110: begin //lwr, load word right
+				case (readdata1[1:0])
+					2'b00: memory[writereg][31:0] <= writedata[31:0];
+					2'b01: memory[writereg][23:0] <= writedata[31:8];
+					2'b10: memory[writereg][15:0] <= writedata[31:16];
+					2'b11: memory[writereg][7:0] <= writedata[31:24];
+				endcase // readdata1[1:0]
+			end
+			default: memory[writereg] <= writedata; //most instructions
+		endcase // opcode
+	end
+end
+
+endmodule : regfile