Merge pull request #2 from supleed2/bus_wrapper

Merge Bus Version and updated testcases to Main

.gitignore

@@ -3,5 +3,6 @@ exec/*
 *.log.txt
 *.out.txt
 mips_cpu_harvard.vcd
+mips_cpu_bus.vcd
 .DS_Store
 inputs/.DS_Store

inputs/sb/sb-1.txt

@@ -1,7 +1,6 @@
 3C041234
 34045678
-3C05BFC0
+3405101C
-3405001C
 A0A40000
 80A20000
 00000008

inputs/sh/sh-1.txt

@@ -1,7 +1,6 @@
 3C041234
 34045678
-3C05BFC0
+3405101C
-3405001C
 A4A40000
-84A40000
+84A20000
 00000008

inputs/sh/sh-2.ref.txt

@@ -0,0 +1 @@
+22136

inputs/sh/sh-2.txt

@@ -0,0 +1,6 @@
+3C041234
+34045678
+3405101C
+A4A40000
+8CA20000
+00000008

reference/reference.txt

@@ -662,16 +662,14 @@ register_v0 = 65535
 
 lui $4, 0x1234
 ori $4, $0, 0x5678
-lui $5, 0xBFC0
+ori $5, $0, 0x101C
-ori $5, $0, 0x001C
 sb $4, 0($5)
 lb $2, 0($5)
 jr $0
 
 3C041234
 34045678
-3C05BFC0
+3405101C
-3405001C
 A0A40000
 80A20000
 00000008
@@ -682,18 +680,32 @@ register_v0 = 0x00000078
 
 lui $4, 0x1234
 ori $4, $0, 0x5678
-lui $5, 0xBFC0
+ori $5, $0, 0x101C
-ori $5, $0, 0x001C
 sh $4, 0($5)
 lh $2, 0($5)
 jr $0
 
 3C041234
 34045678
-3C05BFC0
+3405101C
-3405001C
 A4A40000
-84A40000
+84A20000
+00000008
+
+-Load Entire Word Version
+
+lui $4, 0x1234
+ori $4, $0, 0x5678
+ori $5, $0, 0x101C
+sh $4, 0($5)
+lw $2, 0($5)
+jr $0
+
+3C041234
+34045678
+3405101C
+A4A40000
+8CA20000
 00000008
 
 register_v0 = 0x00005678

rtl/mips_cpu_bus.v

@@ -0,0 +1,231 @@
+module mips_cpu_bus(
+    /* Standard signals */
+    input logic clk,
+    input logic reset,
+    output logic active,
+    output logic[31:0] register_v0,
+
+    /* Avalon memory mapped bus controller (master) */
+    output logic[31:0] address,
+    output logic write,
+    output logic read,
+    input logic waitrequest,
+    output logic[31:0] writedata,
+    output logic[3:0] byteenable,
+    input logic[31:0] readdata
+);
+
+logic[1:0] state; // current state of cpu within cycle
+logic[1:0] n_state; // state to be set at next clk edge
+logic[31:0] instr_reg; // instruction register / single-word cache for current instruction
+logic clk_internal; // modulated clock to be passed to harvard cpu
+logic[31:0] harvard_instr_address; // instr addr from pc
+logic harvard_read; // harvard cpu read flag
+logic harvard_write; // harvard cpu write flag
+logic[31:0] harvard_data_address; // data addr from ALU
+logic[31:0] harvard_readdata; // <= data read from Avalon MM Device
+logic[31:0] harvard_writedata; // data to be written to Avalon MM Device
+logic[3:0] write_byteenable; // byteenable calculator for partial write
+logic clk_state; // make sure posedge and negedge of clk do not occur repeatedly
+logic partial_write; // flag to control datapath when doing a partial write
+logic[31:0] partial_writedata; // modified data for partial writes (StoreHalfword or StoreByte)
+logic[31:0] write_data_address; // modified data address for partial writes
+logic clk_enable; // unused floating wire
+
+initial begin
+    clk_internal = 1'b0;
+    n_state = 2'b00;
+    state = 2'b00;
+    instr_reg = 32'h00000000;
+    address = 32'h00000000;
+    write = 1'b0;
+    read = 1'b0;
+    writedata = 32'h00000000;
+    byteenable = 4'b0000;
+    clk_state = 0;
+end
+
+always_ff @(negedge reset) begin // kickstart clock after reset
+    clk_internal <= 1'b1;
+    state <= 2'b00;
+end
+
+always_ff @(posedge clk) begin // CLK Rising Edge
+    if (!waitrequest && !clk_state) begin
+        case (n_state)
+            2'b00: begin // fetch
+                clk_internal <= 1'b1;
+                state <= 2'b00;
+            end
+            2'b01: begin // execute
+                state <= 2'b01;
+                instr_reg <= readdata;
+            end
+            2'b10: begin // read
+                state <= 2'b10;
+            end
+            2'b11: begin // write
+                state <= 2'b11;
+            end
+        endcase // state
+    end
+    clk_state <= 1'b1;
+end
+
+always_ff @(negedge clk) begin // CLK Falling Edge
+    if (!waitrequest && clk_state) begin
+        case (state)
+            2'b00: begin // nothing happens on fetch negedge
+            end
+            2'b01: begin // execute negedge
+                if (!harvard_read && !harvard_write) begin // instruction complete, trigger writeback
+                    clk_internal <= 1'b0;
+                end // otherwise do nothing
+            end
+            2'b10: begin
+                clk_internal <= 1'b0;
+            end
+            2'b11: begin
+                clk_internal <= 1'b0;
+            end
+        endcase
+    end
+    clk_state <= 1'b0;
+end
+
+always @(*) begin
+    case (instr_reg[31:26])
+        6'b101000: begin // Store Byte
+            partial_write = 1'b1;
+            case (harvard_data_address[1:0])
+                2'b00: begin
+                    partial_writedata = {{24{1'b0}}, harvard_writedata[7:0]};
+                    write_byteenable = 4'b0001;
+                    write_data_address = {harvard_data_address[31:2], 2'b00};
+                end
+                2'b01: begin
+                    partial_writedata = {{16{1'b0}}, harvard_writedata[7:0], {8{1'b0}}};
+                    write_byteenable = 4'b0010;
+                    write_data_address = {harvard_data_address[31:2], 2'b00};
+                end
+                2'b10: begin
+                    partial_writedata = {{8{1'b0}}, harvard_writedata[7:0], {16{1'b0}}};
+                    write_byteenable = 4'b0100;
+                    write_data_address = {harvard_data_address[31:2], 2'b00};
+                end
+                2'b11: begin
+                    partial_writedata = {harvard_writedata[7:0], {24{1'b0}}};
+                    write_byteenable = 4'b1000;
+                    write_data_address = {harvard_data_address[31:2], 2'b00};
+                end
+            endcase
+        end
+        6'b101001: begin // Store Halfword
+            partial_write = 1'b1;
+            case (harvard_data_address[1:0])
+                2'b00: begin
+                    partial_writedata = {{16{1'b0}}, harvard_writedata[15:0]};
+                    write_byteenable = 4'b0011;
+                    write_data_address = {harvard_data_address[31:2], 2'b00};
+                end
+                2'b01: begin // halfword address must be matrually aligned, last bit must be 0
+                    partial_writedata = 32'hxxxxxxxx;
+                    write_byteenable = 4'bxxxx;
+                    write_data_address = 32'hxxxxxxxx;
+                end
+                2'b10: begin
+                    partial_writedata = {harvard_writedata[15:0], {16{1'b0}}};
+                    write_byteenable = 4'b1100;
+                    write_data_address = {harvard_data_address[31:2], 2'b00};
+                end
+                2'b11: begin // halfword address must be matrually aligned, last bit must be 0
+                    partial_writedata = 32'hxxxxxxxx;
+                    write_byteenable = 4'bxxxx;
+                    write_data_address = 32'hxxxxxxxx;
+                end
+            endcase
+        end
+        default: begin // Store Word OR All other instructions (These flags are ignored outside the write state)
+            partial_write = 1'b0;
+            partial_writedata = 32'h00000000;
+            write_byteenable = 4'b1111;
+            write_data_address = harvard_data_address;
+        end
+    endcase
+end
+
+always_comb begin
+    if (reset) begin
+        clk_internal = 1'b0;
+        n_state = 2'b00;
+        state = 2'b00;
+        instr_reg = 32'h00000000;
+        address = 32'h00000000;
+        write = 1'b0;
+        read = 1'b0;
+        writedata = 32'h00000000;
+        byteenable = 4'b0000;
+    end else begin
+        case (state)
+            2'b00: begin // connecting wires when in fetch state
+                address = harvard_instr_address;
+                read = 1'b1;
+                write = 1'b0;
+                byteenable = 4'b1111;
+                harvard_readdata = 32'h00000000;
+                writedata = 32'h00000000;
+                n_state = 2'b01;
+            end
+            2'b01: begin // connecting wires when in execute state
+                address = 32'h00000000;
+                read = 1'b0;
+                write = 1'b0;
+                byteenable = 4'b0000;
+                harvard_readdata = 32'h00000000;
+                writedata = 32'h00000000;
+                if (harvard_read) begin
+                    n_state = 2'b10; // next state is read
+                end else if (harvard_write) begin
+                    n_state = 2'b11; // next state is write
+                end else begin
+                    n_state = 2'b00; // next state is fetch
+                end
+            end
+            2'b10: begin // connecting wires when in read state
+                address = harvard_data_address;
+                read = clk_internal ? 1'b1 : 1'b0;
+                write = 1'b0;
+                byteenable = 4'b1111;
+                harvard_readdata = readdata;
+                writedata = 32'h00000000;
+                n_state = 2'b00;
+            end
+            2'b11: begin // connecting wires when in write state
+                address = write_data_address;
+                read = 1'b0;
+                write = 1'b1;
+                byteenable = write_byteenable;
+                harvard_readdata = 32'h00000000;
+                writedata = partial_write ? partial_writedata : harvard_writedata;
+                n_state = 2'b00;
+            end
+        endcase // state
+    end
+end
+
+mips_cpu_harvard mips_cpu_harvard( // Harvard CPU within wrapper
+.clk(clk_internal), // modulated clock input to allow waiting for valid data from memory, input
+.reset(reset), // CPU reset, input
+.active(active), // Is CPU active, output
+.register_v0(register_v0), // $2 / $v0 debug bus, output
+.clk_enable(clk_enable), // unused clock enable, input
+.instr_address(harvard_instr_address), // instr addr from pc, output
+.instr_readdata(instr_reg), // cached instruction passed into harvard cpu, input
+.data_address(harvard_data_address), // harvard data memory address, output
+.data_write(harvard_write), // harvard write flag, output
+.data_read(harvard_read), // harvard read flag, output
+.data_writedata(harvard_writedata), // data output from regfile readport2, output
+.data_readdata(harvard_readdata) // data in from read instruction, input
+);
+
+endmodule

rtl/mips_cpu_control.v

@@ -117,6 +117,8 @@ always @(*) begin
         CtrlMemtoReg = 3'd3;//write data port of regfile is fed from ALUHi
     end else if ((op==SPECIAL)&&(funct == MFLO))begin
         CtrlMemtoReg = 3'd4;//write data port of regfile is fed from ALULo
+    end else if (((op==SPECIAL)&&(funct == JR)) || (op == BEQ) || (op==SW) ||((op==REGIMM)&&(rt==BGEZ)) || (op==BGTZ) || ((op==REGIMM)&&(rt==BLTZ)) || (op==BLEZ) || (op==BNE) || (op==J) || ((op==SPECIAL)&&(funct==MTHI)) || ((op==SPECIAL)&&(funct==MTLO)) || ((op==SPECIAL)&&(funct==MULT)) || ((op==SPECIAL)&&(funct==MULTU)) || ((op==SPECIAL)&&(funct==DIV)) || ((op==SPECIAL)&&(funct==DIVU)) || (op==SB) || (op==SH))begin
+        CtrlMemRead = 0;//Read disabled during jump
     end else begin CtrlMemRead = 1'bx;end//Not all instructions are encompassed so, added incase for debug purposes
 
     //CtrlALUOp Logic

rtl/mips_cpu_npc.v

@@ -9,6 +9,7 @@ reg[31:0] npc_curr;
 
 initial begin
 	npc_curr = (32'hBFC00000 + 32'd4);
+	npc_out = 32'hBFC00000;
 end // initial
 
 always_comb begin

test/test_mips_cpu_bus.sh

@@ -1,4 +1,60 @@
 #!/bin/bash
 
-# should not create any files in the rtl dir
+SRC_DIR=${1?Error: no source directory given in argument};
-# but auxiliary files / dirs can be utilised
+SRC=$(find ./${SRC_DIR}/*);
+SRC_TEMP="";
+for src in ${SRC}
+do
+    SRC_TEMP+=${src}" ";
+done
+SRC=${SRC_TEMP};
+
+
+INSTR=${2:-"No instruction specified: running all testcases"};
+
+if [[ ${INSTR} == "No instruction specified: running all testcases" ]];
+then
+    for DIR in inputs/*/
+    do
+        DIR=$(basename ${DIR});
+        LOOP=$(find inputs/${DIR}/* ! -name '*ref*' ! -name '*log*' ! -name '*data*' ! -name '*out*');
+        for TESTCASE in ${LOOP}
+        do
+            TESTCASE=$([[ ${TESTCASE} =~ /([^./]+)\. ]] && echo "${BASH_REMATCH[1]}");
+            iverilog -Wall -g2012 \
+                -s mips_cpu_bus_tb \
+                -P mips_cpu_bus_tb.INSTR_INIT_FILE=\"inputs/${DIR}/${TESTCASE}.txt\" \
+                -P mips_cpu_bus_tb.DATA_INIT_FILE=\"inputs/${DIR}/${TESTCASE}.data.txt\" \
+                -o exec/mips_cpu_bus_tb_${TESTCASE} testbench/mips_cpu_bus_tb.v testbench/mips_cpu_bus_memory.v \
+                ${SRC} 2> /dev/null
+            ./exec/mips_cpu_bus_tb_${TESTCASE} &> ./inputs/${DIR}/${TESTCASE}.log.txt;             # log file for debugging (contains $display)
+            echo "$(tail -1 ./inputs/${DIR}/${TESTCASE}.log.txt)" > ./inputs/${DIR}/${TESTCASE}.out.txt;      # register v0 output to compare with reference
+            if diff -w ./inputs/${DIR}/${TESTCASE}.out.txt ./inputs/${DIR}/${TESTCASE}.ref.txt &> /dev/null   # compare
+            then 
+                echo ${TESTCASE} ${DIR} "Pass";
+            else 
+                printf '%s %s %s%d %s%d%s\n' "${TESTCASE}" "${DIR}" "Fail Output=" "$(tail -1 ./inputs/${DIR}/${TESTCASE}.out.txt)" "Ref=" "$(tail -1 ./inputs/${DIR}/${TESTCASE}.ref.txt)" 2> /dev/null;
+            fi
+        done
+    done
+else
+    LOOP=$(find inputs/${INSTR}/* ! -name '*ref*' ! -name '*log*' ! -name '*data*' ! -name '*out*');
+    for TESTCASE in ${LOOP}
+    do
+        TESTCASE=$([[ ${TESTCASE} =~ /([^./]+)\. ]] && echo "${BASH_REMATCH[1]}");
+        iverilog -Wall -g2012 \
+        -s mips_cpu_bus_tb \
+        -P mips_cpu_bus_tb.INSTR_INIT_FILE=\"inputs/${INSTR}/${TESTCASE}.txt\" \
+        -P mips_cpu_bus_tb.DATA_INIT_FILE=\"inputs/${INSTR}/${TESTCASE}.data.txt\" \
+        -o exec/mips_cpu_bus_tb_${TESTCASE} testbench/mips_cpu_bus_tb.v testbench/mips_cpu_bus_memory.v \
+        ${SRC} 2> /dev/null
+        ./exec/mips_cpu_bus_tb_${TESTCASE} &> ./inputs/${INSTR}/${TESTCASE}.log.txt;             # log file for debugging (contains $display)
+        echo "$(tail -1 ./inputs/${INSTR}/${TESTCASE}.log.txt)" > ./inputs/${INSTR}/${TESTCASE}.out.txt;      # register v0 output to compare with reference
+        if diff -w ./inputs/${INSTR}/${TESTCASE}.out.txt ./inputs/${INSTR}/${TESTCASE}.ref.txt &> /dev/null   # compare
+        then 
+            echo ${TESTCASE} ${INSTR} "Pass";
+        else 
+            printf '%s %s %s%d %s%d%s\n' "${TESTCASE}" "${INSTR}" "Fail Output=" "$(tail -1 ./inputs/${INSTR}/${TESTCASE}.out.txt)" "Ref=" "$(tail -1 ./inputs/${INSTR}/${TESTCASE}.ref.txt)" 2> /dev/null;
+        fi
+    done
+fi

test/test_mips_cpu_harvard.sh

@@ -47,7 +47,7 @@ else
         -P mips_cpu_harvard_tb.INSTR_INIT_FILE=\"inputs/${INSTR}/${TESTCASE}.txt\" \
         -P mips_cpu_harvard_tb.DATA_INIT_FILE=\"inputs/${INSTR}/${TESTCASE}.data.txt\" \
         -o exec/mips_cpu_harvard_tb_${TESTCASE} testbench/mips_cpu_harvard_tb.v testbench/mips_cpu_memory.v\
-        ${SRC} #2> /dev/null
+        ${SRC} 2> /dev/null
         ./exec/mips_cpu_harvard_tb_${TESTCASE} &> ./inputs/${INSTR}/${TESTCASE}.log.txt;             # log file for debugging (contains $display)
         echo "$(tail -1 ./inputs/${INSTR}/${TESTCASE}.log.txt)" > ./inputs/${INSTR}/${TESTCASE}.out.txt;      # register v0 output to compare with reference
         if diff -w ./inputs/${INSTR}/${TESTCASE}.out.txt ./inputs/${INSTR}/${TESTCASE}.ref.txt &> /dev/null   # compare

testbench/mips_cpu_bus_memory.v

@@ -0,0 +1,100 @@
+module mips_cpu_bus_memory( //Avalon memory mapped bus controller (slave)
+    input logic clk,
+    input logic reset,
+    input logic[31:0] address,
+    input logic write,
+    input logic read,
+    output logic waitrequest,
+    input logic[31:0] writedata,
+    input logic[3:0] byteenable,
+    output logic[31:0] readdata
+);
+
+parameter INSTR_INIT_FILE = "";
+parameter DATA_INIT_FILE = "";
+
+logic [31:0] data_memory [0:63]; // location 0x00001000 onwards
+logic [31:0] instr_memory [0:63]; // location 0xBFC00000 onwards
+
+initial begin
+    for (integer i=0; i<$size(data_memory); i++) begin //Initialise data to zero by default
+        data_memory[i] = 0;
+    end
+
+    for (integer i=0; i<$size(instr_memory); i++) begin //Initialise instr to zero by default
+        instr_memory[i] = 0;
+    end
+
+    if (INSTR_INIT_FILE != "") begin //Load instr contents from file if specified
+        $display("RAM: Loading RAM contents from %s", INSTR_INIT_FILE);
+        $readmemh(INSTR_INIT_FILE, instr_memory);
+    end
+
+    for (integer i = 0; i<$size(instr_memory); i++) begin //Read out instr contents to log
+        $display("byte +%h: %h", 32'hBFC00000+i*4, instr_memory[i]);
+    end
+
+    if (DATA_INIT_FILE != "") begin //Load data contents from file if specified
+        $display("MEM: Loading MEM contents from %s", DATA_INIT_FILE);
+        $readmemh(DATA_INIT_FILE, data_memory);
+    end else begin
+        $display("MEM FILE NOT GIVEN");
+    end
+
+    for (integer i = 0; i<$size(data_memory); i++) begin //Read out data contents to log
+        $display("byte +%h: %h", 32'h00001000+i*4, data_memory[i]);
+    end
+
+    waitrequest = 1'b0; // set waitrequest low to begin
+    readdata = 32'h00000000; // set readdata low to begin
+
+end
+
+always_comb begin
+    if (reset) begin
+        waitrequest = 1'b0;
+    end
+end
+
+always_ff @(posedge read or posedge write) begin
+    waitrequest <= 1'b1;
+end
+
+always_ff @(posedge clk) begin
+    if (waitrequest) begin
+        if (read) begin
+            if (address >= 32'hBFC00000) begin // instruction read
+                readdata <= instr_memory[{address-32'hBFC00000}>>2];
+            end else if (address >= 32'h00001000) begin // data read
+                readdata <= data_memory[{address-32'h00001000}>>2];
+            end
+            waitrequest <= 1'b0; // end with setting waitrequest low
+        end else if (write) begin
+            if (address >= 32'hBFC00000) begin // writing to instr mem area is invalid
+                $display("Error, write attempted in instr area at address: %h", address);
+            end else if (address >= 32'h00001000) begin // write to data mem
+                if (byteenable[3]) begin // if first byte enabled, write
+                    data_memory[{address-32'h00001000}>>2][31:24] <= writedata[31:24];
+                end
+                if (byteenable[2]) begin // if second byte enabled, write
+                    data_memory[{address-32'h00001000}>>2][23:16] <= writedata[23:16];
+                end
+                if (byteenable[1]) begin // if third byte enabled, write
+                    data_memory[{address-32'h00001000}>>2][15:8] <= writedata[15:8];
+                end
+                if (byteenable[0]) begin // if fourth byte enabled, write
+                    data_memory[{address-32'h00001000}>>2][7:0] <= writedata[7:0];
+                end
+                waitrequest <= 1'b0; // end with setting waitrequest low
+            end
+        end else begin
+            waitrequest <= 1'bx;
+            readdata <= 32'hxxxxxxxx;
+        end
+    end else begin
+        waitrequest <= 1'b0;
+        readdata <= 32'h00000000;
+    end
+end
+
+endmodule

testbench/mips_cpu_bus_tb.v

@@ -1,26 +1,43 @@
 module mips_cpu_bus_tb;
-    timeunit 1ns / 10ps;
 
-    parameter RAM_INIT_FILE = "test/01-binary/countdown.hex.txt";
+parameter INSTR_INIT_FILE = "";
-    parameter TIMEOUT_CYCLES = 10000;
+parameter DATA_INIT_FILE = "";
+parameter TIMEOUT_CYCLES = 100; // Timeout cycles are higher to account for memory stall delays
 
-    logic clk;
+logic clk, reset, active, write, read, waitrequest;
-    logic rst;
+logic[31:0] address, register_v0, writedata, readdata;
+logic[3:0] byteenable;
 
-    logic running;
+mips_cpu_bus_memory #(INSTR_INIT_FILE, DATA_INIT_FILE) memInst( //Avalon memory mapped bus controller (slave)
+    .clk(clk), // clk input to mem
+    .reset(reset), // reset input to stall mem during cpu reset
+    .address(address), // addr input to mem
+    .write(write), // write flag input
+    .read(read), // read flag input
+    .waitrequest(waitrequest), // mem stall output
+    .writedata(writedata), // data to be written
+    .byteenable(byteenable), // byteenable bus for writes
+    .readdata(readdata) // read output port
+);
 
-    logic[11:0] address;
+mips_cpu_bus cpuInst(
-    logic write;
+    .clk(clk), // clk input to cpu wrapper
-    logic read;
+    .reset(reset), // reset input
-    logic[15:0] writedata;
+    .active(active), // active output flag
-    logic[15:0] readdata;
+    .register_v0(register_v0), // debug $2 or $v0 output bus
+    .address(address), // mem addr output
+    .write(write), // mem write output flag
+    .read(read), // mem read output flag
+    .waitrequest(waitrequest), // mem stall input flag
+    .writedata(writedata), // data to write to mem output
+    .byteenable(byteenable), // bytes to write output
+    .readdata(readdata) // data from mem input
+);
 
-    RAM_16x4096_delay1 #(RAM_INIT_FILE) ramInst(clk, address, write, read, writedata, readdata);
+// Setup and clock
-    
-    CPU_MU0_delay1 cpuInst(clk, rst, running, address, write, read, writedata, readdata);
-
-    // Generate clock
 initial begin
+    $dumpfile("mips_cpu_bus.vcd");
+    $dumpvars(0,mips_cpu_bus_tb);
     clk=0;
 
     repeat (TIMEOUT_CYCLES) begin
@@ -34,28 +51,30 @@ module mips_cpu_bus_tb;
 end
 
 initial begin    
-        rst <= 0;
+    reset <= 1;
+    @(posedge clk);
+    reset <= 0;
 
     @(posedge clk);
-        rst <= 1;
+    assert(active==1)
+    else $display("TB : CPU did not set active=1 after reset.");
 
+    while (active) begin
+        //$display("Clk: %d", clk);
         @(posedge clk);
-        rst <= 0;
+        //$display("Register v0: %d", register_v0);
-
+        //$display("Reg File Write data: %d", cpuInst.in_writedata);
-        @(posedge clk);
+        $display("Reg File Out Read data: %h", cpuInst.mips_cpu_harvard.out_readdata1);
-        assert(running==1)
+        $display("Reg File opcode: %b", cpuInst.mips_cpu_harvard.regfile.opcode);
-        else $display("TB : CPU did not set running=1 after reset.");
+        //$display("ALU output: %h", cpuInst.out_ALURes);
-
+        //$display("ALU input B: %h", cpuInst.alu.B);
-        while (running) begin
-            @(posedge clk);
     end
 
-        $display("TB : finished; running=0");
+    @(posedge clk);
-
+    $display("TB: CPU Halt; active=0");
+    $display("Output:");
+    $display("%d",register_v0);
     $finish;
-        
 end
 
-    
-
 endmodule