module pl_hazard_unit (input branchd, mtorfsele, mtorfselm, rfwee, rfwem, rfwew, jumpd,
                       input [4:0] rsd, rtd, rse, rte, rfae, rfam, rfaw,
                       output stall,
                       output reg flush,
                       output reg forwardad, forwardbd,
                       output reg [1:0] forwardae, forwardbe);
reg lwstall, bstall;
always @(*) begin
    forwardad <= 0;
    forwardbd <= 0;
    forwardae <= 0;
    forwardbe <= 0;

    //execute operand 1
    if ((rse != 0) && (rse == rfam) && rfwem) forwardae <= 2'b10;
    else if ((rse != 0) && (rfwew) && (rse == rfaw)) forwardae <= 2'b01;
    else forwardae <= 2'b00;

    //execute operand 2
    if ((rte != 0) && (rse == rfam) && rfwem) forwardbe <= 2'b10;
    else if ((rte != 0) && (rfwew) && (rse == rfaw)) forwardbe <= 2'b01;
    else forwardbe <= 2'b00;

    //ID (branch) operand 1
    if ((rsd != 0) && (rsd == rfam) && (rfwem)) forwardad <= 1'b1;
    else forwardad <= 1'b0;

    //ID (branch) operand 2
    if ((rtd!= 0) && (rtd == rfam) && (rfwem)) forwardbd <= 1'b1;
    else forwardbd <= 1'b0;

    //lw stall (if LW is EX and dependent is in ID, stall 1 and flush the stage between)
    if ((mtorfsele && ((rte == rsd) || (rte == rtd)))) begin
        lwstall <= 1'b1;
        flush <= 1'b1;
    end
    else begin
        lwstall <= 1'b0;
        flush <= 1'b0;
    end

    //branch stall (if branch instr (in ID) is dependent on instr in EX, or LW in MEM, stall 1)
    if (((rsd == rfae) || (rtd == rfae)) && (branchd) && (rfwee) || ((rsd == rfam) || (rtd == rfam)) && (branchd) && (mtorfselm))
        bstall <= 1'b1;
    else bstall <= 1'b0;
end
assign stall = lwstall | bstall;

endmodule