在verilog中进行计数器，Modelsim

Question

i'm trying to make round robin counter in verilog

module rr_arbiter (
clk, // positive edge trigger
reset,  // negative edge trigger
req0, req1, req2, req3, 
grant0, grant1, grant2, grant3,
priority, priority_req);

input clk, reset;
input req0, req1, req2, req3;
input priority;
input [1:0] priority_req;

output grant0, grant1, grant2, grant3;  

reg x 

always(posedge clk or negedge reset) begin
pirority_req = priority;

if (reset) begin
    grant0 <= 1'b0;
    grant1 <= 1'b0;
    grant2 <= 1'b0;
    grant3 <= 1'b0;
   end
else
begin
    if(priority == 1)
        if (priority req == 2b'00)
            begin
            x=1;
            grant0 <= (grant0*(~x))+(grant1*x);     
            x=0;
            grant0 <= (grant0*(~x))+(grant1*x);
            grant1 <= grant2;
            grant2 <= grant3;
            grant3 <= grant1;
            //  counter 0012300123
            end
        else if (priority req == 2b'01)
            begin
            grant0 <= grant1;
            x=1;
            grant1 <= (grant1*(~x))+(grant2*x);
            x=0;
            grant1 <= (grant1*(~x))+(grant2*x);
            grant2 <= grant3;
            grant3 <= grant1;
            //  counter 0112301123
            end
        else if (priority req == 2b'10)
            begin
            grant0 <= grant1;
            grant1 <= grant2;
            x=1;
            grant2 <= (grant2*(~x))+(grant3*x);
            x=0;
            grant2 <= (grant2*(~x))+(grant3*x);
            grant3 <= grant1;
            //  counter 0122301223
            end
        else if (priority req == 2b'11)
            begin
            grant0 <= grant1;
            grant1 <= grant2;
            grant2 <= grant3;
            x=1;
            grant3 <= (grant3*(~x))+(grant1*x);
            x=0;
            grant3 <= (grant3*(~x))+(grant1*x);
            //  counter 0123301233
            end
    end

    else 
    begin
        grant0 <= ~grant2 * grant3;
        grant1 <= grant0;
        grant2 <= grant1;
        grant3 <= grant2;
        //counter 01230123
    end
end
end

end

endmodule 

as you can see, i'm trying to make round robin counter. each case it's like (grant)01230123.., 0012300123.., 0112301123.., 0122301223.., 0123301233...

** Error: (vlog-13069) C:/Modeltech_pe_edu_10.4a/examples/rr_arbiter.v(17): near "always": syntax error, unexpected always, expecting ';' or ','.

** Error: (vlog-13069) C:/Modeltech_pe_edu_10.4a/examples/rr_arbiter.v(22): near "<=": syntax error, unexpected <=.

** Error: C:/Modeltech_pe_edu_10.4a/examples/rr_arbiter.v(22): (vlog-13205) Syntax error found in the scope following 'grant0'. Is there a missing '::'?

Answer 1

The error message for line 17 is self-explanatory. It is expecting a ';'. You are missing a ';' on line 15.

If an error message appears to make no sense, always cast your eye up the screen to see whether the problem is with a previous line.