gEDA: $signed in iverilog

[Yasuhisa Kato]

Hi Steve,

ivl-bugs seems not to be available right now. So I resend this mail to geda-dev.

Sign extension does not work well with $signed in 20030613 snapshot. An attached file 
is a testcase.

Thanks,
- Kato

module  main;

    reg     [11:0]  sum;
    wire    [10:0]  a = 11'b111_0000_0000;
    wire    [10:0]  b = 11'b000_0000_1111;
    
    initial begin
        #1 sum  = $signed(a) + $signed(b);
        
        if (sum == 12'b1111_0000_1111)
            $display("PASSED");
        else
            $display("failed: %b",sum);

        $finish;
    end
    
endmodule