module
    isSigNaNRecFN#(parameter expWidth = 3, parameter sigWidth = 3) (
        input [(expWidth + sigWidth):0] in, output isSigNaN
    );

    wire isNaN =
        (in[(expWidth + sigWidth - 1):(expWidth + sigWidth - 3)] == 'b111);
    assign isSigNaN = isNaN && !in[sigWidth - 2];

endmodule