makeatletter

% Magnitude Comparator (magn comparator) shape
pgfdeclareshape{magn comparator}
{
    % The 'minimum width' and 'minimum height' keys, not the content, determine
    % the size
    savedanchornortheast
    {%
        pgfmathsetlengthpgf@x{pgfshapeminwidth}%
        pgfmathsetlengthpgf@y{pgfshapeminheight}%
        pgf@x=0.5pgf@x
        pgf@y=0.5pgf@y
    }
    % This is redundant, but makes some things easier:
    savedanchorsouthwest
    {%
        pgfmathsetlengthpgf@x{pgfshapeminwidth}%
        pgfmathsetlengthpgf@y{pgfshapeminheight}%
        pgf@x=-0.5pgf@x
        pgf@y=-0.5pgf@y
    }
    % Inherit from rectangle
    inheritanchorborder[from=rectangle]

    % Define same anchor a normal rectangle has
    anchor{center}{pgfpointorigin}
    anchor{north}{northeast pgf@x=0pt}
    anchor{east}{northeast pgf@y=0pt}
    anchor{south}{southwest pgf@x=0pt}
    anchor{west}{southwest pgf@y=0pt}
    anchor{north east}{northeast}
    anchor{north west}{northeast pgf@x=-pgf@x}
    anchor{south west}{southwest}
    anchor{south east}{southwest pgf@x=-pgf@x}
    anchor{text}
    {
        pgfpointorigin
        advancepgf@x by -.5wdpgfnodeparttextbox%
        advancepgf@y by -.5htpgfnodeparttextbox%
        advancepgf@y by +.5dppgfnodeparttextbox%
    }

    % Define anchors for input signal ports
    anchor{input gt}
    {
        pgf@process{southwest}%
        pgf@y=-.5pgf@y%
    }
    anchor{input eq}
    {
        pgf@process{southwest}%
        pgf@y=0pt%
    }
    anchor{input lt}
    {
        pgf@process{southwest}%
        pgf@y=.5pgf@y%
    }
    anchor{input a}
    {
        pgf@process{northeast}%
        pgf@x=-.3pgf@x%
    }
    anchor{input b}
    {
        pgf@process{northeast}%
        pgf@x=.3pgf@x%
    }

    % Define anchors for output signal ports
    anchor{output gt}
    {
        pgf@process{northeast}%
        pgf@y=.5pgf@y%
    }
    anchor{output eq}
    {
        pgf@process{northeast}%
        pgf@y=0pt%
    }
    anchor{output lt}
    {
        pgf@process{northeast}%
        pgf@y=-.5pgf@y%
    }

    % Draw the rectangle box and the port labels
    backgroundpath
    {
        % Rectangle box
        pgfpathrectanglecorners{southwest}{northeast}
        % node [and gate] (kek) at (0, 0) {};
    }
}

% Define default style for this node
tikzset
{
    every magn comparator node/.style =
    {
        draw,
        minimum width = 2cm,
        minimum height = 2cm,
        thick,
        inner sep = 1mm,
        outer sep = 0pt,
        cap = round
    }
}

makeatother