Endless shitposting cube

endless.lisp

    (defun endless (str pos len)
      (if (<= pos len)
          (elt str pos)
          (if (zerop (mod pos len))
              (elt str len)
              (elt str (1- (mod pos len))))))

    (defun square-val (x y str len)
      (cond
        ((eql y 0) (elt str x))
        ((eql x 0) (elt str y))
        ((and (eql x len) (eql y len)) (elt str 0))
        ((eql y len) (elt str (- len x)))
        ((eql x len) (elt str (- len y)))
        (t (endless str (+ x y) len))))

    (defun print-square (str)
      (let ((len (1- (length str))))
        (loop for y from 0 to len do
              (format t "      ") ;indent
              (loop for x from 0 to len 
                    for chr = (square-val x y str len)
                    do (format t "~C " chr))
              (terpri))))