(define %bignum-quotient
  (letrec
    ((bqn (lambda (u v nu nv)
	    (if (bignum? nv)
		(bqn u v (quotient nu 2) (quotient nv 2))
		(begin
;		  (writeln "norm" nu nv)
		  (bqd u v nu nv)))))
     (bqd (lambda (u v nu nv)
	    (let* ((tq (quotient nu nv))
		   (tr (- u (* tq v))))
;	      (writeln "tq" tq "tr" tr)
	      (if (or (negative? tr) (>= tr v))
		  (begin
;		    (writeln "tq needs adj.")
		    (let* ((atr (abs tr))
			   (a (bqn atr v atr v)))
;		      (writeln a)
		      (let* ((tq (if (negative? tr)
				     (- tq (add1 (car a)))
				     (+ tq (car a))))
			     (tr (- u (* tq v))))
;			(writeln "atq" tq "atr" tr)
			(if (or (negative? tr) (>= tr v))
			    (begin
;			      (writeln "tq needs further adjustment")
			      (let* ((tq (if (negative? tr)
					     (sub1 tq)
					     (add1 tq)))
				     (tr (- u (* tq v))))
;				(writeln "fatq" tq "fatr" tr)
				(if (or (negative? tr) (>= tr v))
				    (error '%bignum-quotient "internal error")
				    (cons tq tr))))
			    (cons tq tr)))))
		  (cons tq tr))))))
    (lambda (u v w)
;     (writeln "init" u v)
      (let* ((au (abs u))
	     (av (abs v))
	     (su (negative? u))
	     (sv (negative? v))
	     (result (bqn au av au av))
	     (q (car result))
	     (r (cdr result)))
	(if w
	    (if (eq? su sv) q (- q))
	    (if su (- r) r))))))