preliminary cont work

src/prolog/lib/cont.pl

@@ -0,0 +1,29 @@
+
+:- module(cont, [reset/3, shift/1]).
+
+reset(Goal, Cont, Term) :-
+    call(Goal),
+    '$reset_cont_marker',
+    '$bind_from_register'(Cont, 3),
+    '$bind_from_register'(Term, 4).
+
+shift(Term) :-
+    '$nextEP'(first, E, P),
+    get_chunks(E, P, L),
+    Cont = cont(call_continuation(L)),
+    '$write_cont_and_term'(_, _, Cont, Term),
+    '$unwind_environments'.
+
+get_chunks(E, P, L) :-
+    (  '$points_to_cont_reset_marker'(P) ->
+       L = []
+    ;  '$get_chunk'(E,P,TB),
+       L = [TB|Rest],
+       '$nextEP'(E, NextE, NextP),
+       get_chunks(NextE, NextP, Rest)
+    ).
+
+call_continuation(L) :- '$call_continuation'(L).
+
+'$write_cont_and_term'(_, _, _, _).
+