altos/lisp: Cache freed cons and stack items

[fw/altos] / src / lisp / ao_lisp_cons.c

diff --git a/src/lisp/ao_lisp_cons.c b/src/lisp/ao_lisp_cons.c
index 311d63ab8dc3dd0497f1edb3385d219eeda42e14..d2b60c9a6561b06f1ec926d864d0c9934de951af 100644 (file)
--- a/src/lisp/ao_lisp_cons.c
+++ b/src/lisp/ao_lisp_cons.c
@@ -69,23 +69,41 @@ const struct ao_lisp_type ao_lisp_cons_type = {
        .name = "cons",
 };
 
+struct ao_lisp_cons *ao_lisp_cons_free_list;
+
 struct ao_lisp_cons *
 ao_lisp_cons_cons(ao_poly car, struct ao_lisp_cons *cdr)
 {
        struct ao_lisp_cons     *cons;
 
-       ao_lisp_poly_stash(0, car);
-       ao_lisp_cons_stash(0, cdr);
-       cons = ao_lisp_alloc(sizeof (struct ao_lisp_cons));
-       car = ao_lisp_poly_fetch(0);
-       cdr = ao_lisp_cons_fetch(0);
-       if (!cons)
-               return NULL;
+       if (ao_lisp_cons_free_list) {
+               cons = ao_lisp_cons_free_list;
+               ao_lisp_cons_free_list = ao_lisp_poly_cons(cons->cdr);
+       } else {
+               ao_lisp_poly_stash(0, car);
+               ao_lisp_cons_stash(0, cdr);
+               cons = ao_lisp_alloc(sizeof (struct ao_lisp_cons));
+               car = ao_lisp_poly_fetch(0);
+               cdr = ao_lisp_cons_fetch(0);
+               if (!cons)
+                       return NULL;
+       }
        cons->car = car;
        cons->cdr = ao_lisp_cons_poly(cdr);
        return cons;
 }
 
+void
+ao_lisp_cons_free(struct ao_lisp_cons *cons)
+{
+       while (cons) {
+               ao_poly cdr = cons->cdr;
+               cons->cdr = ao_lisp_cons_poly(ao_lisp_cons_free_list);
+               ao_lisp_cons_free_list = cons;
+               cons = ao_lisp_poly_cons(cdr);
+       }
+}
+
 void
 ao_lisp_cons_print(ao_poly c)
 {