altos/lisp: re-use small frames

This saves a pile more use of the allocator by noting when frames have
not been referenced from another frame and freeing them when they go
out of scope. Frames with references are left to the allocator to deal
with.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 35 insertions, 2 deletions

diff --git a/src/lisp/ao_lisp.h b/src/lisp/ao_lisp.h
index 2db4914f..bcb0a17f 100644
--- a/src/lisp/ao_lisp.h
+++ b/src/lisp/ao_lisp.h
@@ -156,13 +156,33 @@ struct ao_lisp_val {
 
 struct ao_lisp_frame {
 	uint8_t			type;
-	uint8_t			num;
-	ao_poly			next;
+	uint8_t			_num;
+	ao_poly			prev;
 	struct ao_lisp_val	vals[];
 };
 
+#define AO_LISP_FRAME_NUM_MASK	0x7f
+
+/* Set when the frame escapes the lambda */
+#define AO_LISP_FRAME_MARK	0x80
+
+static inline int ao_lisp_frame_num(struct ao_lisp_frame *f) {
+	if (f->_num == 0xff)
+		ao_lisp_abort();
+	return f->_num & AO_LISP_FRAME_NUM_MASK;
+}
+
+static inline int ao_lisp_frame_marked(struct ao_lisp_frame *f) {
+	if (f->_num == 0xff)
+		ao_lisp_abort();
+	return f->_num & AO_LISP_FRAME_MARK;
+}
+
 static inline struct ao_lisp_frame *
 ao_lisp_poly_frame(ao_poly poly) {
+	struct ao_lisp_frame *frame = ao_lisp_ref(poly);
+	if (frame && frame->_num == 0xff)
+		ao_lisp_abort();
 	return ao_lisp_ref(poly);
 }
 
@@ -500,6 +520,9 @@ ao_lisp_atom_print(ao_poly a);
 struct ao_lisp_atom *
 ao_lisp_atom_intern(char *name);
 
+ao_poly *
+ao_lisp_atom_ref(struct ao_lisp_frame *frame, ao_poly atom);
+
 ao_poly
 ao_lisp_atom_get(ao_poly atom);
 
@@ -574,12 +597,22 @@ ao_lisp_read_eval_print(void);
 /* frame */
 extern const struct ao_lisp_type ao_lisp_frame_type;
 
+#define AO_LISP_FRAME_FREE	4
+
+extern struct ao_lisp_frame	*ao_lisp_frame_free_list[AO_LISP_FRAME_FREE];
+
+ao_poly
+ao_lisp_frame_mark(struct ao_lisp_frame *frame);
+
 ao_poly *
 ao_lisp_frame_ref(struct ao_lisp_frame *frame, ao_poly atom);
 
 struct ao_lisp_frame *
 ao_lisp_frame_new(int num);
 
+void
+ao_lisp_frame_free(struct ao_lisp_frame *frame);
+
 int
 ao_lisp_frame_add(struct ao_lisp_frame **frame, ao_poly atom, ao_poly val);