altos/lisp: Sort frames by atom

Fortunately, the collector always retains the relative order between
addresses, so we can sort based on the atom address itself. This
reduces the time spent looking for names in larger (e.g. global)
frames.

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

1 files changed, 40 insertions, 11 deletions

diff --git a/src/lisp/ao_lisp_frame.c b/src/lisp/ao_lisp_frame.c
index 17fa141a..05f6d253 100644
--- a/src/lisp/ao_lisp_frame.c
+++ b/src/lisp/ao_lisp_frame.c
@@ -128,14 +128,32 @@ ao_lisp_frame_print(ao_poly p)
 	printf("}");
 }
 
+static int
+ao_lisp_frame_find(struct ao_lisp_frame *frame, int top, ao_poly atom)
+{
+	int l = 0;
+	int r = top - 1;
+	while (l <= r) {
+		int m = (l + r) >> 1;
+		if (frame->vals[m].atom < atom)
+			l = m + 1;
+		else
+			r = m - 1;
+	}
+	return l;
+}
+
 ao_poly *
 ao_lisp_frame_ref(struct ao_lisp_frame *frame, ao_poly atom)
 {
-	int f;
-	for (f = 0; f < frame->num; f++)
-		if (frame->vals[f].atom == atom)
-			return &frame->vals[f].val;
-	return NULL;
+	int l = ao_lisp_frame_find(frame, frame->num, atom);
+
+	if (l >= frame->num)
+		return NULL;
+
+	if (frame->vals[l].atom != atom)
+		return NULL;
+	return &frame->vals[l].val;
 }
 
 int
@@ -234,6 +252,18 @@ ao_lisp_frame_realloc(struct ao_lisp_frame **frame_ref, int new_num)
 	return new;
 }
 
+void
+ao_lisp_frame_bind(struct ao_lisp_frame *frame, int num, ao_poly atom, ao_poly val)
+{
+	int l = ao_lisp_frame_find(frame, num, atom);
+
+	memmove(&frame->vals[l+1],
+		&frame->vals[l],
+		(num - l) * sizeof (struct ao_lisp_val));
+	frame->vals[l].atom = atom;
+	frame->vals[l].val = val;
+}
+
 int
 ao_lisp_frame_add(struct ao_lisp_frame **frame_ref, ao_poly atom, ao_poly val)
 {
@@ -251,14 +281,13 @@ ao_lisp_frame_add(struct ao_lisp_frame **frame_ref, ao_poly atom, ao_poly val)
 			f = 0;
 			frame = ao_lisp_frame_new(1);
 		}
-		atom = ao_lisp_poly_fetch(0);
-		val = ao_lisp_poly_fetch(1);
 		if (!frame)
 			return 0;
 		*frame_ref = frame;
-		frame->vals[f].atom = atom;
-		ref = &frame->vals[f].val;
-	}
-	*ref = val;
+		atom = ao_lisp_poly_fetch(0);
+		val = ao_lisp_poly_fetch(1);
+		ao_lisp_frame_bind(frame, frame->num - 1, atom, val);
+	} else
+		*ref = val;
 	return 1;
 }