cleaning; optimize screen_bounce.csn

examples/screen_bounce.csn

@@ -4,21 +4,20 @@
     (sc-opt 1 1) ; auto blit
     (sc-opt 2 25) ; frame rate
 
-    (ld r0 5) ; x
-    (ld r1 0) ; y
+    (sym x r0) (sym y r1) (sym dx r2) (sym dy r3) (sym color r5)
 
-    (ld r2 1) ; dx
-    (ld r3 1) ; dy
-
-    (ld r5 0x3300ff)
+    (ld x 5) (ld y 0)
+    (ld dx 1) (ld dy 1)
+    (ld color 0x3300ff)
 
     (:loop)
-        (add r5 0x000001)
-        (sc-px r0 r1 r5)
-        (add r0 r2)
-        (add r1 r3)
-        (cmp r0 799 (eq? (ld r2 -1)) (ne? (cmp r0 0 (eq? (ld r2 1)))))
-        (cmp r1 599 (eq? (ld r3 -1)) (ne? (cmp r1 0 (eq? (ld r3 1)))))
+        (add color 0x000001)
+        (sc-px x y color)
+
+        (add x dx (z? (ld dx 1)))
+        (cmp x 799 (eq? (ld dx -1)))
+
+        (add y dy (z? (ld dy 1)))
+        (cmp y 599 (eq? (ld dy -1)))
     (j :loop)
-    (fault "unreachable")
 )