# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1324232351 -3600
# Node ID e157bb40cc8cfa278bd099b6a1e9dd2395540a74
# Parent  b6680c1bb8b77695a18022c74a1215f2d5ae817f
Replaced the use of nested lists with a flat, genuine, global screen array.
Introduced conversion of the screen array to a list in order to work with Shedskin.

diff -r b6680c1bb8b7 -r e157bb40cc8c main.py
--- a/main.py	Sun Dec 18 18:59:08 2011 +0100
+++ b/main.py	Sun Dec 18 19:19:11 2011 +0100
@@ -25,7 +25,7 @@
     # Copy the array to a surface and apply a pixel intensity.
 
     try:
-        a[:] = screen_array
+        a.flat[:] = screen_array
         a *= INTENSITY
     finally:
         del a, sa
diff -r b6680c1bb8b7 -r e157bb40cc8c ula.py
--- a/ula.py	Sun Dec 18 18:59:08 2011 +0100
+++ b/ula.py	Sun Dec 18 19:19:11 2011 +0100
@@ -4,6 +4,9 @@
 Acorn Electron ULA simulation.
 """
 
+from array import array
+from itertools import repeat
+
 LINES_PER_ROW = 8       # the number of pixel lines per character row
 MAX_HEIGHT = 256        # the height of the screen in pixels
 MAX_SCANLINE = 312      # the number of scanlines in each frame
@@ -13,6 +16,8 @@
 MAX_MEMORY = 0x10000    # the number of addressable memory locations
 BLANK = (0, 0, 0)
 
+screen = array("B", repeat(0, MAX_WIDTH * 3 * MAX_HEIGHT))
+
 def update(ula):
 
     """
@@ -21,24 +26,22 @@
     ULA.
     """
 
-    screen = []
-
     ula.vsync()
+    pos = 0
     y = 0
     while y < MAX_SCANLINE:
-        row = []
         x = 0
         while x < MAX_SCANPOS:
             colour = ula.get_pixel_colour()
             if x < MAX_WIDTH and y < MAX_HEIGHT:
-                row.append(colour)
+                screen[pos] = colour[0]; pos += 1
+                screen[pos] = colour[1]; pos += 1
+                screen[pos] = colour[2]; pos += 1
             x += 1
         ula.hsync()
-        if y < MAX_HEIGHT:
-            screen.append(row)
         y += 1
 
-    return screen
+    return screen.tolist()
 
 class ULA: