1.1 --- a/ula.py	Sun Dec 18 18:56:39 2011 +0100
     1.2 +++ b/ula.py	Sun Dec 18 18:59:08 2011 +0100
     1.3 @@ -13,26 +13,33 @@
     1.4  MAX_MEMORY = 0x10000    # the number of addressable memory locations
     1.5  BLANK = (0, 0, 0)
     1.6  
     1.7 -def update(screen, ula):
     1.8 +def update(ula):
     1.9  
    1.10      """
    1.11 -    Update the 'screen' array by reading from the 'ula'. This function
    1.12 -    effectively has the role of the video circuit, but also provides the clock
    1.13 -    signal to the ULA.
    1.14 +    Return a screen array by reading from the 'ula'. This function effectively
    1.15 +    has the role of the video circuit, but also provides the clock signal to the
    1.16 +    ULA.
    1.17      """
    1.18  
    1.19 +    screen = []
    1.20 +
    1.21      ula.vsync()
    1.22      y = 0
    1.23      while y < MAX_SCANLINE:
    1.24 +        row = []
    1.25          x = 0
    1.26          while x < MAX_SCANPOS:
    1.27              colour = ula.get_pixel_colour()
    1.28              if x < MAX_WIDTH and y < MAX_HEIGHT:
    1.29 -                screen[x][y] = colour
    1.30 +                row.append(colour)
    1.31              x += 1
    1.32          ula.hsync()
    1.33 +        if y < MAX_HEIGHT:
    1.34 +            screen.append(row)
    1.35          y += 1
    1.36  
    1.37 +    return screen
    1.38 +
    1.39  class ULA:
    1.40  
    1.41      "The ULA functionality."
    1.42 @@ -276,17 +283,6 @@
    1.43  
    1.44      return [0] * MAX_MEMORY
    1.45  
    1.46 -def get_screen():
    1.47 -
    1.48 -    "Return a list of arrays representing the display."
    1.49 -
    1.50 -    x = 0
    1.51 -    screen = []
    1.52 -    while x < MAX_WIDTH:
    1.53 -        screen.append([(0, 0, 0)] * MAX_HEIGHT)
    1.54 -        x += 1
    1.55 -    return screen
    1.56 -
    1.57  def fill(memory, start, end, value):
    1.58      i = start
    1.59      while i < end:
    1.60 @@ -303,7 +299,6 @@
    1.61      # Make a simple two-dimensional array of tuples (three-dimensional in pygame
    1.62      # terminology).
    1.63  
    1.64 -    a = get_screen()
    1.65 -    update(a, ula)
    1.66 +    a = update(ula)
    1.67  
    1.68  # vim: tabstop=4 expandtab shiftwidth=4