1 # Draw pixels in response to keyboard events, starting from the top-left
 2 # and in raster order.
 3 #
 4 # To build a disk image:
 5 #   ./translate apps/ex3.mu        # emits code.img
 6 # To run:
 7 #   qemu-system-i386 code.img
 8 #
 9 # Expected output: a new green pixel starting from the top left corner of the
10 # screen every time you press a key (letter or digit)
11 
12 fn main screen: (addr screen), keyboard: (addr keyboard), data-disk: (addr disk) {
13   var x/ecx: int <- copy 0
14   var y/edx: int <- copy 0
15   {
16     var key/eax: byte <- read-key keyboard
17     compare key, 0
18     loop-if-=  # busy wait
19     pixel-on-real-screen x, y, 0x31/green
20     x <- increment
21     compare x, 0x400/screen-width=1024
22     {
23       break-if-<
24       y <- increment
25       x <- copy 0
26     }
27     loop
28   }
29 }