https://github.com/akkartik/mu/blob/main/ex2.subx

     1 # Test out the video mode by filling in the screen with pixels.
     2 #
     3 # To build a disk image:
     4 #   ./translate_subx boot.subx ex2.subx   # emits disk.img
     5 # To run:
     6 #   qemu-system-i386 disk.img
     7 # Or:
     8 #   bochs -f bochsrc                      # bochsrc loads disk.img
     9
    10 == code
    11
    12 Entry:
    13   # ecx <- start of video memory
    14   8b/-> *Video-memory-addr 1/r32/ecx
    15
    16   # eax <- final pixel of video memory
    17   8d/copy-address *(ecx + 0x0bffff) 0/r32/eax  # 0xbffff = 1024*768 - 1
    18
    19   # for each pixel in video memory
    20   {
    21     39/compare %eax 1/r32/ecx
    22     7c/jump-if-< break/disp8
    23     # write its column number to it
    24     88/byte<- *eax 0/r32/AL
    25     48/decrement-eax
    26     eb/jump loop/disp8
    27   }
    28
    29   # hang indefinitely
    30   {
    31     eb/jump loop/disp8
    32   }