1 # Test out the video mode by filling in the screen with pixels.
 2 #
 3 # To build a disk image:
 4 #   ./translate_subx_baremetal baremetal/ex2.subx    # emits disk.img
 5 # To run:
 6 #   qemu-system-i386 disk.img
 7 # Or:
 8 #   bochs -f baremetal/boot.bochsrc  # boot.bochsrc loads disk.img
 9 #
10 # Expected output:
11 #   html/baremetal.png
12 
13 # main:  (address 0x8800)
14 
15 == code
16 
17 # ecx <- start of video memory
18 8b/-> *0x7f28 1/r32/ecx
19 
20 # eax <- final pixel of video memory
21 8d/copy-address *(ecx + 0x0bffff) 0/r32/eax  # 0xbffff = 1024*768 - 1
22 
23 # for each pixel in video memory
24 {
25   39/compare %eax 1/r32/ecx
26   7c/jump-if-< break/disp8
27   # write its column number to it
28   88/byte<- *eax 0/r32/AL
29   48/decrement-eax
30   eb/jump loop/disp8
31 }
32 
33 # hang indefinitely
34 {
35   eb/jump loop/disp8
36 }