7462 - SubX version of baremetal/ex2.subx

1 files changed, 35 insertions, 0 deletions

diff --git a/baremetal/ex2.subx b/baremetal/ex2.subx
new file mode 100644
index 00000000..1a0f429d
--- /dev/null
+++ b/baremetal/ex2.subx
@@ -0,0 +1,35 @@
+# Test out the video mode by filling in the screen with pixels.
+#
+# To build a disk image:
+#   ./translate_subx_baremetal baremetal/ex2.subx    # emits disk.img
+# To run:
+#   qemu-system-i386 disk.img
+# Or:
+#   bochs -f baremetal/boot.bochsrc  # boot.bochsrc loads disk.img
+
+# main:  (address 0x8800)
+
+== code
+
+# ecx <- start of video memory
+8b/-> 0/mod/indirect 5/rm32/use-disp32 0x7f28/disp32/video-memory  1/r32/ecx
+
+# eax <- final pixel of video memory
+8d/copy-address *(ecx + 0x0bffff) 0/r32/eax  # 0xbffff = 1024*768 - 1
+
+# for each pixel in video memory
+{
+  39/compare %eax 1/r32/ecx
+  7c/jump-if-< break/disp8
+  # write its column number to it
+  88/byte<- *eax 0/r32/AL
+  48/decrement-eax
+  eb/jump loop/disp8
+}
+
+# hang indefinitely
+{
+  eb/jump loop/disp8
+}
+
+# vim:ft=subx