diff options
| author | Kartik Agaram <vc@akkartik.com> | 2020-12-28 00:12:06 -0800 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2020-12-28 00:12:06 -0800 |
| commit | 437fa654cbba0f29c0a73754803aa00404f0f3a2 (patch) | |
| tree | 648e13ccd1187fcb493c4ad291b286b49942acb1 /baremetal/ex3.hex | |
| parent | 5d2f1c57a58341ee5c793c2eb445159813e37160 (diff) | |
| download | mu-437fa654cbba0f29c0a73754803aa00404f0f3a2.tar.gz | |
7437 - baremetal: draw pixel on keyboard event
It's now clear that our keyboard handler doesn't trigger after the first event.
Diffstat (limited to 'baremetal/ex3.hex')
| -rw-r--r-- | baremetal/ex3.hex | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/baremetal/ex3.hex b/baremetal/ex3.hex new file mode 100644 index 00000000..79fe8cf8 --- /dev/null +++ b/baremetal/ex3.hex @@ -0,0 +1,57 @@ +# Draw pixels in response to keyboard events. +# +# To run, first prepare a realistically sized disk image: +# dd if=/dev/zero of=disk.img count=20160 # 512-byte sectors, so 10MB +# Load the program on the disk image: +# cat baremetal/boot.hex baremetal/ex3.hex |./bootstrap run apps/hex > a.bin +# dd if=a.bin of=disk.img conv=notrunc +# To run: +# qemu-system-i386 disk.img +# Or: +# bochs -f apps/boot.bochsrc # boot.bochsrc loads disk.img + +# main: (address 0x8800) + +# eax <- LFB +8b # copy *rm32 to r32 + 05 # 00/mod/indirect 000/r32/eax 101/rm32/use-disp32 + 28 7f 00 00 # disp32 [label] + +# var read index/ecx: byte = 0 +31 c9 # ecx <- xor ecx; 11/direct 001/r32/ecx 001/rm32/ecx + +# $loop: + # CL = *read index + 8a # copy m8 at r32 to r8 + 0d # 00/mod/indirect 001/r8/cl 101/rm32/use-disp32 + cf 7d 00 00 # disp32 [label] + # CL = *(keyboard buffer + ecx) + 8a # copy m8 at r32 to r8 + 89 # 10/mod/*+disp32 001/r8/cl 001/rm32/ecx + d0 7d 00 00 # disp32 [label] + # if (CL == 0) loop (spin loop) + 80 + f9 # 11/mod/direct 111/subop/compare 001/rm8/CL + 00 # imm8 + 74 ef # loop -17 [label] +# offset 0x19: + # otherwise increment read index + fe # increment byte + 05 # 00/mod/indirect 000/subop/increment 101/rm32/use-disp32 + cf 7d 00 00 # disp32 [label] + # clear top nibble of index (keyboard buffer is circular) + 80 # and byte + 25 # 00/mod/indirect 100/subop/and 101/rm32/use-disp32 + cf 7d 00 00 # disp32 [label] + 0f # imm8 + # print a pixel in fluorescent green + c6 # copy imm8 to m8 at rm32 + 00 # 00/mod/indirect 000/subop 000/rm32/eax + 31 # imm32 + 40 # increment eax + eb dc # loop -36 [label] + +# $break: +e9 fb ff ff ff # hang indefinitely + +# vim:ft=subx |