diff options
Diffstat (limited to 'baremetal')
| -rw-r--r-- | baremetal/ex2.hex | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/baremetal/ex2.hex b/baremetal/ex2.hex index d3fbec8d..3e3df877 100644 --- a/baremetal/ex2.hex +++ b/baremetal/ex2.hex @@ -1,5 +1,4 @@ -# Test out the video mode without running afoul of video memory banking. Fill -# just the first row with pixels. +# Test out the video mode by filling in the screen with pixels. # # To run, first prepare a realistically sized disk image: # dd if=/dev/zero of=disk.img count=20160 # 512-byte sectors, so 10MB @@ -8,20 +7,32 @@ # dd if=a.bin of=disk.img conv=notrunc # To run: # qemu-system-i386 disk.img -# Or: +# Or: (temporarily doesn't work) # bochs -f apps/boot.bochsrc # boot.bochsrc loads disk.img # main: (address 0x8000) -b8 ff 04 0a 00 # eax <- 0xa0000 (start of video RAM) + 0x4ff (1279 = final pixel in first row) + +# ecx <- LFB +8b # copy *rm32 to r32 + 0d # 00/mod/indirect 001/r32/ecx 101/rm32/use-disp32 + 68 7d 00 00 # disp32 + +# eax <- LFB + 0x13ffff (1280*1024 - 1) +8d # copy-address rm32 to r32 + 81 # 10/mod/*+disp32 000/r32/eax 001/rm32/ecx + ff ff 13 00 # disp32 + # $loop: -3d 00 00 0a 00 # compare eax with 0xa0000 +# if (eax < ecx) break +39 # compare rm32 with r32 + c8 # 11/mod/direct 001/r32/ecx 000/rm32/eax 7c 06 # break if < # *eax <- 0xff c6 # copy imm8 to m8 at r32 00 # 00/mod/indirect 000/subop 000/eax 31 # imm32 48 # decrement eax -eb f3 # loop = -13 bytes +eb f6 # loop to -10 bytes # $break: e9 fb ff ff ff # hang indefinitely |