diff options
| -rw-r--r-- | README.md | 3 | ||||
| -rw-r--r-- | apps/boot.hex | 55 |
2 files changed, 49 insertions, 9 deletions
diff --git a/README.md b/README.md index 34070bbc..f39cd10b 100644 --- a/README.md +++ b/README.md @@ -220,3 +220,6 @@ claims of completeness: - Wikipedia on BIOS interfaces: [Int 10h](https://en.wikipedia.org/wiki/INT_10H), [Int 13h](https://en.wikipedia.org/wiki/INT_13H). - [Some tips on programming bootloaders](https://stackoverflow.com/questions/43786251/int-13h-42h-doesnt-load-anything-in-bochs/43787939#43787939) by Michael Petch. +- [xv6, the port of Unix Version 6 to x86 processors](https://github.com/mit-pdos/xv6-public) +- Some tips on handling keyboard interrupts by [Alex Dzyoba](https://alex.dzyoba.com/blog/os-interrupts) + and [Michael Petch](https://stackoverflow.com/questions/37618111/keyboard-irq-within-an-x86-kernel). diff --git a/apps/boot.hex b/apps/boot.hex index 111c6cc4..d8c80e79 100644 --- a/apps/boot.hex +++ b/apps/boot.hex @@ -68,7 +68,7 @@ # this is from https://github.com/mit-pdos/xv6-public/blob/master/bootasm.S # seta20.1: e4 64 # al <- port 0x64 - a8 02 # set zf if bit 1 (second-least) is not set + a8 02 # set zf if bit 1 (second-least significant) is not set 75 fa # if zf not set, goto seta20.1 (-6) b0 d1 # al <- 0xd1 @@ -77,7 +77,7 @@ # 30: # seta20.2: e4 64 # al <- port 0x64 - a8 02 # set zf if bit 1 (second-least) is not set + a8 02 # set zf if bit 1 (second-least significant) is not set 75 fa # if zf not set, goto seta20.2 (-6) b0 df # al <- 0xdf @@ -173,13 +173,17 @@ e9 fb ff # loop forever 0f 01 1d # lidt 00/mod/indirect 011/subop 101/rm32/use-disp32 00 7f 00 00 # *idt_descriptor + # enable keyboard IRQ + b0 fd # al <- 0xfd # enable just IRQ1 + e6 21 # port 0x21 <- al + # initialization is done; enable interrupts fb - e9 25 00 00 00 # jump to 0x7d00 + e9 21 00 00 00 # jump to 0x7d00 # padding -# db: - 00 00 00 00 00 +# df: + 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 @@ -211,8 +215,35 @@ e9 fb ff ff ff # loop forever # padding # 121: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 -00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 -00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 + +# 130: +# keyboard interrupt handler: + # prologue + fa # disable interrupts + 60 # push all registers to stack + # acknowledge interrupt + b0 20 # al <- 0x20 + e6 20 # port 0x20 <- al + # read keyboard status (IBF from https://web.archive.org/web/20040604041507/http://panda.cs.ndsu.nodak.edu/~achapwes/PICmicro/keyboard/atkeyboard.html) + e4 64 # al <- port 0x64 + a8 01 # set zf if bit 0 (least significant) is not set + 74 00 # if bit 0 is not set, skip to epilogue HERE + # read keycode into eax + 31 c0 # eax <- xor eax; 11/direct 000/r32/eax 000/rm32/eax + e4 60 # al <- port 0x60 + # print eax to top-left of screen (*0xb8000) + 89 # copy r32 to rm32 + 05 # 00/mod/indirect 000/r32/eax 101/rm32/use-disp32 + # disp32 + 00 80 0b 00 + # epilogue + 61 # pop all registers + fb # enable interrupts + cf # iret + +# padding +# 149 + 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 @@ -244,14 +275,20 @@ e9 fb ff ff ff # loop forever 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 -# offset 8 +# entry 8: clock? 20 7d # target[0:16] = null interrupt handler 08 00 # segment selector (gdt_code) 00 # unused 8e # 1/p 00/dpl 0 1110/type/32-bit-interrupt-gate 00 00 # target[16:32] -00 00 00 00 00 00 00 00 +# entry 9: keyboard? + 30 7d # target[0:16] = keyboard interrupt handler + 08 00 # segment selector (gdt_code) + 00 # unused + 8e # 1/p 00/dpl 0 1110/type/32-bit-interrupt-gate + 00 00 # target[16:32] + 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |