reboot

README.md

@@ -20,6 +20,8 @@ Hello world programs that run without an operating system.
         1.  [pixel](bios_pixel.S)
             1.  [pixel line](bios_pixel_line.S)
         1.  [keyboard](bios_keyboard.S)
+            1.  [keyboard loop](bios_keyboard_loop.S)
+    1.  [reboot](reboot.S)
     1.  [Not testable in userland](not-testable-in-userland.md)
         1.  [Segment registers real mode](segment_registers_real_mode.S)
             1 [SS (TODO)](ss.S)

TODO.md

@@ -9,8 +9,12 @@
 
     - wbinvd
     - outb inb
-    - lgdtl, paging http://stackoverflow.com/questions/21128311/the-physical-address-of-global-descriptor-table
-    - lidtl, interrupts
+    - lgdtl, paging http://stackoverflow.com/questions/21128311/the-physical-address-of-global-descriptor-table http://stackoverflow.com/questions/7415515/problem-accessing-control-registers-cr0-cr2-cr3
+    - lidtl, interrupts, IDTR
+        - https://en.wikipedia.org/wiki/Double_fault
+        - https://en.wikipedia.org/wiki/Triple_fault
+        - http://stackoverflow.com/questions/1817577/what-does-int-0x80-mean-in-assembly-code
+        - http://stackoverflow.com/questions/12464329/is-it-possible-to-make-a-custom-interrupt-in-assembly
     - WRMSR https://en.wikipedia.org/wiki/Model-specific_register http://x86.renejeschke.de/html/file_module_x86_id_326.html
 
 -   Segment registers on protected mode. Then try to answer all of:
@@ -60,6 +64,7 @@
 -   play with hardware
 
     -   keyboard through interrupt (high level int 16 bios done)
+        - keyboard protected mode: http://stackoverflow.com/questions/219120/x86-assembly-protected-mode-keyboard-access
     -   set a pixel on screen in protected mode http://stackoverflow.com/questions/14419088/assembly-draw-a-pixel-on-the-screen-in-protected-mode
     -   USB
     -   networking

bios_keyboard_loop.S

@@ -0,0 +1,14 @@
+/*
+This just begs for a non-minimal for-fun infinite loop version.
+
+Do try Ctrl-key combinations.
+*/
+
+#include "common.h"
+BEGIN
+start:
+    mov $0x00, %ah
+    int $0x16
+    PUTC(%al)
+    jmp start
+END

interrupt.S

@@ -0,0 +1,24 @@
+/*
+Minimal interrupt example.
+
+Upon division by zero, the interrupt handler is run,
+and it prints the character 'A' to screen.
+
+TODO: is STI not needed because this interrupt is not maskable?
+
+TODO: use IDTR. Is initial value guaranteed?
+*/
+
+#include "common.h"
+BEGIN
+    CLEAR
+    movw $handler, 0x00
+    movw $0x00, 0x02
+    mov $0x00, %ax
+    div %ax
+    jmp fail
+handler:
+    PUTC($0x61)
+fail:
+    hlt
+END

interrupt_keyboard.S

@@ -0,0 +1,16 @@
+/*
+TODO get working
+*/
+
+#include "common.h"
+BEGIN
+    CLEAR
+    movw $handler, 0x04
+    movw $0x00, 0x06
+    sti
+loop:
+    jmp loop
+handler:
+    PUTC($0x61)
+jmp loop
+END

reboot.S

@@ -0,0 +1,12 @@
+/*
+http://stackoverflow.com/questions/32682152/how-to-reboot-in-x86-assembly-from-16-bit-real-mode
+
+Infinite reboot loop on emulator!
+
+TODO why does it work?
+*/
+
+#include "common.h"
+BEGIN
+ljmpw $0xF000, $0XFFF0
+END