kernel/kernel.asm

   1 ;-------------------------------------------------------;
   2 ;                     BOS kernel                        ;
   3 ;-------------------------------------------------------;
   4 ;    BOS 32-bit kernel, expects to be loaded at 64kb    ;
   5 ;    in mem.   Small amount of 16-bit code included.    ;
   6 ;                                                       ;
   7 ;      For any comments on this code, mail me.          ;
   8 ;   http://bos.asmhackers.net/   asmhacker@gmail.com    ;
   9 ;                                                       ;
  10 ;             by: Christoffer Bubach, 2003-2005         ;
  11 ;-------------------------------------------------------;
  12 use16
  13 org 0x8000
  14
  15 ;---------------------------;
  16 ;  jump to starting point   ;
  17 ;---------------------------;
  18           jmp     start
  19
  20 ;----------------------------------------;
  21 ;     16-bit include files               ;
  22 ;----------------------------------------;
  23           include  'realmode/a20.inc'                 ; Function to set the a20-gate.
  24           include  'realmode/gdt.inc'                 ; Global Description Table.
  25           include  'realmode/idt.inc'                 ; The Interrupt Description Table.
  26           include  'realmode/mem.inc'                 ; Get memory size.
  27           include  'realmode/variables.inc'           ; For/from realmode.
  28           include  'realmode/do_all_16bit.inc'        ; Save "go back to 16-bit"-info.
  29
  30
  31
  32 ;--------------------------;
  33 ;   16-bit entry point     ;
  34 ;--------------------------;
  35 start:
  36           cli
  37           mov     ax, cs
  38           mov     ds, ax
  39                                                       ; fasm is more strict about
  40           xor     eax, eax                            ; "org 0x10000" then nasm, so
  41           mov     es, ax                              ; i have to do -0x10000 from
  42           mov     fs, ax                              ; all variable addresses while
  43           mov     gs, ax                              ; in realmode.
  44           sti
  45
  46           call    enable_a20
  47           call    do_all_16bit                        ; ...  :P
  48
  49           cli
  50           mov     ax, cs                              ; save cs
  51           mov     [realmode_cs], ax           ; in variables.inc
  52
  53           lgdt    [gdtr]                      ; Load the GDT descriptor
  54           lidt    [idtr]                      ; Load the IDT descriptor
  55
  56           mov     eax, cr0
  57           or      al, 1
  58           mov     cr0, eax
  59
  60           jmp     pword 0x08:flush                    ; dword in nasm
  61
  62
  63
  64 ;--------------------------;
  65 ;   32-bit entry point     ;
  66 ;--------------------------;
  67 use32
  68 flush:
  69           mov     ax, 0x10                            ; refresh all segment registers
  70           mov     ds, ax
  71           mov     es, ax
  72           mov     fs, ax
  73           mov     gs, ax
  74           mov     ss, ax
  75           mov     esp, 0xFFFC
  76
  77           call    bos_init                            ; fix everything
  78
  79           mov     bx, 0x04B1                          ; start the shell
  80           call    setcursor
  81           mov     esi, bos_shell
  82           mov     bl, 0x07
  83           call    print
  84           call    init_cmd
  85           jmp     shell
  86
  87           ;int     0x32
  88
  89      .hang:
  90           cli
  91           hlt
  92           jmp     .hang                               ; hang, just in case..
  93
  94
  95 ;----------------------------------------;
  96 ;     32-bit include files               ;
  97 ;----------------------------------------;
  98           include  'krl_incs/idt.inc'                 ; The Interrupt Description Table.
  99           include  'krl_incs/text.inc'                ; The default textmode functions.
 100           include  'krl_incs/bos_init.inc'            ; Function that starts up BOS
 101           include  'krl_incs/en_mess.inc'             ; All strings in english (soon).
 102           include  'krl_incs/rmode_int.inc'           ; Get back to realmode and do an INT.
 103           include  'krl_incs/pic.inc'                 ; PIC rutines.
 104           include  'krl_incs/sys_ints.inc'            ; System specific interrupts.
 105           include  'krl_incs/keyboard.inc'            ; Keyboard ISR.
 106           include  'krl_incs/keymap.inc'              ; Keymap(s).
 107           include  'krl_incs/shell.inc'               ; File with shell/kernel monitor functions.
 108           include  'krl_incs/commands.inc'            ; Command table, for valid shell commands.
 109           include  'krl_incs/isr.inc'                 ; Interrupt Service Rutines.
 110           include  'krl_incs/debug.inc'               ; Print contents of all regs and hang.
 111           include  'krl_incs/cmos.inc'                ; To get CMOS data.
 112           include  'krl_incs/time_date.inc'           ; Print time and date.
 113           include  'krl_incs/timer.inc'               ; Timer IRQ.
 114           include  'krl_incs/vga.inc'                 ; VGA functions.
 115         ;  include  'krl_incs/font8x16.inc'            ; Standard font.
 116           include  'krl_incs/dma.inc'                 ; DMA code.
 117           include  'krl_incs/fdc.inc'                 ; Floppy code.
 118           include  'krl_incs/mario.inc'               ; Mario sprite.
 119           include  'krl_incs/pc_speaker.inc'          ; PC speaker.
 120           include  'krl_incs/mem.inc'                 ; Memory allocation and freeing.