kernel/int/idt.asm

   1 ;----------------------------------------------------------;
   2 ; BOS kernel                Christoffer Bubach, 2003-2005. ;
   3 ;----------------------------------------------------------;
   4 ;                                                          ;
   5 ;    set/modify IDT entries                                ;
   6 ;                                                          ;
   7 ;----------------------------------------------------------;
   8
   9
  10
  11 ;--------------------------------------------------;
  12 ;     set up IDT                                   ;
  13 ; in:  esi = pointer to "unhandled int"-function.  ;
  14 ;--------------------------------------------------;
  15 init_idt:
  16         push   eax
  17         push   ecx
  18
  19         xor    ecx, ecx
  20     .l1:
  21         mov    eax, esi                               ; loop full IDT and
  22         mov    [(0x6c00+ecx)], ax                     ; set to one ISR
  23         add    ecx, 2
  24
  25         mov    dword [(0x6c00+ecx)], 0x8E000008       ; 0x6c00 is where
  26         add    ecx, 4                                 ; we put the IDT
  27
  28         mov    eax, esi
  29         shr    eax, 16
  30         mov    [(0x6c00+ecx)], ax
  31         add    ecx, 2
  32
  33         cmp    ecx, 0x800                             ; 256 ints
  34         jb     .l1                                    ; * 8 bytes each
  35
  36         pop    ecx
  37         pop    eax
  38         ret
  39
  40
  41
  42 ;--------------------------------------;
  43 ;  modify IDT, set any int             ;
  44 ;     in: cl  = int number             ;
  45 ;      edi = int function pointer      ;
  46 ;--------------------------------------;
  47 set_int:
  48                 push   eax
  49                 push   ecx
  50
  51                 mov    al, 8                                  ; 8 bytes for each int
  52                 mul    cl                                     ; cl * al = ax
  53                 movzx  ecx, ax                                ; ecx = IDT offset
  54                 shr    ecx, 1                                 ; 1/2 for dword list
  55                 mov    dword [(idt_list+ecx)], edi            ; add to dword int list
  56                 movzx  ecx, ax                                ; ecx = IDT offset
  57
  58                 mov    eax, edi
  59                 mov    [(0x6c00+ecx)], ax
  60                 add    ecx, 2
  61
  62                 mov    dword [(0x6c00+ecx)], 0x8E000008
  63                 add    ecx, 4
  64
  65                 mov    eax, edi
  66                 shr    eax, 16
  67                 mov    [(0x6c00+ecx)], ax
  68
  69                 pop    ecx
  70                 pop    eax
  71                 ret
  72
  73
  74
  75 ;------------------------------------------------;
  76 ;   get int address                              ;
  77 ;      in:  cl    = int number                   ;
  78 ;      out: esi = address or 0 if none present   ;
  79 ;------------------------------------------------;
  80 get_int:
  81                 push   eax
  82
  83                 mov    eax, 4                                 ; 4 bytes for each address
  84                 mul    cl                                     ; cl * al = ax
  85                 mov    esi, idt_list
  86                 add    esi, eax
  87
  88                 pop    eax
  89                 ret
  90
  91
  92
  93
  94 ;----------------------------------------;
  95 ;   sets ints from list                  ;
  96 ;      in:  esi = pointer to int list    ;
  97 ;----------------------------------------;
  98 set_idt_list:
  99                 push   eax
 100                 push   edi
 101
 102                 xor    ecx, ecx
 103         .l1:
 104                 lodsd
 105                 or     eax, eax
 106                 jz     .next
 107                 mov    edi, eax
 108                 call   set_int
 109         .next:
 110                 inc    ecx
 111                 cmp    ecx, 0x100
 112                 jb     .l1
 113
 114                 pop    edi
 115                 pop    eax
 116                 ret
 117
 118
 119
 120 ;------------------------------;
 121 ;   list of idt entries.       ;
 122 ;        0 = not handled       ;
 123 ;------------------------------;
 124 idt_list:   dd   isr00
 125             dd   isr01
 126             dd   isr02
 127             dd   isr03
 128             dd   isr04
 129             dd   isr05
 130             dd   isr06
 131             dd   isr07
 132             dd   isr08
 133             dd   isr09
 134             dd   isr0A
 135             dd   isr0B
 136             dd   isr0C
 137             dd   isr0D
 138             dd   isr0E
 139             dd   0
 140             dd   isr10
 141             dd   isr11
 142             dd   isr12
 143             dd   isr13
 144    times 12 dd   0                                    ; 12 unused ints
 145             dd   isr20
 146             dd   isr21
 147    times 16 dd   0                                    ; 16 unused ints
 148             dd   isr32                                ; First free and BOS system interrupt.
 149   times 205 dd   0                                    ; 205 unused ints