kernel/krl_incs/timer.inc

   1 ;----------------------------------------------------------;
   2 ; BOS kernel                     Christoffer Bubach, 2005. ;
   3 ;----------------------------------------------------------;
   4 ;                                                          ;
   5 ;     Function to set up the timer IRQ.                    ;
   6 ;                                                          ;
   7 ;----------------------------------------------------------;
   8
   9 ;-----------------;
  10 ;   variables     ;
  11 ;-----------------;
  12           timer_wait      dd   0                      ; time to wait
  13           timer_counter   dd   0, 0                   ; time since BOS started
  14           call_list       dd   0, 0, 0, 0, 0          ; functions to call
  15
  16
  17 ;---------------------------;
  18 ;      Timer IRQ(0)         ;
  19 ;---------------------------;
  20 timer:
  21           add     dword [timer_counter], 1            ; it's just a 64-bit
  22           adc     dword [timer_counter+4], 0          ; counter since boot.
  23
  24           cmp     [timer_wait], 0                     ; "delay" countdown.
  25           je      .test1
  26           dec     [timer_wait]
  27
  28      .test1:                                          ; checks for calls to
  29           cmp     [call_list], dword 0                ; do before we quit.
  30           je      .test2
  31           call    dword [call_list]
  32      .test2:
  33           cmp     [call_list+4], dword 0
  34           je      .test3
  35           call    dword [call_list+4]
  36      .test3:
  37           cmp     [call_list+8], dword 0
  38           je      .test4
  39           call    dword [call_list+8]
  40      .test4:
  41           cmp     [call_list+12], dword 0
  42           je      .test5
  43           call    dword [call_list+12]
  44      .test5:
  45           cmp     [call_list+16], dword 0
  46           je      .end
  47           call    dword [call_list+16]
  48
  49      .end:
  50           mov     al, 0x20
  51           out     0x20, al
  52           ret
  53
  54
  55
  56 ;------------------------------------------------;
  57 ;   add function for the timer to call           ;
  58 ;                  in:  ebx = function address   ;
  59 ;                  out: eax = 0 if OK            ;
  60 ;------------------------------------------------;
  61 add_timercall:
  62           cmp     [call_list], 0
  63           jne     .test2
  64           mov     [call_list], ebx
  65           jmp     .end
  66      .error:
  67           mov     eax, 1
  68           ret
  69      .test2:
  70           cmp     [call_list+4], 0                    ; since i am so lazy
  71           jne     .test3                              ; and a loop can be
  72           mov     [call_list+4], ebx                  ; rather complicated
  73           jmp     .end                                ; for this stuff, i
  74      .test3:                                          ; check for each one..
  75           cmp     [call_list+8], 0                    ; after all, it's only 5.
  76           jne     .test4
  77           mov     [call_list+8], ebx
  78           jmp     .end
  79      .test4:
  80           cmp     [call_list+12], 0
  81           jne     .test5
  82           mov     [call_list+12], ebx
  83           jmp     .end
  84      .test5:
  85           cmp     [call_list+16], 0
  86           jne     .error
  87           mov     [call_list+16], ebx
  88      .end:
  89           xor     eax, eax
  90           ret
  91
  92
  93
  94 ;-------------------------------------------------;
  95 ;   remove function from the call list            ;
  96 ;                  in:  ebx = function address    ;
  97 ;                  out: eax = 0 if OK             ;
  98 ;-------------------------------------------------;
  99 remove_timercall:
 100           cmp     [call_list], ebx
 101           jne     .test2
 102           mov     [call_list], dword 0
 103           jmp     .end
 104      .error:
 105           mov     eax, 1
 106           ret
 107      .test2:
 108           cmp     [call_list+4], ebx
 109           jne     .test3
 110           mov     [call_list+4], dword 0
 111           jmp     .end
 112      .test3:
 113           cmp     [call_list+8], ebx
 114           jne     .test4
 115           mov     [call_list+8], dword 0
 116           jmp     .end
 117      .test4:
 118           cmp     [call_list+12], ebx
 119           jne     .test5
 120           mov     [call_list+12], dword 0
 121           jmp     .end
 122      .test5:
 123           cmp     [call_list+16], ebx
 124           jne     .error
 125           mov     [call_list+16], dword 0
 126      .end:
 127           xor     eax, eax
 128           ret
 129
 130
 131
 132 ;--------------------------------------------;
 133 ;   delay function                           ;
 134 ;           in:  ecx = 100/second to wait    ;
 135 ;           out: nothing                     ;
 136 ;--------------------------------------------;
 137 delay:
 138           mov     [timer_wait], ecx                   ; mov value to "timer"
 139      .loop:
 140           cmp     [timer_wait], 0
 141           jne     .loop
 142           ret
 143
 144
 145
 146 ;--------------------------------------------;
 147 ;   "active" delay                           ;
 148 ;                                            ;
 149 ; gives the caller a pointer to the counter  ;
 150 ; so that it can check for timeouts etc,     ;
 151 ; itself.                                    ;
 152 ;           in:  ecx = 100/second to wait    ;
 153 ;           out: ecx = pointer to counter    ;
 154 ;--------------------------------------------;
 155 active_delay:
 156           mov     [timer_wait], ecx                   ; mov value to "timer"
 157           mov     ecx, timer_wait                     ; let caller check value
 158           ret
 159
 160
 161
 162 ;------------------------------;
 163 ;     set PIT to 100Hz         ;
 164 ;------------------------------;
 165 set_pit_freq:
 166           push    eax
 167           mov     al, 0x34                            ; set to 100Hz, 0x34 = 00110100b
 168           out     0x43, al
 169           mov     al, 0x9B                            ; lsb    1193180 / 1193
 170           out     0x40, al
 171           mov     al, 0x2E                            ; msb
 172           out     0x40, al
 173           pop     eax
 174           ret