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Toy OS
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timer.c (428B)

      1 #include "extern.h"
      2 #include "idt.h"
      3 #include "port.h"
      4 
      5 static void timer_callback(struct reg *);
      6 
      7 static uint32_t timer_ticks = 0;
      8 
      9 static void
     10 timer_callback(struct reg *r)
     11 {
     12 	timer_ticks++;
     13 	(void)r;
     14 }
     15 
     16 void
     17 timer_init(uint32_t hz)
     18 {
     19 	uint32_t div = 1193180 / hz;
     20 
     21 	int_add_handler(0, timer_callback);
     22 	outb(P_TIMER_CMD, 0x36);
     23 	outb(P_TIMER_DATA, (uint8_t)(div & 0xff));
     24 	outb(P_TIMER_DATA, (uint8_t)((div >> 8) & 0xff));
     25 }