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#include "timer.h"
#include "idt.h"
#include <core/sys.h>
#include <core/monitor.h>
static uint32_t tick = 0, frequency = 0, uptime = 0;
/* Called when IRQ0 fires. Updates the uptime variable.
DOES NOT provoke a task switch. The task switch is called in idt.c (IRQ handler). */
void timer_callback(struct registers *regs) {
tick++;
if (tick == frequency) {
uptime++;
tick = 0;
}
}
/* Accessor function to get machine uptime. */
uint32_t timer_uptime() { return uptime; }
/* Accessor function, gets uptime in miliseconds. */
uint32_t timer_time() {
return (uptime * 1000) + (tick * 1000 / frequency);
}
/* Called by kmain. Sets up the PIT and the IRQ0 handler. */
void timer_init(uint32_t freq) {
frequency = freq;
idt_handleIrq(0, timer_callback);
uint32_t divisor = 1193180 / freq;
outb(0x43, 0x36); //Command byte
uint8_t l = (divisor & 0xFF), h = (divisor >> 8);
outb(0x40, l);
outb(0x40, h);
monitor_write("[PIT] ");
}
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