30dayMakeOS/12_day/timer.c

/* 定时器 */

#include "bootpack.h"

#define PIT_CTRL 0x0043
#define PIT_CNT0 0x0040

struct TIMERCTL timerctl;

void init_pit(void)
{
	io_out8(PIT_CTRL, 0x34);
	io_out8(PIT_CNT0, 0x9c);
	io_out8(PIT_CNT0, 0x2e);
	timerctl.count = 0;
	timerctl.timeout = 0;
	return;
}

void inthandler20(int *esp)
{
	io_out8(PIC0_OCW2, 0x60); /* 把IRQ-00信号接收完了的信息通知给PIC */
	timerctl.count++;
	if (timerctl.timeout > 0) { /* 如果已经设定了超时 */
		timerctl.timeout--;
		if (timerctl.timeout == 0) {
			fifo8_put(timerctl.fifo, timerctl.data);
		}
	}
	return;
}

void settimer(unsigned int timeout, struct FIFO8 *fifo, unsigned char data)
{
	int eflags;
	eflags = io_load_eflags();
	io_cli();
	timerctl.timeout = timeout;
	timerctl.fifo = fifo;
	timerctl.data = data;
	io_store_eflags(eflags);
	return;
}