timer.c

#include "bootpack.h"

#define PIT_CTRL	0x0043
#define PIT_CNT0	0x0040

struct TIMERCTL timerctl;

#define TIMER_FLAGS_ALLOC	1
#define TIMER_FLAGS_USING	2

void init_pit(void) {
	io_out8(PIT_CTRL, 0x34);
	io_out8(PIT_CNT0, 0x9c);
	io_out8(PIT_CNT0, 0x2e);
	timerctl.count = 0;
	int i;
	for (i = 0; i < MAX_TIMER; i++) {
		timerctl.timers0[i].flags = 0;
	}
	struct TIMER *t;
	t = timer_alloc();
	t->timeout = 0xffffffff;
	t->flags = TIMER_FLAGS_USING;
	t->next = 0;
	timerctl.t0 = t;
	timerctl.next = 0xffffffff;
	return;
}

struct TIMER *timer_alloc(void) {
	int i;
	for (i = 0; i < MAX_TIMER; i++) {
		if (timerctl.timers0[i].flags == 0) {
			timerctl.timers0[i].flags = TIMER_FLAGS_ALLOC;
			return &timerctl.timers0[i];
		}
	}
	return 0;
}

void timer_free(struct TIMER *timer) {
	timer->flags = 0;
	return;
}

void timer_init(struct TIMER *timer, struct FIFO32 *fifo, int data) {
	timer->fifo = fifo;
	timer->data = data;
	return;
}

void timer_settime(struct TIMER *timer, unsigned int timeout) {
	timer->timeout = timeout + timerctl.count;
	timer->flags = TIMER_FLAGS_USING;
	int e = io_load_eflags();
	io_cli();
	struct TIMER *t = timerctl.t0;
	if (timer->timeout <= t->timeout) {
		timerctl.t0 = timer;
		timer->next = t;
		timerctl.next = timer->timeout;
		io_store_eflags(e);
		return;
	}
	struct TIMER *s;
	for (;;) {
		s = t;
		t = t->next;
		if (timer->timeout <= t->timeout) {
			s->next = timer;
			timer->next = t;
			io_store_eflags(e);
			return;
		}
	}
	return;
}

void inthandler20(int *esp) {
	char ts = 0;
	io_out8(PIC0_OCW2, 0x60);
	timerctl.count++;
	if (timerctl.next > timerctl.count) {
		return;
	}

	struct TIMER *timer = timerctl.t0;
	for (;;) {
		if (timer->timeout > timerctl.count) {
			break;
		}
		timer->flags = TIMER_FLAGS_ALLOC;
		if (timer != task_timer) {
			fifo32_put(timer->fifo, timer->data);
		} else {
			ts = 1;
		}
		timer = timer->next;
	}

	timerctl.t0 = timer;
	timerctl.next = timer->timeout;
	if (ts != 0) {
		task_switch();
	}
	return;
}