/*
 * (C) Copyright 2014 Leo C. <erbl259-lmu@yahoo.de>
 *
 * SPDX-License-Identifier:	GPL-2.0
 */

#include "timer.h"
#include <avr/interrupt.h>
#include <util/atomic.h>
#include "time.h"

/* timer interrupt/overflow counter */
/* counts up every ms. */
static volatile
uint32_t timestamp;

/*
 * 1000Hz timer interrupt generated by OC4A
 */
ISR(TIMER4_COMPA_vect)
{
	static int_fast8_t tick_10ms;
	static int_fast8_t tick_1s;
	int_fast8_t i, j;

	extern void disk_timerproc(void);

	OCR4A += F_CPU / 1000;	/* 1000Hz interval */

	timestamp++;

	i = tick_10ms + 1;
	if (i == 10) {
		Stat |= S_10MS_TO;

		/* Drive timer procedure of low level disk I/O module */
		disk_timerproc();

		j = tick_1s - 1;
		if (j == 0) {
			system_tick();
			j = 100;
		}
		tick_1s = j;
		i = 0;
	}
	tick_10ms = i;
}


/*--------------------------------------------------------------------------*/

uint32_t get_timer(uint32_t base)
{
	uint32_t ret;
	ATOMIC_BLOCK(ATOMIC_FORCEON)
	{
		ret = timestamp;
	}
	return ret - base;
}