/***************************************************************************
 *   Copyright (C) 01/2019 by Olaf Rempel                                  *
 *   razzor@kopf-tisch.de                                                  *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; version 2 of the License,               *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/
#include <avr/interrupt.h>
#include <avr/io.h>

#include "event.h"
#include "timer.h"

/* *********************************************************************** */

#define TIMER_TIM_INIT()    {   \
                                TCCR0A = 0x00; \
                                TCCR0B = 0x00; \
                                TIMSK0 = (1<<TOIE0); \
                            }

#define TIMER_TIM_ENABLE()  { TCCR0B |= ((1<<CS00) | (1<<CS01)); }
#define TIMER_TIM_DISABLE() { TCCR0B &= ~((1<<CS00) | (1<<CS01)); }
#define TIMER_TIM_RUNNING() (TCCR0B & ((1<<CS00) | (1<<CS01) | (1<<CS02)))
#define TIMER_TIM_RELOAD(x) { TCNT0 = (0xFF - (x)); }
#define TIMER_TIM_VECT      TIMER0_OVF_vect

#define TIMER_DIVISOR       64
#define TIMER_IRQFREQ_MS    1

#define TIMER_MSEC2TICKS(x)     ((x * F_CPU) / (TIMER_DIVISOR * 1000ULL))
#define TIMER_MSEC2IRQCNT(x)    (x / TIMER_IRQFREQ_MS)

static uint16_t m_timers[TIMER_COUNT];
volatile static uint8_t m_timer_ticked;

/* *********************************************************************** */

ISR(TIMER_TIM_VECT)
{
    /* 1ms interrupt */
    TIMER_TIM_RELOAD(TIMER_MSEC2TICKS(TIMER_IRQFREQ_MS));

    m_timer_ticked = 1;
} /* TIM1_OVF_vect */


uint8_t timer_check(uint8_t timer_needed)
{
    if (m_timer_ticked)
    {
        uint8_t i;

        m_timer_ticked = 0;

        for (i = 0; i < TIMER_COUNT; i++)
        {
            if (m_timers[i] > 0)
            {
                m_timers[i]--;
                if (m_timers[i] == 0)
                {
                   event_queue(EVENT_TYPE_TIMER_ELAPSED, i, 0);
                }
                else
                {
                   timer_needed = 1;
                }
            }
        }

        /* stop timer */
        if (timer_needed == 0)
        {
            TIMER_TIM_DISABLE();
        }

        return 1;
    }

    return 0;
} /* timer_check */


void timer_event_handler(event_entry_t * p_event)
{
    if ((p_event->type == EVENT_TYPE_TIMER_SET) &&
        (p_event->num < TIMER_COUNT)
      )
    {
        m_timers[p_event->num] = p_event->value;

        /* start timer if needed */
        if (!TIMER_TIM_RUNNING())
        {
            TIMER_TIM_RELOAD(TIMER_MSEC2TICKS(TIMER_IRQFREQ_MS));
            TIMER_TIM_ENABLE();
        }
    }
} /* timer_event_handler */


uint8_t timer_need_hw_clock(void)
{
    return !!TIMER_TIM_RUNNING();
} /* timer_need_hw_clock */


void timer_init(void)
{
    TIMER_TIM_INIT();
    TIMER_TIM_RELOAD(TIMER_MSEC2TICKS(TIMER_IRQFREQ_MS));
    TIMER_TIM_ENABLE();
} /* timer_init */