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/**

 * Timebase software module. Utilizes timer0 to provide a 32bit timebase with

 * millisecond-granularity to the application.

 *

 * @author  Martin Thomas

 * @author  Jimmy Myhrman

 *

 * @date    2006-11-19

 */

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

 * Includes

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

#include <inttypes.h>

#include <avr/io.h>

#include <avr/interrupt.h>

#include <config.h>

#include <drivers/timer/timebase.h>

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

 * Globals

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

volatile uint32_t gMilliSecTick;

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

 * Interrupt Service Routines

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

#if defined(TIMEBASE_NEW_IMPLEMENTATION)

#if defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__)

#if defined(TIMER2)

ISR(TIMER2_COMPA_vect) {

#else //!defined(TIMER2)

ISR(TIMER0_COMPA_vect) {

#endif //defined(TIMER2)

#else //!defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__)

ISR(TIMER2_COMP_vect) {

#endif //defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__)

    gMilliSecTick++;

}

#else //!defined(TIMEBASE_NEW_IMPLEMENTATION)

#if defined(TIMER2)

ISR(SIG_OVERFLOW2) {

    TCNT2 = TIMEBASE_RELOAD;

    gMilliSecTick++;

}

#else

ISR(SIG_OVERFLOW0) {

    TCNT0 = TIMEBASE_RELOAD;

    gMilliSecTick++;

}

#endif

#endif //defined(TIMEBASE_NEW_IMPLEMENTATION)

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

 * Public Functions

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

/**

 * Initializes the timebase. The hardware timer interrupt source will be

 * enabled, but global interrupts need to be enabled by the application.

 */

void Timebase_Init() {

#if defined(TIMEBASE_NEW_IMPLEMENTATION)

#if defined(TIMER2)

    #if defined(__AVR_ATmega8__)

    TCCR2 = (1<<WGM21); // CTC mode

    #if TIMEBASE_PRESCALE == 64

    TCCR2 = (1<<CS22);  // prescaler: 64

    #elif TIMEBASE_PRESCALE == 256

    TCCR2 = (1<<CS22) | (1<<CS21); // prescaler: 256

    #endif

    OCR2 = TIMEBASE_HITS_PER_1MS; // set timer period

    TIFR  |= (1<<OCF2);  // clear ouput compare match flag

    TIMSK |= (1<<OCIE2); // enable output compare match interrupt

    #endif

    #if defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__)

    TCCR2A = (1<<WGM21); // CTC mode

    #if TIMEBASE_PRESCALE == 64

    TCCR2B = (1<<CS22); // prescaler: 64

    #elif TIMEBASE_PRESCALE == 256

    TCCR2B = (1<<CS22)|(1<<CS21);               // prescaler: 256

    #endif

    OCR2A = TIMEBASE_HITS_PER_1MS; // set timer period

    TIFR2  |= (1<<OCF2A);  // clear ouput compare match flag

    TIMSK2 |= (1<<OCIE2A); // enable output compare match interrupt

    #endif

#else /* Use timer0 */

    #if defined(__AVR_ATmega8__)

    #error TIMER0 not supported in ATmega8 with TIMEBASE_NEW_IMPLEMENTATION set!

    #endif

    #if defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__)

    TCCR0A = (1<<WGM01); // CTC mode

    #if TIMEBASE_PRESCALE == 64

    TCCR0B = (1<<CS01) | (1<<CS00); // prescaler: 64

    #elif TIMEBASE_PRESCALE == 256

    TCCR0B = (1<<CS02);             // prescaler: 256

    #endif

    OCR0A = TIMEBASE_HITS_PER_1MS; // set timer period

    TIFR0  |= (1<<OCF0A);  // clear ouput compare match flag

    TIMSK0 |= (1<<OCIE0A); // enable output compare match interrupt

    #endif

#endif

#else //!defined(TIMEBASE_NEW_IMPLEMENTATION)

#if defined(TIMER2)

    #if defined(__AVR_ATmega8__)

    #if TIMEBASE_PRESCALE == 64

    TCCR2 = (1<<CS22);  // prescaler: 64

    #elif TIMEBASE_PRESCALE == 256

    TCCR2 = (1<<CS22) | (1<<CS21); // prescaler: 256

    #endif

    TCNT2 = TIMEBASE_RELOAD; // set initial reload-value

    TIFR  |= (1<<TOV2);  // clear overflow int.

    TIMSK |= (1<<TOIE2); // enable overflow-interrupt

    #endif

    #if defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__)

    #if TIMEBASE_PRESCALE == 64

    TCCR2B = (1<<CS22); // prescaler: 64

    #elif TIMEBASE_PRESCALE == 256

    TCCR2B = (1<<CS22)|(1<<CS21);               // prescaler: 256

    #endif

    TCNT2 = TIMEBASE_RELOAD; // set initial reload-value

    TIFR2  |= (1<<TOV2);  // clear overflow int.

    TIMSK2 |= (1<<TOIE2); // enable overflow-interrupt

    #endif

#else /* Use timer0 */

    #if defined(__AVR_ATmega8__)

    #if TIMEBASE_PRESCALE == 64

    TCCR0 = (1<<CS01) | (1<<CS00);  // prescaler: 64

    #elif TIMEBASE_PRESCALE == 256

    TCCR0 = (1<<CS02);              // prescaler: 256

    #endif

    TCNT0 = TIMEBASE_RELOAD; // set initial reload-value

    TIFR  |= (1<<TOV0);  // clear overflow int.

    TIMSK |= (1<<TOIE0); // enable overflow-interrupt

    #endif

    #if defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__)

    #if TIMEBASE_PRESCALE == 64

    TCCR0B = (1<<CS01) | (1<<CS00); // prescaler: 64

    #elif TIMEBASE_PRESCALE == 256

    TCCR0B = (1<<CS02);             // prescaler: 256

    #endif

    TCNT0 = TIMEBASE_RELOAD; // set initial reload-value

    TIFR0  |= (1<<TOV0);  // clear overflow int.

    TIMSK0 |= (1<<TOIE0); // enable overflow-interrupt

    #endif

#endif

#endif //defined(TIMEBASE_NEW_IMPLEMENTATION)

}

/**

 * Reads the current time.

 *

 * @return

 *      The current time in milliseconds (32bit value).

 */

uint32_t Timebase_CurrentTime(void) {

    uint8_t sreg;

    uint32_t res;

    sreg=SREG;

    cli();

    res = gMilliSecTick;

    SREG=sreg;

    return res;

}

/**

 * Checks how much time has passed since a given timestamp.

 *

 * @param t0

 *      The timestamp.

 * @return

 *      Number of milliseconds that have passed since t0.

 */

uint32_t Timebase_PassedTimeMillis(uint32_t t0) {

    uint8_t sreg;

    uint32_t res;

    sreg=SREG;

    cli();

    res = (uint32_t)(gMilliSecTick-t0);

    SREG=sreg;

    return res;

}