timer_avr.h

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#ifndef DRV_TIMER_AVR_H
#define DRV_TIMER_AVR_H

#include <hw/hw_cpufreq.h>   /* CPU_FREQ */

#include "cfg/cfg_timer.h"   /* CONFIG_TIMER */
#include <cfg/compiler.h>    /* uint8_t */
#include <cfg/macros.h>      /* DIV_ROUND */

#include <avr/io.h>
#include <avr/interrupt.h>

#define TIMER_ON_OUTPUT_COMPARE0  1
#define TIMER_ON_OVERFLOW1        2
#define TIMER_ON_OUTPUT_COMPARE2  3
#define TIMER_ON_OVERFLOW3        4

#define TIMER_DEFAULT TIMER_ON_OUTPUT_COMPARE0 

/*
 * Hardware dependent timer initialization.
 */
#if (CONFIG_TIMER == TIMER_ON_OUTPUT_COMPARE0)

    #define TIMER_PRESCALER      64
    #define TIMER_HW_BITS        8
    #if CPU_AVR_ATMEGA1281 || CPU_AVR_ATMEGA168
        #define DEFINE_TIMER_ISR     SIGNAL(SIG_OUTPUT_COMPARE0A)
    #else
        #define DEFINE_TIMER_ISR     SIGNAL(SIG_OUTPUT_COMPARE0)
    #endif
    #define TIMER_TICKS_PER_SEC  1000
    #define TIMER_HW_CNT         OCR_DIVISOR

    typedef uint8_t hptime_t;

    INLINE hptime_t timer_hw_hpread(void)
    {
        return TCNT0;
    }

#elif (CONFIG_TIMER == TIMER_ON_OVERFLOW1)

    #define TIMER_PRESCALER      1
    #define TIMER_HW_BITS        8

    #define TIMER_HW_CNT         (1 << TIMER_HW_BITS)
    #define DEFINE_TIMER_ISR     SIGNAL(SIG_OVERFLOW1)
    #define TIMER_TICKS_PER_SEC  DIV_ROUND(TIMER_HW_HPTICKS_PER_SEC, TIMER_HW_CNT)

    typedef uint16_t hptime_t;

    INLINE hptime_t timer_hw_hpread(void)
    {
        return TCNT1;
    }

#elif (CONFIG_TIMER == TIMER_ON_OUTPUT_COMPARE2)

    #define TIMER_PRESCALER      64
    #define TIMER_HW_BITS        8
    #if CPU_AVR_ATMEGA1281 || CPU_AVR_ATMEGA168
        #define DEFINE_TIMER_ISR     SIGNAL(SIG_OUTPUT_COMPARE2A)
    #else
        #define DEFINE_TIMER_ISR     SIGNAL(SIG_OUTPUT_COMPARE2)
    #endif
    #define TIMER_TICKS_PER_SEC  1000

    #define TIMER_HW_CNT         OCR_DIVISOR

    typedef uint8_t hptime_t;

    INLINE hptime_t timer_hw_hpread(void)
    {
        return TCNT2;
    }

#elif (CONFIG_TIMER == TIMER_ON_OVERFLOW3)

    #define TIMER_PRESCALER      1
    #define TIMER_HW_BITS        8

    #define TIMER_HW_CNT         (1 << TIMER_HW_BITS)
    #define DEFINE_TIMER_ISR     SIGNAL(SIG_OVERFLOW3)
    #define TIMER_TICKS_PER_SEC  DIV_ROUND(TIMER_HW_HPTICKS_PER_SEC, TIMER_HW_CNT)

    typedef uint16_t hptime_t;

    INLINE hptime_t timer_hw_hpread(void)
    {
        return TCNT3;
    }

#else

    #error Unimplemented value for CONFIG_TIMER
#endif /* CONFIG_TIMER */


#define TIMER_HW_HPTICKS_PER_SEC  DIV_ROUND(CPU_FREQ, TIMER_PRESCALER)

#define OCR_DIVISOR  (DIV_ROUND(DIV_ROUND(CPU_FREQ, TIMER_PRESCALER), TIMER_TICKS_PER_SEC) - 1)

#define timer_hw_irq() do {} while (0)

#define timer_hw_triggered() (true)

void timer_hw_init(void);

#endif /* DRV_TIMER_AVR_H */