/*******************************************************************************************************************
 *File Name   : watchdog.c
 *Description : the file is driver for watchdog
 *Date	    : 2008/06/16
 *Author        : yuanguiyou
 --History:
 ------------------------------------------------------------------------------------------------------------------
 *change info:
 
 *******************************************************************************************************************/
#include <avr/wdt.h>
#include <avr/io.h>

#include "watchdog.h"


/*!
 * \addtogroup xgNutArchAvrDevWatchDog
 */
/*@{*/

/*!
 * \brief Watchdog oscillator frequency.
 */
#ifndef WDT_FREQ
#define WDT_FREQ    1165000
#endif

static u16 nested;
static u08 wdt_div;


/*!
 * \brief Start the AVR hardware watch dog timer.
 *
 * For portability, applications should use the platform independent 
 * \ref xgWatchDog "Watchdog Driver API".
 *
 * \param ms Desired watchdog timeout in milliseconds.
 *
 * \return The actual watchdog timeout.
 */
u32 WatchDogStart(u32 ms)
{
    u32 ticks;

    wdt_reset();

    ticks = ((WDT_FREQ / 1000UL) * ms) >> 14;
    for (wdt_div = 0; wdt_div < 7 && ticks; wdt_div++) {
        ticks >>= 1;
    }
    wdt_enable(wdt_div);
    
    nested = 1;

    return (16384UL << wdt_div) / (WDT_FREQ / 1000UL);
}

/*!
 * \brief Re-start the AVR hardware watch dog timer.
 *
 * For portability, applications should use the platform independent 
 * \ref xgWatchDog "Watchdog Driver API".
 */
void WatchDogRestart(void)
{
    wdt_reset();
}

/*!
 * \brief Disable the AVR hardware watch dog timer.
 *
 * For portability, applications should use the platform independent 
 * \ref xgWatchDog "Watchdog Driver API".
 */
void WatchDogDisable(void)
{
    if (nested) {
        nested++;
    }
    wdt_disable();
}

/*!
 * \brief Enable the AVR hardware watch dog timer.
 *
 * For portability, applications should use the platform independent 
 * \ref xgWatchDog "Watchdog Driver API".
 */
void WatchDogEnable(void)
{
    if (nested > 1 && --nested == 1) {
        wdt_enable(wdt_div);
    }
}

/*@}*/