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clock.c

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/*!     \file kernel/clock.c
 *      \brief The system clock manager.
 *      \author Andrea Righi <drizzt@inwind.it>
 *      \date Last update: 2003-08-23
 *      \note Copyright (&copy;) 2003 Andrea Righi
 */

#include <const.h>

#include <arch/i386.h>

#include <kernel/floppy.h>
#include <kernel/task.h>

#include <kernel/clock.h>

//! System ticks.
volatile dword ticks = 0;

//! \brief Initialize channel 0 of the 8253A timer
void init_clock()
{
        dword IF = GET_IF();

        disable();

        outportb(TIMER_MODE, SQUARE_WAVE);      // set timer on
        outportb(TIMER0, TIMER_COUNT & 0xFF);   // timer low byte
        outportb(TIMER0, TIMER_COUNT >> 8);     // timer high byte

        SET_IF(IF);
}

//! \brief Reset the clock for rebooting
void stop_clock()
{
        dword IF = GET_IF();


        disable();

        outportb(TIMER_MODE, SQUARE_WAVE);      // set timer on
        outportb(TIMER0, 0);                    // timer low byte
        outportb(TIMER0, 0);                    // timer high byte

        SET_IF(IF);
}

//! \brief Delay some milliseconds
//! \param millisec How many milliseconds you want to delay.
void delay(dword millisec)
{
        dword count, elapsed;
        dword IF = GET_IF();

        // Start timer //
        elapsed = 0;

        while (elapsed < millisec)
        {
                // Poll ticks in memory //
                count = ticks;

                // Auto-sleep //
                enable();
                idle();

                // Update elapsed time //
                elapsed += (ticks - count)*1000/HZ;
        }

        SET_IF(IF);
}

//! \brief Initialize a timeout variable.
//! \param t The timeout variable.
//! \param millisec
//!     How many milliseconds have to elapse before the timeout occurs.
void set_timeout(timeout_t *t, unsigned int millisec)
{
        t->start_ticks = ticks;
        t->ticks_to_wait = millisec * HZ / 1000;
}

//! \brief Check if a timeout has been elapsed.
//! \param t The timeout variable.
bool is_timeout(timeout_t *t)
{
// Check if a timeout has gone                                          //
        uint32_t elapsed;
        elapsed = ticks - t->start_ticks;
        return( elapsed >= t->ticks_to_wait );
}

//! \brief Return the system ticks.
//! \return The system ticks.
dword sys_get_ticks()
{
        return(ticks);
}

//! \brief This is a task that occurs at every clock tick.
/*!
 *      Into this routine you can put every periodical task.\n
 *      You can change the frequency of the ticks changing the value
 *      of the #HZ definition.\n
 *      This thread is invoked at every clock tick by the dispatcher().
 */
void clock_thread()
{
        ticks++;
        floppy_thread();
}

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