mtime.c

VLC Player Source Code

            i_wrap_counts = 0;
        }

        EnterCriticalSection( &date_lock );
#if defined( WIN32 )
        res = INT64_C(1000) *
            (i_wrap_counts * INT64_C(0x100000000) + timeGetTime());
#else
        res = INT64_C(1000) *
            (i_wrap_counts * INT64_C(0x100000000) + GetTickCount());
#endif
        if( i_previous_time > res )
        {
            /* Counter wrapped */
            i_wrap_counts++;
            res += INT64_C(0x100000000) * 1000;
        }
        i_previous_time = res;
        LeaveCriticalSection( &date_lock );
    }
#else
    struct timeval tv_date;

    /* gettimeofday() cannot fail given &tv_date is a valid address */
    (void)gettimeofday( &tv_date, NULL );
    res = (mtime_t) tv_date.tv_sec * 1000000 + (mtime_t) tv_date.tv_usec;
#endif

    return res;
}

/**
 * Wait for a date
 *
 * This function uses select() and an system date function to wake up at a
 * precise date. It should be used for process synchronization. If current date
 * is posterior to wished date, the function returns immediately.
 * \param date The date to wake up at
 */
void mwait( mtime_t date )
{
    /* If the deadline is already elapsed, or within the clock precision,
     * do not even bother the system timer. */
    date -= mprec();

#if defined (HAVE_CLOCK_NANOSLEEP)
    lldiv_t d = lldiv( date, 1000000 );
    struct timespec ts = { d.quot, d.rem * 1000 };

    int val;
    while( ( val = clock_nanosleep( CLOCK_MONOTONIC, TIMER_ABSTIME, &ts,
                                    NULL ) ) == EINTR );
    if( val == EINVAL )
    {
        ts.tv_sec = d.quot; ts.tv_nsec = d.rem * 1000;
        while( clock_nanosleep( CLOCK_REALTIME, 0, &ts, NULL ) == EINTR );
    }
#else

    mtime_t delay = date - mdate();
    if( delay > 0 )
        msleep( delay );

#endif
}

/**
 * More precise sleep()
 *
 * Portable usleep() function.
 * \param delay the amount of time to sleep
 */
void msleep( mtime_t delay )
{
#if defined( HAVE_CLOCK_NANOSLEEP )
    lldiv_t d = lldiv( delay, 1000000 );
    struct timespec ts = { d.quot, d.rem * 1000 };

    int val;
    while( ( val = clock_nanosleep( CLOCK_MONOTONIC, 0, &ts, &ts ) ) == EINTR );
    if( val == EINVAL )
    {
        ts.tv_sec = d.quot; ts.tv_nsec = d.rem * 1000;
        while( clock_nanosleep( CLOCK_REALTIME, 0, &ts, &ts ) == EINTR );
    }

#elif defined( HAVE_KERNEL_OS_H )
    snooze( delay );

#elif defined( WIN32 ) || defined( UNDER_CE )
    for (delay /= 1000; delay > 0x7fffffff; delay -= 0x7fffffff)
        Sleep (0x7fffffff);
    Sleep (delay);

#elif defined( HAVE_NANOSLEEP )
    struct timespec ts_delay;

    ts_delay.tv_sec = delay / 1000000;
    ts_delay.tv_nsec = (delay % 1000000) * 1000;

    while( nanosleep( &ts_delay, &ts_delay ) && ( errno == EINTR ) );

#else
    struct timeval tv_delay;

    tv_delay.tv_sec = delay / 1000000;
    tv_delay.tv_usec = delay % 1000000;

    /* If a signal is caught, you are screwed. Update your OS to nanosleep()
     * or clock_nanosleep() if this is an issue. */
    select( 0, NULL, NULL, NULL, &tv_delay );
#endif
}

/*
 * Date management (internal and external)
 */

/**
 * Initialize a date_t.
 *
 * \param date to initialize
 * \param divider (sample rate) numerator
 * \param divider (sample rate) denominator
 */

void date_Init( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
{
    p_date->date = 0;
    p_date->i_divider_num = i_divider_n;
    p_date->i_divider_den = i_divider_d;
    p_date->i_remainder = 0;
}

/**
 * Change a date_t.
 *
 * \param date to change
 * \param divider (sample rate) numerator
 * \param divider (sample rate) denominator
 */

void date_Change( date_t *p_date, uint32_t i_divider_n, uint32_t i_divider_d )
{
    /* change time scale of remainder */
    p_date->i_remainder = p_date->i_remainder * i_divider_n / p_date->i_divider_num;
    p_date->i_divider_num = i_divider_n;
    p_date->i_divider_den = i_divider_d;
}

/**
 * Set the date value of a date_t.
 *
 * \param date to set
 * \param date value
 */
void date_Set( date_t *p_date, mtime_t i_new_date )
{
    p_date->date = i_new_date;
    p_date->i_remainder = 0;
}

/**
 * Get the date of a date_t
 *
 * \param date to get
 * \return date value
 */
mtime_t date_Get( const date_t *p_date )
{
    return p_date->date;
}

/**
 * Move forwards or backwards the date of a date_t.
 *
 * \param date to move
 * \param difference value
 */
void date_Move( date_t *p_date, mtime_t i_difference )
{
    p_date->date += i_difference;
}

/**
 * Increment the date and return the result, taking into account
 * rounding errors.
 *
 * \param date to increment
 * \param incrementation in number of samples
 * \return date value
 */
mtime_t date_Increment( date_t *p_date, uint32_t i_nb_samples )
{
    mtime_t i_dividend = (mtime_t)i_nb_samples * 1000000 * p_date->i_divider_den;
    p_date->date += i_dividend / p_date->i_divider_num;
    p_date->i_remainder += (int)(i_dividend % p_date->i_divider_num);

    if( p_date->i_remainder >= p_date->i_divider_num )
    {
        /* This is Bresenham algorithm. */
        assert( p_date->i_remainder < 2*p_date->i_divider_num);
        p_date->date += 1;
        p_date->i_remainder -= p_date->i_divider_num;
    }

    return p_date->date;
}

#ifndef HAVE_GETTIMEOFDAY

#ifdef WIN32

/*
 * Number of micro-seconds between the beginning of the Windows epoch
 * (Jan. 1, 1601) and the Unix epoch (Jan. 1, 1970).
 *
 * This assumes all Win32 compilers have 64-bit support.
 */
#if defined(_MSC_VER) || defined(_MSC_EXTENSIONS) || defined(__WATCOMC__)
#   define DELTA_EPOCH_IN_USEC  11644473600000000Ui64
#else
#   define DELTA_EPOCH_IN_USEC  11644473600000000ULL
#endif

static uint64_t filetime_to_unix_epoch (const FILETIME *ft)
{
    uint64_t res = (uint64_t) ft->dwHighDateTime << 32;

    res |= ft->dwLowDateTime;
    res /= 10;                   /* from 100 nano-sec periods to usec */
    res -= DELTA_EPOCH_IN_USEC;  /* from Win epoch to Unix epoch */
    return (res);
}

static int gettimeofday (struct timeval *tv, void *tz )
{
    FILETIME  ft;
    uint64_t tim;

    if (!tv) {
        return VLC_EGENERIC;
    }
    GetSystemTimeAsFileTime (&ft);
    tim = filetime_to_unix_epoch (&ft);
    tv->tv_sec  = (long) (tim / 1000000L);
    tv->tv_usec = (long) (tim % 1000000L);
    return (0);
}

#endif

#endif

/**
 * @return NTP 64-bits timestamp in host byte order.
 */
uint64_t NTPtime64 (void)
{
    struct timespec ts;
#if defined (CLOCK_REALTIME)
    clock_gettime (CLOCK_REALTIME, &ts);
#else
    {
        struct timeval tv;
        gettimeofday (&tv, NULL);
        ts.tv_sec = tv.tv_sec;
        ts.tv_nsec = tv.tv_usec * 1000;
    }
#endif

    /* Convert nanoseconds to 32-bits fraction (232 picosecond units) */
    uint64_t t = (uint64_t)(ts.tv_nsec) << 32;
    t /= 1000000000;


    /* There is 70 years (incl. 17 leap ones) offset to the Unix Epoch.
     * No leap seconds during that period since they were not invented yet.
     */
    assert (t < 0x100000000);
    t |= ((70LL * 365 + 17) * 24 * 60 * 60 + ts.tv_sec) << 32;
    return t;
}