void sleep(int ticks)
{
#if CONFIG_CPU == S3C2440 && defined(BOOTLOADER)
    volatile int counter;
    TCON &= ~(1 << 20); // stop timer 4
    // TODO: this constant depends on dividers settings inherited from
    // firmware. Set them explicitly somwhere.
    TCNTB4 = 12193 * ticks / HZ;
    TCON |= 1 << 21; // set manual bit
    TCON &= ~(1 << 21); // reset manual bit
    TCON &= ~(1 << 22); //autoreload Off
    TCON |= (1 << 20); // start timer 4
    do {
       counter = TCNTO4;
    } while(counter > 0);

#elif defined(CPU_PP) && defined(BOOTLOADER)
    unsigned stop = USEC_TIMER + ticks*10000;
    while (TIME_BEFORE(USEC_TIMER, stop))
        switch_thread(true,NULL);
#else
    sleep_thread(ticks);
#endif
}