ardupilot/APMrover2/compat.pde

static void delay(uint32_t ms)
{
    hal.scheduler->delay(ms);
}

static void mavlink_delay(uint32_t ms)
{
    hal.scheduler->delay(ms);
}

static uint32_t millis()
{
    return hal.scheduler->millis();
}

static uint32_t micros()
{
    return hal.scheduler->micros();
}