interrupt service routine in FreeRTOS

void EXTI9_5_IRQHandler(void)
{
        long lHigherPriorityTaskWoken = pdFALSE;

        /* Only line 6 is enabled, so there is no need to test which line generated
        the interrupt. */
        EXTI_ClearITPendingBit( EXTI_Line6 );

        /* This interrupt does nothing more than demonstrate how to synchronise a
        task with an interrupt.  First the handler releases a semaphore.
        lHigherPriorityTaskWoken has been initialised to zero. */
        xSemaphoreGiveFromISR( xTestSemaphore, &lHigherPriorityTaskWoken );

        /* If there was a task that was blocked on the semaphore, and giving the
        semaphore caused the task to unblock, and the unblocked task has a priority
         higher than the currently executing task (the task that this interrupt
        interrupted), then lHigherPriorityTaskWoken will have been set to pdTRUE.
        Passing pdTRUE into the following macro call will cause this interrupt to
        return directly to the unblocked, higher priority, task. */
        portEND_SWITCHING_ISR( lHigherPriorityTaskWoken );
}