gistfile1.txt

/* This function checks if we need to enter the TITL mode.
 *
 * The TILT mode is entered if we detect that between two invocations of the
 * timer interrupt, a negative amount of time, or too much time has passed.
 * Note that we expect that more or less just 100 milliseconds will pass
 * if everything is fine. However we'll see a negative number of a
 * difference bigger than SENTINEL_TILT_TRIGGER milliseconds if one of the
 * following happens:
 *
 * 1) The Sentiel process for some time is blocked, for every kind of
 * random reason: the load is huge, the computer was freezed for some time
 * in I/O or alike, the process was stopped by a signal. Everything.
 * 2) The system clock was altered significantly.
 *
 * Under both this conditions we'll see everything as timed out and failing
 * without good reasons. Instead we enter the TILT mode and wait
 * for SENTIENL_TILT_PERIOD to elapse before starting to act again.
 *
 * During TILT time we still collect information, we just do not act. */
void sentinelCheckTiltCondition(void) {
    mstime_t now = mstime();
    mstime_t delta = now - sentinel.previous_time;

    if (delta < 0 || delta > SENTINEL_TILT_TRIGGER) {
        sentiel.tilt = 1;
        sentiel.tilt_start_time = mstime();
    }
    sentinel.previous_time = mstime();
}