Detect GPS week rollover in ZDA sentences. All regression tests pass.

1 files changed, 21 insertions, 23 deletions

diff --git a/driver_nmea.c b/driver_nmea.c
index 8d08303f..14345711 100644
--- a/driver_nmea.c
+++ b/driver_nmea.c
@@ -676,30 +676,28 @@ static gps_mask_t processGPZDA(int c UNUSED, char *field[],
 	    gpsd_report(LOG_WARN, "malformed ZDA month: %s\n",  field[3]);
 	} else if ( (1 > mday ) || (31 < mday ) ) {
 	    gpsd_report(LOG_WARN, "malformed ZDA day: %s\n",  field[2]);
-	} else if (century > session->context->century) {
-	    /*
-	     * This mismatch is almost certainly not due to a GPS week
-	     * rollover, because that would throw the ZDA report backward
-	     * into the last rollover period instead of forward.  Almost
-	     * certainly it means that a century mark has passed while
-	     * gpsd was running, and we should trust the new ZDA year.
-	     */
-	    gpsd_report(LOG_WARN, "century rollover detected.\n");
-	    session->context->century = century;
-#if 0
-	} else if (century < session->context->century) {
-	    /*
-	     * This looks like a GPS week-counter rollover.  Hidden
-	     * assumption in the above test is that a bogus (small positive 
-	     * or negative) system clock value will always fail the
-	     * above guard and thus never trigger this error message.
-	     */
-	    gpsd_report(LOG_ERROR, "ZDA year %s less than clock year, "  
-			"probable GPS week rollover lossage\n", field[2]);
-#endif
 	} else {
-	    year -= 1900;	
-	    session->driver.nmea.date.tm_year = year;
+	    if (century > session->context->century) {
+		/*
+		 * This mismatch is almost certainly not due to a GPS week
+		 * rollover, because that would throw the ZDA report backward
+		 * into the last rollover period instead of forward.  Almost
+		 * certainly it means that a century mark has passed while
+		 * gpsd was running, and we should trust the new ZDA year.
+		 */
+		gpsd_report(LOG_WARN, "century rollover detected.\n");
+		session->context->century = century;
+	    } else if (century < session->context->century) {
+		/*
+		 * This looks like a GPS week-counter rollover.  Hidden
+		 * assumption in the above test is that a bogus (small positive 
+		 * or negative) system clock value will always fail the
+		 * above guard and thus never trigger this error message.
+		 */
+		gpsd_report(LOG_WARN, "ZDA year %d less than clock year, "  
+			    "probable GPS week rollover lossage\n", year);
+	    }
+	    session->driver.nmea.date.tm_year = year- 1900;
 	    session->driver.nmea.date.tm_mon = mon - 1;
 	    session->driver.nmea.date.tm_mday = mday;
 	    mask = TIME_IS;