From: Dave Hart <hart@ntp.org>
Date: Mon, 1 Nov 2010 00:22:07 +0000 (+0000)
Subject: [Bug 1691] Use first NMEA sentence each second.
X-Git-Tag: NTP_4_2_6P3_RC9~9
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a7c148273a941d5b438acf7ce808494d1d407e16;p=thirdparty%2Fntp.git

[Bug 1691] Use first NMEA sentence each second.

bk: 4cce082fak9HYT0Jkzn9PZ5_hX4K7A
---

diff --git a/ntpd/refclock_nmea.c b/ntpd/refclock_nmea.c
index 5683629f7..22ec19d90 100644
--- a/ntpd/refclock_nmea.c
+++ b/ntpd/refclock_nmea.c
@@ -172,6 +172,7 @@ struct nmeaunit {
 	l_fp	tstamp;		/* timestamp of last poll */
 	int	gps_time;	/* 0 UTC, 1 GPS time */
 		/* per sentence checksum seen flag */
+	struct calendar used;	/* hh:mm:ss of used sentence */
 	u_char	cksum_seen[NMEA_ARRAY_SIZE];
 };
 
@@ -642,9 +643,14 @@ nmea_receive(
 	 * There is a case that a <CR><LF> gives back a "blank" line.
 	 * We can't have a well-formed sentence with less than 8 chars.
 	 */
-	if (rd_lencode < 8)
+	if (0 == rd_lencode)
 		return;
 
+	if (rd_lencode < 8) {
+		refclock_report(peer, CEVNT_BADREPLY);
+		return;
+	}
+
 	DPRINTF(1, ("nmea: gpsread %d %s\n", rd_lencode, rd_lastcode));
 
 	/*
@@ -732,14 +738,7 @@ nmea_receive(
 		return;
 	}
 
-	pp->lencode = (u_short)rd_lencode;
-	memcpy(pp->a_lastcode, rd_lastcode, pp->lencode + 1);
-	cp = pp->a_lastcode;
-
-	up->tstamp = rd_timestamp;
-	pp->lastrec = up->tstamp;
-
-	DPRINTF(1, ("nmea: timecode %d %s\n", pp->lencode, pp->a_lastcode));
+	cp = rd_lastcode;
 
 	/* Grab field depending on clock string type */
 	memset(&date, 0, sizeof(date));
@@ -856,6 +855,20 @@ nmea_receive(
 		return;
 	}
 
+	/*
+	 * Used only the first recognized sentence each second.
+	 */
+	if (date.hour   == up->used.hour   &&
+	    date.minute == up->used.minute &&
+	    date.second == up->used.second)
+		return;
+
+	pp->lencode = (u_short)rd_lencode;
+	memcpy(pp->a_lastcode, rd_lastcode, pp->lencode + 1);
+	up->tstamp = rd_timestamp;
+	pp->lastrec = up->tstamp;
+	DPRINTF(1, ("nmea: timecode %d %s\n", pp->lencode, pp->a_lastcode));
+
 	/*
 	 * Convert date and check values.
 	 */
@@ -886,6 +899,10 @@ nmea_receive(
 		return;
 	}
 
+	up->used.hour = date.hour;
+	up->used.minute = date.minute;
+	up->used.second = date.second;
+
 	/*
 	 * If "fudge 127.127.20.__ flag4 1" is configured in ntp.conf,
 	 * remove the location and checksum from the NMEA sentence