From John Hay:

  added code to verify the checksum and discard the line if it doesn't match
  discard the line if the position fix wasn't valid.
  extract date from gprmc if available.

diff --git a/gpsbabel/nmea.c b/gpsbabel/nmea.c
index a8c592bfddbae2970bebaa9ec567beeff23e48e5..c70b6863bb905ecb09a715ab377ce7ec8d972a13 100644 (file)
--- a/gpsbabel/nmea.c
+++ b/gpsbabel/nmea.c
@@ -153,8 +153,6 @@ gpgll_parse(char *ibuf)
                track_add_head(trk_head);
        }
 
-       waypt = waypt_new();
-
        memset(&tm, 0, sizeof(tm));
 
        sscanf(ibuf,"$GPGLL,%lf,%c,%lf,%c,%d,%c,",
@@ -162,12 +160,16 @@ gpgll_parse(char *ibuf)
                &lngdeg,&lngdir,
                &hms,&valid);
 
+       if (valid != 'A')
+               return;
        tm.tm_sec = hms % 100;
        hms = hms / 100;
        tm.tm_min = hms % 100;
        hms = hms / 100;
        tm.tm_hour = hms % 100;
 
+       waypt = waypt_new();
+
        waypt->creation_time = creation_time;
 
        if (latdir == 'S') latdeg = -latdeg;
@@ -198,21 +200,24 @@ gpgga_parse(char *ibuf)
                track_add_head(trk_head);
        }
 
-       waypt  = waypt_new();
-
        memset(&tm, 0, sizeof(tm));
 
-       sscanf(ibuf,"$GPGGA,%f,%lf,%c,%lf,%c,%d,%d,%lf,%lf,%c",
+       sscanf(ibuf,"$GPGGA,%lf,%lf,%c,%lf,%c,%d,%d,%lf,%lf,%c",
                &hms, &latdeg,&latdir,
                &lngdeg,&lngdir,
                &fix,&nsats,&hdop,&alt,&altunits);
 
+       if (fix == 0)
+               return;
+
        tm.tm_sec = (long) hms % 100;
        hms = hms / 100;
        tm.tm_min = (long) hms % 100;
        hms = hms / 100;
        tm.tm_hour = (long) hms % 100;
 
+       waypt  = waypt_new();
+
        waypt->creation_time = creation_time;
 
        if (latdir == 'S') latdeg = -latdeg;
@@ -234,6 +239,7 @@ gprmc_parse(char *ibuf)
        double hms;
        double speed, course;
        char fix;
+       unsigned int dmy;
        struct tm tm;
        waypoint *waypt;
 
@@ -242,22 +248,33 @@ gprmc_parse(char *ibuf)
                track_add_head(trk_head);
        }
 
-       waypt  = waypt_new();
-
        memset(&tm, 0, sizeof(tm));
 
-       sscanf(ibuf,"$GPRMC,%f,%c,%lf,%c,%lf,%c,%lf,%lf",
+       sscanf(ibuf,"$GPRMC,%lf,%c,%lf,%c,%lf,%c,%lf,%lf,%u",
                &hms, &fix, &latdeg, &latdir,
                &lngdeg, &lngdir,
-               &speed, &course);
+               &speed, &course, &dmy);
 
+       if (fix != 'A')
+               return;
        tm.tm_sec = (long) hms % 100;
        hms = hms / 100;
        tm.tm_min = (long) hms % 100;
        hms = hms / 100;
        tm.tm_hour = (long) hms % 100;
 
-       waypt->creation_time = mktime(&tm) + get_tz_offset() + current_time();
+       tm.tm_year = dmy % 100 + 100;
+       dmy = dmy / 100;
+       tm.tm_mon  = dmy % 100 - 1;
+       dmy = dmy / 100;
+       tm.tm_mday = dmy;
+       creation_time = mktime(&tm) + get_tz_offset();
+
+       if (posn_type == gpgga)
+               return;
+
+       waypt  = waypt_new();
+       waypt->creation_time = creation_time;
 
        if (latdir == 'S') latdeg = -latdeg;
        waypt->latitude = ddmm2degrees(latdeg);
@@ -310,18 +327,35 @@ gpzda_parse(char *ibuf)
        tm.tm_mday = dd;
        tm.tm_mon  = mm - 1;
        tm.tm_year = yy - 1900;
-       creation_time = mktime(&tm) - get_tz_offset();
+       creation_time = mktime(&tm) + get_tz_offset();
 }
 
 static void
 nmea_read(void)
 {
        char ibuf[1024];
+       char *ck;
+       int ckval, ckcmp;
        struct tm tm;
 
        creation_time = mktime(&tm) + get_tz_offset() + current_time();
 
        while (fgets(ibuf, sizeof(ibuf), file_in)) {
+               ck = rindex(ibuf, '*');
+               if (ck != NULL) {
+                       *ck = '\0';
+                       ckval = nmea_cksum(&ibuf[1]);
+                       *ck = '*';
+                       ck++;
+                       sscanf(ck, "%2X", &ckcmp);
+                       if (ckval != ckcmp) {
+#if 0
+                               printf("ckval %X, %X, %s\n", ckval, ckcmp, ck);
+                               printf("NMEA %s\n", ibuf);
+#endif
+                               continue;
+                       }
+               }
                if (0 == strncmp(ibuf, "$GPWPL,", 7)) {
                        gpwpl_parse(ibuf);
                } else
@@ -331,9 +365,13 @@ nmea_read(void)
                } else
                if (0 == strncmp(ibuf, "$GPRMC,", 7)) {
                        if (posn_type != gpgga) {
-                       posn_type = gprmc;
-                               gprmc_parse(ibuf);
+                               posn_type = gprmc;
                        }                       
+                       /*                      
+                        * Allways call gprmc_parse() because like GPZDA
+                        * it contains the full date.
+                        */                     
+                       gprmc_parse(ibuf);
                } else
                if (0 == strncmp(ibuf, "$GPGLL,", 7)) {
                        if ((posn_type != gpgga) && (posn_type != gprmc)) {