fix parser when no fix

RMC and GGA sentences were no properly parsed when there was no fix.
They were assuming numeric values between commas, but you just get a
string of commas when there’s no fix. This was causing the RMC ate to
be parsed incorrectly.

Adafruit_GPS.cpp

@@ -47,6 +47,8 @@ boolean Adafruit_GPS::parse(char *nmea) {
       //return false;
     }
   }
+  int32_t degree;
+  long minutes;
   char degreebuff[10];
   // look for a few common sentences
   if (strstr(nmea, "$GPGGA")) {
@@ -64,26 +66,34 @@ boolean Adafruit_GPS::parse(char *nmea) {
 
     // parse out latitude
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       strncpy(degreebuff, p, 2);
       p += 2;
       degreebuff[2] = '\0';
-    int32_t degree = atol(degreebuff) * 10000000;
+      degree = atol(degreebuff) * 10000000;
       strncpy(degreebuff, p, 2); // minutes
       p += 3; // skip decimal point
       strncpy(degreebuff + 2, p, 4);
       degreebuff[6] = '\0';
-    long minutes = 50 * atol(degreebuff) / 3;
+      minutes = 50 * atol(degreebuff) / 3;
       latitude_fixed = degree + minutes;
       latitude = degree / 100000 + minutes * 0.000006F;
+    }
     
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       if (p[0] == 'N') lat = 'N';
       else if (p[0] == 'S') lat = 'S';
       else if (p[0] == ',') lat = 0;
       else return false;
+    }
     
     // parse out longitude
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       strncpy(degreebuff, p, 3);
       p += 3;
       degreebuff[3] = '\0';
@@ -95,27 +105,47 @@ boolean Adafruit_GPS::parse(char *nmea) {
       minutes = 50 * atol(degreebuff) / 3;
       longitude_fixed = degree + minutes;
       longitude = degree / 100000 + minutes * 0.000006F;
+    }
     
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       if (p[0] == 'W') lon = 'W';
       else if (p[0] == 'E') lon = 'E';
       else if (p[0] == ',') lon = 0;
       else return false;
+    }
     
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       fixquality = atoi(p);
+    }
     
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       satellites = atoi(p);
+    }
     
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       HDOP = atof(p);
+    }
     
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       altitude = atof(p);
+    }
+    
     p = strchr(p, ',')+1;
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       geoidheight = atof(p);
+    }
     return true;
   }
   if (strstr(nmea, "$GPRMC")) {
@@ -143,6 +173,8 @@ boolean Adafruit_GPS::parse(char *nmea) {
 
     // parse out latitude
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       strncpy(degreebuff, p, 2);
       p += 2;
       degreebuff[2] = '\0';
@@ -154,15 +186,21 @@ boolean Adafruit_GPS::parse(char *nmea) {
       long minutes = 50 * atol(degreebuff) / 3;
       latitude_fixed = degree + minutes;
       latitude = degree / 100000 + minutes * 0.000006F;
+    }
     
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       if (p[0] == 'N') lat = 'N';
       else if (p[0] == 'S') lat = 'S';
       else if (p[0] == ',') lat = 0;
       else return false;
+    }
     
     // parse out longitude
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       strncpy(degreebuff, p, 3);
       p += 3;
       degreebuff[3] = '\0';
@@ -174,27 +212,38 @@ boolean Adafruit_GPS::parse(char *nmea) {
       minutes = 50 * atol(degreebuff) / 3;
       longitude_fixed = degree + minutes;
       longitude = degree / 100000 + minutes * 0.000006F;
+    }
     
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       if (p[0] == 'W') lon = 'W';
       else if (p[0] == 'E') lon = 'E';
       else if (p[0] == ',') lon = 0;
       else return false;
-
+    }
     // speed
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       speed = atof(p);
+    }
     
     // angle
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       angle = atof(p);
+    }
     
     p = strchr(p, ',')+1;
+    if (',' != *p)
+    {
       uint32_t fulldate = atof(p);
       day = fulldate / 10000;
       month = (fulldate % 10000) / 100;
       year = (fulldate % 100);
-
+    }
     // we dont parse the remaining, yet!
     return true;
   }