Merge pull request #169 from ladyada-eagleclaw/fix-rmb-partial-update

Preserve waypoint data when RMB parsing fails

extras/tests/rmb_state/rmb_state.ino

@@ -0,0 +1,49 @@
+#include <Adafruit_GPS.h>
+
+Adafruit_GPS GPS;
+bool testsPassed = false;
+
+void setup() {
+  Serial.begin(115200);
+  // Wait briefly for the Serial Monitor on native USB boards.
+  while (!Serial && millis() < 5000) {
+    delay(10);
+  }
+  delay(250);
+  Serial.println("Adafruit GPS RMB state regression");
+
+  char good[] = "$GPRMB,A,0.10,R,DEST,START,4807.038,N,01131.000,E,1.0,84.4,2.5,A*44";
+  if (!GPS.parse(good)) {
+    Serial.println("FAIL: valid RMB sentence was rejected");
+    return;
+  }
+  Serial.println("PASS: valid RMB sentence was accepted");
+  nmea_float_t crossTrackError = GPS.get(NMEA_XTE);
+  nmea_float_t latitude = GPS.get(NMEA_LATWP);
+  nmea_float_t longitude = GPS.get(NMEA_LONWP);
+
+  // The checksum is valid, but Q is not a longitude direction.
+  char bad[] = "$GPRMB,A,0.20,L,OTHER,NEW,4907.038,N,01231.000,Q,2.0,90.0,3.0,A*17";
+  if (GPS.parse(bad)) {
+    Serial.println("FAIL: invalid RMB sentence was accepted");
+    return;
+  }
+  Serial.println("PASS: invalid RMB sentence was rejected");
+  if (GPS.get(NMEA_XTE) != crossTrackError ||
+      GPS.get(NMEA_LATWP) != latitude || GPS.get(NMEA_LONWP) != longitude ||
+      strcmp(GPS.toID, "DEST") || strcmp(GPS.fromID, "START")) {
+    Serial.println("FAIL: rejected sentence changed the waypoint data");
+    return;
+  }
+  Serial.println("PASS: previous waypoint data was preserved");
+  testsPassed = true;
+}
+
+void loop() {
+  if (testsPassed) {
+    Serial.println("PASS: RMB state regression");
+  } else {
+    Serial.println("FAIL: RMB state regression");
+  }
+  delay(2000);
+}

src/NMEA_parse.cpp

@@ -378,16 +378,9 @@ bool Adafruit_GPS::parse(char *nmea) {
     if (!isEmpty(p))
       xteDir = *p;
     p = strchr(p, ',') + 1;
-    if (xte < 10000.0f && xteDir != 'X') {
-      if (xteDir == 'L')
-        xte *= -1.0f;
-      newDataValue(NMEA_XTE, xte);
-    }
-    if (!isEmpty(p))
-      parseStr(toID, p, NMEA_MAX_WP_ID);
+    char *toIDField = p;
     p = strchr(p, ',') + 1;
-    if (!isEmpty(p))
-      parseStr(fromID, p, NMEA_MAX_WP_ID);
+    char *fromIDField = p;
     p = strchr(p, ',') + 1;
     nmea_float_t latitudeWP = 0;
     nmea_float_t longitudeWP = 0;
@@ -404,8 +397,6 @@ bool Adafruit_GPS::parse(char *nmea) {
       if (!parseCoord(p, &latitudeDegreesWP, &latitudeWP, &latitude_fixedWP,
                       &latWP))
         return false;
-      else
-        newDataValue(NMEA_LATWP, latitudeDegreesWP);
     }
     p = strchr(p, ',') + 1;
     p = strchr(p, ',') + 1;
@@ -415,9 +406,24 @@ bool Adafruit_GPS::parse(char *nmea) {
       if (!parseCoord(p, &longitudeDegreesWP, &longitudeWP, &longitude_fixedWP,
                       &lonWP))
         return false;
-      else
-        newDataValue(NMEA_LONWP, longitudeDegreesWP);
     }
+
+    // Any supplied coordinates passed validation. Save the cross-track error,
+    // waypoint IDs, and coordinates now; a rejected sentence must leave the
+    // previous data and history intact.
+    if (xte < 10000.0f && xteDir != 'X') {
+      if (xteDir == 'L')
+        xte *= -1.0f;
+      newDataValue(NMEA_XTE, xte);
+    }
+    if (!isEmpty(toIDField))
+      parseStr(toID, toIDField, NMEA_MAX_WP_ID);
+    if (!isEmpty(fromIDField))
+      parseStr(fromID, fromIDField, NMEA_MAX_WP_ID);
+    if (latWP != 'X')
+      newDataValue(NMEA_LATWP, latitudeDegreesWP);
+    if (lonWP != 'X')
+      newDataValue(NMEA_LONWP, longitudeDegreesWP);
     p = strchr(p, ',') + 1;
     p = strchr(p, ',') + 1;
     if (!isEmpty(p))