added idf.py support

Fix compiler warnings

CMakeLists.txt

@@ -0,0 +1,5 @@
+idf_component_register(
+    SRC_DIRS "src"
+    INCLUDE_DIRS "." "src"
+    REQUIRES arduino-esp32
+)

src/Adafruit_GPS.cpp

@@ -352,7 +352,7 @@ char Adafruit_GPS::read(void) {
   // Serial.print(c);
 
   currentline[lineidx] = c;
-  lineidx++;
+  lineidx = lineidx + 1;
   if (lineidx >= MAXLINELENGTH)
     lineidx = MAXLINELENGTH -
               1; // ensure there is someplace to put the next received character

src/NMEA_build.cpp

@@ -565,7 +565,15 @@ char *Adafruit_GPS::build(char *nmea, const char *thisSource,
 
   addChecksum(nmea); // Successful completion
   if (!noCRLF) { // Add Carriage Return and Line Feed to comply with NMEA-183
-    sprintf(nmea, "%s\r\n", nmea);
+    size_t len = strlen(nmea);
+    char *nmeaWithCRLF =
+        (char *)malloc(len + 3); // +2 for \r\n, +1 for null terminator
+    if (nmeaWithCRLF) {
+      strcpy(nmeaWithCRLF, nmea);   // Copy original string
+      strcat(nmeaWithCRLF, "\r\n"); // Append \r\n
+      strcpy(nmea, nmeaWithCRLF);   // Copy back to original buffer
+      free(nmeaWithCRLF);           // Free the allocated memory
+    }
   }
   return nmea; // return pointer to finished product
 }
@@ -591,7 +599,8 @@ void Adafruit_GPS::addChecksum(char *buff) {
     i++;
   }
 
-  // Calculate the needed buffer size: original length + 3 (*XX) + 1 (null terminator)
+  // Calculate the needed buffer size: original length + 3 (*XX) + 1 (null
+  // terminator)
   int neededSize = strlen(buff) + 4;
   char *tempBuffer = (char *)malloc(neededSize);
 
@@ -600,7 +609,8 @@ void Adafruit_GPS::addChecksum(char *buff) {
     snprintf(tempBuffer, neededSize, "%s*%02X", buff, cs);
 
     // Copy the formatted string back to the original buffer
-    // Note: Make sure the original buffer is large enough to hold the new string.
+    // Note: Make sure the original buffer is large enough to hold the new
+    // string.
     strcpy(buff, tempBuffer);
 
     // Free the allocated memory to avoid memory leaks