adding new function

pirds_library/PIRDS.cpp

@@ -266,3 +266,16 @@ Message get_message_from_JSON(char* buff,uint16_t blim) {
   assign_value_message(&m,k,v);
   return m;
 }
+
+char get_event_designation_char_from_json(char* buff,uint16_t blim) {
+    char *k = strtok(buff , "{,:}");
+    char *v = strtok(NULL, "{,:}");
+    char *stripped_key = trimwhitespace(k);
+    char *stripped_value = trimwhitespace(v);
+    if (0 == strcmp(stripped_key,"\"event\"")) {
+      return stripped_value[1];
+    } else {
+      return '\0'; // same as zero, an error condition
+    }
+
+}

pirds_library/PIRDS.h

@@ -90,6 +90,13 @@ typedef struct Message
 #define FLOW_TOO_LOW  "FLOW OUT OF RANGE LOW"
 #define SAVE_LOG_TO_FILE "SAVE_LOG_TO_FILE:"
 
+
+// This function returns the character in the "event" tag of the JSON object,
+// or null/0 if there is none. This function can be used to determine if
+// a JSON string is a measurement ('M') or a message ('E'). This then
+// allows the proper interpretation function below to be called.
+char get_event_designation_char_from_json(char* buff,uint16_t blim);
+
 /* Fill the byte buffer with a PIRDS-standard bytes from the
    Measurement Object */
 uint16_t fill_byte_buffer_measurement(Measurement* m,uint8_t* buff,uint16_t blim);

pirds_library/test_PIRDS.c.ext

@@ -108,12 +108,38 @@ static char *test_can_create_Message_and_read_back_as_JSON() {
 }
 
 
+static char *test_get_event_designation() {
+  Message me = {
+    'E','M',4000,18,"Buckminster Fuller"
+  };
+  Measurement ms = {
+    'M','T',101,'B',3,-10115
+  };
+
+  const uint16_t BUFF_SIZE = 256+7;
+  char buff[BUFF_SIZE];
+  int err;
+  err = fill_JSON_buffer_message(&me,buff,BUFF_SIZE);
+  mu_assert("buffer problem", err > 0);
+  mu_assert("failed to get Message as E", 'E' == get_event_designation_char_from_json(buff,BUFF_SIZE));
+
+  err = fill_JSON_buffer_measurement(&ms,buff,BUFF_SIZE);
+  mu_assert("failed to get Measurement as M", 'M' == get_event_designation_char_from_json(buff,BUFF_SIZE));
+
+  // NOTE: Intentionally misspelled!
+  sprintf(buff,"{ exent: X}");
+  mu_assert("failed to return null when no event",0 == get_event_designation_char_from_json(buff,BUFF_SIZE));
+
+  return 0;
+}
+
 static char * all_tests() {
   mu_run_test(test_can_create_Measurement_and_read_back_as_byte_buffer);
   mu_run_test(test_can_create_Measurement_and_read_back_as_JSON);
 
   mu_run_test(test_can_create_Message_and_read_back_as_byte_buffer);
   mu_run_test(test_can_create_Message_and_read_back_as_JSON);
+  mu_run_test(test_get_event_designation);
 
   return 0;
 }