Implement Serial Json Read tuple

m-serial-json.h

@@ -199,8 +199,31 @@ m_serial_json_read_tuple_id(m_serial_read_t serial, const char *const field_name
   FILE *f = (FILE*) serial->data[0];
   int c = m_serial_json_read_skip(f);
   if (c == '}') return M_SERIAL_OK_DONE;
+  if (c == ',') {
+     // If first call of read_tuple_id, it is a failure
+     if (*id == -1) return M_SERIAL_FAIL;
+     c = m_serial_json_read_skip(f);
+  }
   if (c != '"') return M_SERIAL_FAIL;
-  
+  /* Read the field in the JSON */
+  char field[M_MAX_IDENTIFIER_LENGTH];
+  int n = 0;
+  do {
+     c =fgetc(f);
+     field[n++] = c;
+  } while (n < M_MAX_IDENTIFIER_LENGTH && c != EOF && c != '\"');
+  field[--n] = 0;
+  if (c != '"') return M_SERIAL_FAIL;
+  c =fgetc(f);
+  if (c != ':') return M_SERIAL_FAIL;
+  /* Search for field in field_name */
+  for(n = 0; n < max; n++) {
+     if (strcmp(field, field_name[n]) == 0)
+         break;
+  }
+  if (n == max) return M_SERIAL_FAIL;
+  *id = n;
+  return M_SERIAL_OK_CONTINUE;
 }
 
 static inline  m_serial_return_code_t m_serial_json_read_variant_start(m_serial_read_t serial, const char *const field_name[], const int max, int*id){ return M_SERIAL_FAIL; }