add arduino json lib

#182

lib/ArduinoJson/src/ArduinoJson/Polyfills/parseInteger.hpp

@@ -0,0 +1,41 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2018
+// MIT License
+
+#pragma once
+
+#include <stdlib.h>
+
+#include "../Configuration.hpp"
+#include "./ctype.hpp"
+
+namespace ArduinoJson {
+namespace Internals {
+template <typename T>
+T parseInteger(const char *s) {
+  if (!s) return 0;  // NULL
+
+  if (*s == 't') return 1;  // "true"
+
+  T result = 0;
+  bool negative_result = false;
+
+  switch (*s) {
+    case '-':
+      negative_result = true;
+      s++;
+      break;
+    case '+':
+      s++;
+      break;
+  }
+
+  while (isdigit(*s)) {
+    result = T(result * 10 + T(*s - '0'));
+    s++;
+  }
+
+  return negative_result ? T(~result + 1) : result;
+}
+}
+}