Add internal protocol decoding reset

src/modules/protocol.cpp

@@ -76,10 +76,12 @@ DecodeStatus Protocol::DecodeRequest(uint8_t c) {
 }
 
 uint8_t Protocol::EncodeRequest(const RequestMsg &msg, uint8_t *txbuff) {
+    constexpr uint8_t reqSize = 3;
     txbuff[0] = (uint8_t)msg.code;
     txbuff[1] = msg.value + '0';
     txbuff[2] = '\n';
-    return 3;
+    return reqSize;
+    static_assert(reqSize <= MaxRequestSize(), "Request message length exceeded the maximum size, increase the magic constant in MaxRequestSize()");
 }
 
 DecodeStatus Protocol::DecodeResponse(uint8_t c) {

src/modules/protocol.h

@@ -96,6 +96,10 @@ public:
     /// @returns number of bytes written into txbuff
     static uint8_t EncodeRequest(const RequestMsg &msg, uint8_t *txbuff);
 
+    /// @returns the maximum byte length necessary to encode a request message
+    /// Beneficial in case of pre-allocating a buffer for enconding a RequestMsg.
+    static constexpr uint8_t MaxRequestSize() { return 3; }
+
     /// Encode generic response Command Accepted or Rejected
     /// @param msg source request message for this response
     /// @param ar code of response parameter
@@ -131,6 +135,16 @@ public:
     /// @returns the most recently lexed response message
     inline const ResponseMsg GetResponseMsg() const { return responseMsg; }
 
+    /// resets the internal request decoding state (typically after an error)
+    void ResetRequestDecoder() {
+        rqState = RequestStates::Code;
+    }
+
+    /// resets the internal response decoding state (typically after an error)
+    void ResetResponseDecoder() {
+        rspState = ResponseStates::RequestCode;
+    }
+
 private:
     enum class RequestStates : uint8_t {
         Code, ///< starting state - expects message code