MinumelArmMCU/UartHandler.hpp

#pragma once
#include <Arduino.h>

// Will parse serial messages using the serial interface supplied by the dev board
// Expects packets must be 5 bytes.
// Singleton-class
class UartHandler
{
    public:
        static UartHandler& getInstance() noexcept;

        // Will attempt to initialize the serial port, returns status.
        // May block up to 1000ms.
        bool init(const uint32_t baudRate);

        void close();

        void poll() noexcept;
        // Will write the next available whole line into char* (provide at least 16 bytes!)
        // Returns whether any data was written.
        // If data available is longer than 16 bytes, an error will be raised.
        bool getNextPacket(char* dest) noexcept;

        size_t send(const char* buf, size_t nbytes);
        size_t send(const String& str);

        // Returns how many packets are ready for reading
        uint8_t getNumAvailablePackets() const noexcept;

        bool isOpen() const noexcept;

        static constexpr uint8_t PACKET_SIZE = 5;
        static constexpr uint8_t PACKET_RINGBUF_SIZE = 16;

    private:
        // Will move the current contents of inBuf into packetRingBuf. Does NOT reset inBufPos!
        void pushPacket();

        UartHandler() noexcept;
        UartHandler(const UartHandler&) = delete;
        UartHandler(UartHandler&&) = delete;
        ~UartHandler();

        // By spec, packets will not exceed 16 bytes
        uint8_t inBuf[PACKET_SIZE];
        uint8_t inBufPos = 0;
        uint8_t packetRingBuf[PACKET_RINGBUF_SIZE * PACKET_SIZE];
        uint8_t packetRingBufReadPos = 0;   // 0 to PACKET_RINGBUF_SIZE
        uint8_t packetRingBufWritePos = 0;  // 0 to PACKET_RINGBUF_SIZE
        uint8_t numPacketsAvailable = 0;
};