cs_UartProtocol.h

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#pragma once
 
#include <protocol/cs_UartMsgTypes.h>
#include <protocol/cs_UartOpcodes.h>
 
#include <cstdint>
 
// bit:  7654 3210
#define UART_START_BYTE 0x7E        // "~"   0111 1110  resets the state
#define UART_ESCAPE_BYTE 0x5C       // "\"   0101 1100  next byte gets bits flipped that are in flip mask
#define UART_ESCAPE_FLIP_MASK 0x40  //       0100 0000
 
#define UART_PROTOCOL_MAJOR 1
#define UART_PROTOCOL_MINOR 0
 
#define UART_PROTOCOL_VALIDATION 0xCAFEBABE
 
enum class UartMsgType : uint8_t {
    UART_MSG           = 0,    // Payload is: uart_msg_header + data
    ENCRYPTED_UART_MSG = 128,  // Payload is: uart_encrypted_msg_header + encrypted blocks
};
 
struct __attribute__((__packed__)) uart_msg_size_header_t {
    uint16_t size = 0;  // Size of all remaining bytes, including tail.
};
 
struct __attribute__((__packed__)) uart_msg_wrapper_header_t {
    uint8_t protocolMajor = UART_PROTOCOL_MAJOR;
    uint8_t protocolMinor = UART_PROTOCOL_MINOR;
    uint8_t type          = 0;
    // Followed by payload
};
 
struct __attribute__((__packed__)) uart_encrypted_msg_header_t {
    uint8_t packetNonce[PACKET_NONCE_LENGTH];
    uint8_t keyId;
    // Followed by encrypted data
};
 
struct __attribute__((__packed__)) uart_encrypted_data_header_t {
    uint32_t validation;
    uint16_t size;  // Size of uart msg.
                    // Followed by uart msg and padding.
};
 
struct __attribute__((__packed__)) uart_msg_header_t {
    uint16_t type;  // Type of message, see ..
                    // Followed by data.
};
 
struct __attribute__((__packed__)) uart_msg_tail_t {
    uint16_t crc;  // The CRC16 (CRC-16-CCITT) of everything after the size field.
};
 
namespace UartProtocol {
void escape(uint8_t& val);
 
void unEscape(uint8_t& val);
 
uint16_t crc16(const uint8_t* data, uint16_t size);
 
void crc16(const uint8_t* data, const uint16_t size, uint16_t& crc);
};  // namespace UartProtocol