bci_algo/Device/protocol.py

from typing import List, Tuple, Union, Optional


class ProtocolFrame:
    # 协议常量
    FRAME_HEADER = 0xAA
    FRAME_TAIL1 = 0x55
    FRAME_TAIL2 = 0x55
    RESERVED_SIZE = 6
    MIN_FRAME_SIZE = 13  # 帧头1 + 功能1 + 长度2 + 预留6 + CRC1 + 包尾2
    MAX_DATA_LENGTH = 0xFFFF  # 最大数据长度 (2字节能表示的最大值)

    @staticmethod
    def calculate_crc8(data: bytes) -> bytes:
        """
        计算CRC8校验值
        Args:
            data: 需要计算CRC的数据
        Returns:
            一个字节的CRC值（bytes类型）
        """
        crc = 0
        for byte in data:
            crc ^= byte
            for _ in range(8):
                crc = ((crc << 1) ^ 0x07 if crc & 0x80 else crc << 1) & 0xFF
        return bytes([crc])

    @classmethod
    def pack(cls, function, data: Union[bytes, bytearray, List[int]],
             reserved: Optional[Union[bytes, bytearray, List[int]]] = None) -> bytes:
        """
        协议打包函数

        Args:
            function: 功能码 (1字节)
            data: 数据块
            reserved: 预留字节(6字节，可选)

        Returns:
            打包后的字节数据
        """
        # 检查功能码
        if function != None:
            if not 0 <= function <= 0xFF:
                raise ValueError("功能码必须是1字节")

        # 转换数据为bytearray
        if isinstance(data, list):
            data = bytearray(data)
        elif isinstance(data, bytes):
            data = bytearray(data)

        # 检查数据长度
        data_length = len(data)
        if data_length > cls.MAX_DATA_LENGTH:
            raise ValueError(f"数据长度超过最大值 {cls.MAX_DATA_LENGTH}")

        # 处理预留字节
        if reserved is None:
            reserved = bytearray([0] * cls.RESERVED_SIZE)
        else:
            if isinstance(reserved, list):
                reserved = bytearray(reserved)
            elif isinstance(reserved, bytes):
                reserved = bytearray(reserved)
            if len(reserved) != cls.RESERVED_SIZE:
                raise ValueError(f"预留字节必须是{cls.RESERVED_SIZE}字节")

        # 构建帧
        frame = bytearray([cls.FRAME_HEADER])  # 帧头 (1字节)
        if function != None:
            frame.append(function)  # 功能码 (1字节)
            data_length+=6

        # 数据长度 (2字节，大端序)
        frame.append((data_length >> 8) & 0xFF)  # 高字节
        frame.append(data_length & 0xFF)  # 低字节

        if function != None:
            frame.extend(reserved)  # 预留字节 (6字节)
        frame.extend(data)  # 数据块 (变长)

        # 计算CRC (从功能码开始到数据块结束)
        crc = cls.calculate_crc8(frame[1:])  # 不包含帧头
        frame.extend(crc)  # CRC校验 (1字节)

        # 添加帧尾
        frame.extend([cls.FRAME_TAIL1, cls.FRAME_TAIL2])  # 帧尾 (2字节)

        return bytes(frame)

    @classmethod
    def unpack(cls, data: Union[bytes, bytearray]) -> Tuple[int, bytearray, bytearray]:
        """
        协议解包函数

        Args:
            data: 待解析的字节数据

        Returns:
            (功能码, 数据块, 预留字节)

        Raises:
            ValueError: 当数据格式不正确时
        """
        # 检查数据长度
        if len(data) < cls.MIN_FRAME_SIZE:
            raise ValueError("数据长度不足")

        # 检查帧头
        if data[0] != cls.FRAME_HEADER:
            raise ValueError("帧头错误")

        # 检查帧尾
        if data[-2:] != bytes([cls.FRAME_TAIL1, cls.FRAME_TAIL2]):
            raise ValueError("帧尾错误")

        # 解析基本信息
        function = data[1]  # 功能码 (1字节)

        # 数据长度 (2字节，大端序)
        data_length = (data[2] << 8) | data[3]

        reserved = data[4:10]  # 预留字节 (6字节)

        # 检查数据长度
        expected_length = cls.MIN_FRAME_SIZE + data_length
        if len(data) != expected_length:
            raise ValueError(f"数据长度不匹配: 期望{expected_length}字节，实际{len(data)}字节")

        # 提取数据块
        payload = data[10:10 + data_length]

        # 验证CRC (从功能码开始到数据块结束)
        received_crc = data[-3]
        calculated_crc = cls.calculate_crc8(data[1:-3])[0]  # 获取字节值

        if received_crc != calculated_crc:
            raise ValueError(f"CRC校验失败: 期望{calculated_crc:02X}，实际{received_crc:02X}")

        return function, bytearray(payload), bytearray(reserved)



def print_hex(data: bytes, label: str = ""):
    """打印十六进制数据，并按字节添加空格"""
    hex_str = ' '.join([f"{b:02X}" for b in data])
    if label:
        print(f"{label}: {hex_str}")
    else:
        print(hex_str)


def print_frame_details(data: bytes):
    """打印帧的详细信息"""
    print("帧详细信息:")
    print(f"帧头: {data[0]:02X}")
    print(f"功能码: {data[1]:02X}")
    print(f"数据长度: {data[2]:02X} {data[3]:02X} ({(data[2] << 8) | data[3]}字节)")
    print(f"预留字节: {' '.join([f'{b:02X}' for b in data[4:10]])}")
    data_length = (data[2] << 8) | data[3]
    print(f"数据块: {' '.join([f'{b:02X}' for b in data[10:10 + data_length]])}")
    print(f"CRC校验: {data[-3]:02X}")
    print(f"帧尾: {data[-2]:02X} {data[-1]:02X}")


# 使用示例
def example_usage():
    try:


        # 示例1：简单数据打包
        function_code = 0x01
        data = [0x1]
        packed_data = ProtocolFrame.pack(function_code, data)
        print_hex(packed_data, "示例1 - 完整帧")
        print_frame_details(packed_data)
        print()

        # 示例3：解包验证
        function, payload, reserved = ProtocolFrame.unpack(packed_data)
        print("解包结果:")
        print(f"功能码: 0x{function:02X}")
        print_hex(payload, "数据块")
        print_hex(reserved, "预留字节")

    except ValueError as e:
        print(f"错误: {e}")


if __name__ == "__main__":
    example_usage()