Python中如何将十六进制字节数据打包为ctypes.Structure结构体实例

from ctypes import Structure, c_uint8, sizeof

class TestInfo(Structure):
    # 关闭字节对齐，保证结构内存布局和字段定义顺序完全一致
    _pack_ = 1
    _fields_ = [
        ('version', c_uint8),
        ('lsbyte', c_uint8),
        ('msbyte', c_uint8),
        ('free_space', c_uint8 * 2),
        ('recent_addtime', c_uint8 * 4),
        ('recent_erasetime', c_uint8 * 4),
        ('operation_support', c_uint8)
    ]

def uint8_arr_to_int(arr, byteorder='big'):
    """将ctypes的c_uint8数组转换为整数"""
    return int.from_bytes(bytes(arr), byteorder=byteorder)

# 原始十六进制数据处理
test_data = '51 af 01 00 65 f1 52 ff 60 f4 00 c7 60 0a'
# 转换为字节序列
data_bytes = bytes([int(x, 16) for x in test_data.split()])

# 校验数据长度是否和结构体大小匹配
assert len(data_bytes) == sizeof(TestInfo), "数据长度和结构体大小不匹配"

# 直接填充结构体
test_info = TestInfo.from_buffer_copy(data_bytes)

# 打印验证结果
print(f"TestInfo.version = 0x{test_info.version:02x}")
print(f"TestInfo.lsbyte  = 0x{test_info.lsbyte:02x}")
print(f"TestInfo.msbyte  = 0x{test_info.msbyte:02x}")
print(f"TestInfo.free_space = 0x{uint8_arr_to_int(test_info.free_space):04x}")
print(f"TestInfo.recent_addtime = 0x{uint8_arr_to_int(test_info.recent_addtime):08x}")
print(f"TestInfo.recent_erasetime = 0x{uint8_arr_to_int(test_info.recent_erasetime):08x}")
print(f"TestInfo.operation_support = 0x{test_info.operation_support:02x}")

运行输出 #

TestInfo.version = 0x51
TestInfo.lsbyte  = 0xaf
TestInfo.msbyte  = 0x01
TestInfo.free_space = 0x0065
TestInfo.recent_addtime = 0xf152ff60
TestInfo.recent_erasetime = 0xf400c760
TestInfo.operation_support = 0x0a

注意事项 #

• _pack_ = 1是必须配置的参数，否则ctypes会按照默认规则对结构体做字节对齐，导致结构内存大小大于14字节，数据填充错位
• 如果业务场景中多字节数组是小端序，只需要把uint8_arr_to_int函数的byteorder参数改为'little'即可
• from_buffer_copy是ctypes结构原生提供的内存复制方法，不需要手动逐个字段赋值，代码更简洁也不容易出错

内容的提问来源于stack exchange，提问作者TheDude