69 lines
2.3 KiB
Python
69 lines
2.3 KiB
Python
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class crc16:
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"""
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CRC16校验函数
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"""
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@staticmethod
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def cal(data_bytes):
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"""
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计算CRC16校验值（不包含最后两个字节的CRC）
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参数:
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data_bytes: 要计算CRC16的字节数据，可以是bytes、bytearray或整数列表
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返回:
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int: 计算得到的CRC16校验值
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"""
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PRESET_VALUE = 0xFFFF
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POLYNOMIAL = 0x8408
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# 初始化CRC值
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crc_value = PRESET_VALUE
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length = len(data_bytes)
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# 处理每个字节
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for i in range(length):
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# 获取当前字节（确保是0-255范围内的整数）
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current_byte = data_bytes[i] & 0xFF
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# 与当前CRC值异或
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crc_value ^= current_byte
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# 处理每个位
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for j in range(8):
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# 检查最低位
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if crc_value & 0x0001:
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# 最低位为1，右移后与多项式异或
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crc_value = (crc_value >> 1) ^ POLYNOMIAL
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else:
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# 最低位为0，仅右移
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crc_value = crc_value >> 1
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# 确保crc_value是16位无符号整数
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crc_value &= 0xFFFF
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return crc_value
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@staticmethod
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def verify(data_bytes):
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"""
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验证数据后两位的CRC MSB和LSB是否正确
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参数:
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data_bytes: 要验证CRC16的字节数据，可以是bytes、bytearray或整数列表
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返回:
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bool: True表示CRC验证通过，False表示验证失败
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"""
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if len(data_bytes) < 2:
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raise ValueError("数据长度至少需要2字节以包含CRC校验值")
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# 提取数据部分（除去最后两个CRC字节）
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data_part = data_bytes[:-2]
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# 提取接收到的CRC值（LSB在前，MSB在后）
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received_crc_lsb = data_bytes[-2]
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received_crc_msb = data_bytes[-1]
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received_crc = (received_crc_msb << 8) | received_crc_lsb
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# 计算数据部分的CRC值
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calculated_crc = crc16.cal(data_part)
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# 比较计算得到的CRC值和接收到的CRC值
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return calculated_crc == received_crc
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