在 Python 中使用 8 位无符号算术校验和

Question

我有很多时间试图为我的串行数据导出校验和。我以字节形式接收数据，删除了标志和转义字符，将其放入列表中。说明文档用图形指定校验和位于数据结构的末尾。校验和是通过使用 8 位无符号算法对 Record 中的所有字节求和来计算的。不幸的是，我有一个巨大的数据文件：

[198, 2, 180, 4, 0, 0, 224, 253, 156, 94, 0, 0, 0, 0, 0, 0, 0, 0, 1, 22, 1, 1, 44, 2, 4, 189, 189, 255, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 224, 253, 156, 94, 51, 58, 0, 0, 0, 18, 2, 128, 10, 129, 1, 128, 1, 128, 1, 128, 1, 0, 0, 0, 1, 0, 2, 128, 2, 128, 2, 128, 1, 128, 1, 0, 0, 0, 2, 0, 2, 128, 2, 128, 2, 128, 1, 128, 0, 0, 0, 0, 11, 0, 1, 128, 1, 128, 1, 128, 1, 128, 0, 0, 0, 0, 3, 0, 1, 128, 1, 128, 1, 128, 1, 128, 3, 0, 0, 0, 3, 1, 1, 128, 1, 128, 1, 128, 1, 128, 3, 0, 0, 0, 11, 0, 4, 128, 3, 0, 0, 0, 12, 0, 4, 128, 0, 0, 0, 0, 13, 0, 1, 128, 0, 0, 0, 0, 14, 0, 1, 128, 3, 0, 0, 0, 0, 0, 1, 128, 2, 128, 2, 128, 1, 128, 7, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 203, 29, 3, 0, 0, 0, 0, 0, 38, 8, 38, 8, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 1, 0, 1, 128, 1, 128, 1, 128, 1, 128, 1, 128, 1, 128, 1, 128, 1, 128, 0, 0, 0, 0, 11, 0, 1, 128, 1, 128, 1, 128, 1, 128, 32, 0, 0, 0, 0, 0, 1, 128, 1, 128, 255, 141, 2, 128, 1, 128, 1, 128, 0, 0, 0, 0, 173, 1, 1, 128, 0, 0, 0, 0, 13, 0, 1, 128, 1, 128, 1, 128, 1, 128, 0, 0, 0, 0, 14, 0, 1, 128, 1, 128, 1, 128, 1, 128, 0, 0, 0, 0, 65, 0, 224, 253, 156, 94, 0, 0, 0, 0, 18, 2, 1, 128, 1, 128, 1, 128, 1, 128, 3, 0, 0, 0, 0, 0, 1, 128, 1, 128, 4, 128, 1, 128, 1, 128, 1, 128, 73, 13, 0, 0, 176, 192, 0, 0, 226, 1, 0, 0, 198, 2, 0, 0, 240, 127, 170, 1, 0, 0, 0, 0, 9, 49, 28, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 65, 3, 0, 0, 0, 0, 0, 0, 0, 0, 195, 165, 0, 0, 195, 165, 1, 128, 72, 8, 160, 15, 32, 78, 208, 7, 208, 7, 112, 23, 80, 5, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 4, 0, 0, 0, 4, 0, 0, 0, 2, 0, 0, 0, 1, 0, 0, 0, 0, 0, 52, 8, 0, 0, 0, 0, 208, 7, 112, 23, 17, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 178]

最后一个十六进制数是 178 (0xB2)，我假设它是校验和。当我应用校验和代码时，我在网上发现它很简单地将所有整数相加，远远超过“178”。谁能指出我正确的方向？谢谢

Answer 1

你可以使用：

l = [198, 2, 180, 4, 0, 0, 224, 253, 156, 94, 0, 0, 0, 0, 0, 0, 0, 0, 1, 22, 1, 1, 44, 2, 4, 189, 189, 255, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 224, 253, 156, 94, 51, 58, 0, 0, 0, 18, 2, 128, 10, 129, 1, 128, 1, 128, 1, 128, 1, 0, 0, 0, 1, 0, 2, 128, 2, 128, 2, 128, 1, 128, 1, 0, 0, 0, 2, 0, 2, 128, 2, 128, 2, 128, 1, 128, 0, 0, 0, 0, 11, 0, 1, 128, 1, 128, 1, 128, 1, 128, 0, 0, 0, 0, 3, 0, 1, 128, 1, 128, 1, 128, 1, 128, 3, 0, 0, 0, 3, 1, 1, 128, 1, 128, 1, 128, 1, 128, 3, 0, 0, 0, 11, 0, 4, 128, 3, 0, 0, 0, 12, 0, 4, 128, 0, 0, 0, 0, 13, 0, 1, 128, 0, 0, 0, 0, 14, 0, 1, 128, 3, 0, 0, 0, 0, 0, 1, 128, 2, 128, 2, 128, 1, 128, 7, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 203, 29, 3, 0, 0, 0, 0, 0, 38, 8, 38, 8, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 1, 0, 1, 128, 1, 128, 1, 128, 1, 128, 1, 128, 1, 128, 1, 128, 1, 128, 0, 0, 0, 0, 11, 0, 1, 128, 1, 128, 1, 128, 1, 128, 32, 0, 0, 0, 0, 0, 1, 128, 1, 128, 255, 141, 2, 128, 1, 128, 1, 128, 0, 0, 0, 0, 173, 1, 1, 128, 0, 0, 0, 0, 13, 0, 1, 128, 1, 128, 1, 128, 1, 128, 0, 0, 0, 0, 14, 0, 1, 128, 1, 128, 1, 128, 1, 128, 0, 0, 0, 0, 65, 0, 224, 253, 156, 94, 0, 0, 0, 0, 18, 2, 1, 128, 1, 128, 1, 128, 1, 128, 3, 0, 0, 0, 0, 0, 1, 128, 1, 128, 4, 128, 1, 128, 1, 128, 1, 128, 73, 13, 0, 0, 176, 192, 0, 0, 226, 1, 0, 0, 198, 2, 0, 0, 240, 127, 170, 1, 0, 0, 0, 0, 9, 49, 28, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 65, 3, 0, 0, 0, 0, 0, 0, 0, 0, 195, 165, 0, 0, 195, 165, 1, 128, 72, 8, 160, 15, 32, 78, 208, 7, 208, 7, 112, 23, 80, 5, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 4, 0, 0, 0, 4, 0, 0, 0, 2, 0, 0, 0, 1, 0, 0, 0, 0, 0, 52, 8, 0, 0, 0, 0, 208, 7, 112, 23, 17, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 178]

sum(l[:-1]) & 255

输出：

178

二进制和中发生 8 位溢出，因此您只保留和的最后 8 位