{"id":215,"date":"2017-04-06T05:02:58","date_gmt":"2017-04-06T05:02:58","guid":{"rendered":""},"modified":"2017-04-06T05:02:58","modified_gmt":"2017-04-06T05:02:58","slug":"","status":"publish","type":"post","link":"http:\/\/weizn.net\/?p=215","title":{"rendered":"[\u8f6c]ctypes+struct\u5b9e\u73b0\u7c7bc\u7684\u7ed3\u6784\u5316\u6570\u636e\u4e32\u884c\u5904\u7406"},"content":{"rendered":"

\n\thttp:\/\/blog.csdn.net\/machael_sonic\/article\/details\/50266499<\/a><\/span>\n<\/p>\n

\n\t
\n<\/span>\n<\/p>\n

\n\t1. \u7528C\/C++\u5b9e\u73b0\u7684\u7ed3\u6784\u5316\u6570\u636e\u5904\u7406<\/span>\n<\/p>\n

\n\u5728\u6d89\u53ca\u5230\u6bd4\u8f83\u5e95\u5c42\u7684\u901a\u4fe1\u534f\u8bae\u5f00\u53d1\u8fc7\u7a0b\u4e2d, \u5f80\u5f80\u9700\u8981\u5f00\u53d1\u8bed\u8a00\u80fd\u591f\u6709\u6548\u7684\u8868\u8fbe\u548c\u5904\u7406\u6240\u5b9a\u4e49\u7684\u901a\u4fe1\u534f\u8bae\u7684\u6570\u636e\u7ed3\u6784. \u5728\u8fd9\u65b9\u9762\u662fC\/C++\u8bed\u8a00\u662f\u5177\u6709\u5929\u7136\u4f18\u52bf\u7684: \u901a\u8fc7struct, union, \u548cbit-fields, C\/C++\u80fd\u591f\u4ee5\u4e00\u79cd\u6700\u6709\u6548\u7387\u4e5f\u6700\u81ea\u7136\u7684\u65b9\u5f0f\u5904\u7406\u6b64\u7c7b\u95ee\u9898.<\/span><\/p>\n

\u4e3e\u4f8b\u8bf4\u660e\u4e00\u4e0b, \u4e0b\u56fe\u662f\u667a\u80fd\u7535\u7f51\u7528\u4e8e\u8fdc\u7a0b\u81ea\u52a8\u6284\u8868\u7684\u901a\u4fe1\u534f\u8bae\u7684\u4e00\u90e8\u5206 <\/span>
\n\"\u8fd9\u91cc\u5199\u56fe\u7247\u63cf\u8ff0\" <\/span>

\n\"\u8fd9\u91cc\u5199\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

\u7528C\u53ef\u4ee5\u63cf\u8ff0\u5982\u4e0b:<\/span><\/p>\n

  struct<\/span>
\n  {<\/span>
\n    unsigned char  uRouter:1;  \/\/\u8def\u7531\u6807\u8bc6<\/span>
\n    unsigned char   uSubNode:1;\/\/\u9644\u5c5e\u8282\u70b9\u6807\u8bc6<\/span>
\n    unsigned char   uCM:1;     \/\/\u901a\u4fe1\u6a21\u5757\u6807\u8bc6<\/span>
\n    unsigned char   uCD:1;     \/\/\u51b2\u7a81\u68c0\u6d4b<\/span>
\n    unsigned char   uLevel:4;  \/\/\u4e2d\u7ee7\u7ea7\u522b<\/span>
\n    unsigned char   uChannel:4;\/\/\u4fe1\u9053\u6807\u8bc6<\/span>
\n    unsigned char   uErrBate:4;\/\/\u7ea0\u9519\u7f16\u7801\u6807\u8bc6<\/span>
\n    unsigned char   uResBytes; \/\/\u9884\u8ba1\u5e94\u7b54\u5b57\u8282\u6570<\/span>
\n    unsigned short  uSpeed:15; \/\/\u901a\u4fe1\u6ce2\u7279\u7387,BIN\u683c\u5f0f<\/span>
\n    unsigned short  uUnit:1;   \/\/0:bps;1:kbps<\/span>
\n    unsigned char  uReserve;<\/span>
\n  } Req;<\/span><\/p>\n

\u8fd9\u6837\u4e0d\u4ec5\u6e05\u695a\u7684\u63cf\u8ff0\u4e86\u5b8c\u5168\u7b26\u5408\u901a\u4fe1\u534f\u8bae\u8981\u6c42\u7684\u62a5\u6587\u6570\u636e\u7ed3\u6784, \u800c\u4e14\u8fd8\u6709\u81f3\u5c11\u4ee5\u4e0b\u4e24\u4e2a\u4f18\u70b9: <\/span>
\n1. \u5bf9\u7ed3\u6784\u4e2d\u7684\u4efb\u610f\u53d8\u91cf\u53d6\u5740\u8d4b\u503c\u53d6\u503c\u6781\u5176\u65b9\u4fbf, \u5982<\/span><\/p>\n

    struct Req r;<\/span>
\n    r.uCD = 0;<\/span>
\n    r.uChannel = 0x0F;<\/span><\/p>\n

\u5e76\u4e0d\u5fc5\u8d39\u5fc3\u7684\u8ba1\u7b97\u504f\u79fb\u91cf. \u800c\u4e14\u5982\u679c\u4ee5\u540e\u901a\u4fe1\u534f\u8bae\u5347\u7ea7\u4e86, \u53ea\u9700\u8981\u5c06\u6570\u636e\u7ed3\u6784\u5b9a\u4e49\u66f4\u6539\u5373\u53ef, \u5176\u4f59\u4ee3\u7801\u5b8c\u5168\u4e0d\u7528\u53d8\u52a8. <\/span>
\n2. \u66f4\u91cd\u8981\u7684\u662f, \u8fd9\u4e2a\u6570\u636e\u7ed3\u6784\u5728\u8ba1\u7b97\u673a\u5185\u5b58\u4e2d\u5929\u7136\u7684\u5c31\u662f\u6309\u7167\u901a\u4fe1\u534f\u8bae\u7684\u4e32\u884c\u7ed3\u6784\u6392\u5217\u7684(\u5047\u8bbe\u5927\u7aef\u5c0f\u7aef\u95ee\u9898\u5df2\u8bbe\u7f6e\u6b63\u786e), \u53ea\u9700\u8981<\/span><\/p>\n

    struct Req r;<\/span>
\n    …<\/span>
\n    send((unsigned char *)&r, sizeof(r));<\/span><\/p>\n

\u5c31\u53ef\u4ee5\u4ee5\u901a\u4fe1\u534f\u8bae\u5b8c\u5168\u4e00\u81f4\u7684\u683c\u5f0f\u5c06\u6570\u636e\u8f6c\u6362\u6210\u5b57\u8282\u6d41\u53d1\u9001\u51fa\u53bb\u4e86. \u800c\u63a5\u6536\u89e3\u6790\u4e5f\u540c\u6837\u65b9\u4fbf:<\/span><\/p>\n

    struct Req rs;<\/span>
\n    unsigned char rcv_buffer[100];<\/span>
\n    …<\/span>
\n    rcv(rcv_buffer sizeof(Req));<\/span>
\n    memcpy((unsigned char *)&rs, rcv_buffer, sizeof(r));<\/span><\/p>\n

2. \u7528Python\u5b9e\u73b0\u7684\u7ed3\u6784\u5316\u6570\u636e\u5904\u7406<\/span><\/p>\n

\u73b0\u5728\u95ee\u9898\u6765\u4e86: \u5982\u679c\u7528Python, \u8fd8\u80fd\u591f\u540c\u6837\u65b9\u4fbf\u7684\u5b9e\u73b0\u4e0a\u8ff0\u7684\u7ed3\u6784\u5316\u6570\u636e\u5904\u7406\u5417? \u4e5f\u5c31\u662f\u9700\u8981\u5b9e\u73b0\u4ee5\u4e0b\u529f\u80fd:<\/span><\/p>\n

\u80fd\u591f\u4ee5\u53d8\u91cf\u540d\u8bbf\u95ee\u6570\u636e\u6bb5, \u4e0d\u9700\u8981\u624b\u52a8\u8ba1\u7b97\u504f\u79fb\u91cf<\/span>
\n\u80fd\u591f\u5904\u7406bit\u7ea7\u7684\u6570\u636e\u6bb5<\/span>
\n\u80fd\u591f\u65b9\u4fbf\u7684\u5f62\u6210\u4e32\u884c\u5316\u901a\u4fe1\u5b57\u8282\u6d41, \u4e5f\u80fd\u65b9\u4fbf\u7684\u4ece\u63a5\u6536\u7684\u5b57\u8282\u6d41\u4e2d\u89e3\u6790\u6570\u636e;<\/span>
\n\u6709\u4eba\u53ef\u80fd\u89c9\u5f97\u8fd9\u4e0d\u662f\u95ee\u9898: \u7528python\u7684\u5b57\u5178\u4e0d\u662f\u4e5f\u80fd\u5b9e\u73b0\u5417? \u4ed4\u7ec6\u60f3\u4e00\u60f3, \u5b57\u5178\u53ea\u80fd\u591f\u63d0\u4f9b\u7b2c\u4e00\u79cd\u9700\u6c42, \u5373\u4ee5\u53d8\u91cf\u540d\u8bbf\u95ee\u6570\u636e\u6bb5. \u4f46python\u56e0\u4e3a\u662f\u9ad8\u7ea7\u8bed\u8a00, \u6574\u6570\u53ea\u63d0\u4f9bint\u4e00\u79cd\u6570\u636e\u7ed3\u6784, \u800c\u534f\u8bae\u4e2d\u5f88\u591a\u65f6\u5019\u6570\u636e\u6bb5\u662fbit\u7ea7\u7684, \u6216\u5355\u5b57\u8282, \u4e24\u5b57\u8282, \u4e09\u5b57\u8282\u7684. \u53ea\u7528python\u539f\u751f\u7684\u6570\u636e\u7ed3\u6784\u662f\u4e0d\u80fd\u76f4\u63a5\u8bbf\u95eebit\u7ea7\u7684\u6570\u636e\u6bb5\u7684, \u751a\u81f3\u8fde\u6570\u636e\u4f53\u6700\u540e\u5230\u5e95\u5360\u4e86\u51e0\u5b57\u8282, \u90fd\u4e0d\u80fd\u65b9\u4fbf\u7684\u7edf\u8ba1.<\/span><\/p>\n

\u4e3a\u4e86\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898, \u672c\u8d28\u8fd8\u662f\u8981\u9000\u56de\u5230C\u8bed\u8a00\u7684\u7ea7\u522b\u6765. \u597d\u5728python\u63d0\u4f9b\u4e86ctypes\u8fd9\u4e2a\u5e93, \u80fd\u591f\u8ba9\u6211\u4eec\u5728python\u4e2d\u5b9e\u73b0\u7c7b\u4f3cC\u8bed\u8a00\u7684\u529f\u80fd.<\/span><\/p>\n

>>> from ctypes import *<\/span>
\n>>> class Req(Structure):<\/span>
\n    _fields_=[(‘uRouter’,c_ubyte,1),<\/span>
\n            (‘uSubNode’,c_ubyte,1),<\/span>
\n            (‘uCM’,c_ubyte,1),<\/span>
\n            (‘uCD’,c_ubyte,1),<\/span>
\n            (‘uLevel’,c_ubyte,4),<\/span>
\n            (‘uChannel’,c_ubyte,4),<\/span>
\n            (‘uErrBate’,c_ubyte,4),<\/span>
\n            (‘uResBytes’,c_ubyte),<\/span>
\n            (‘uSpeed’,c_ushort,15),<\/span>
\n            (‘uUnit’,c_ushort,1),<\/span>
\n            (‘uReserve’,c_ubyte)]<\/span>
\n>>> r=Req()<\/span>
\n>>> sizeof(r)<\/span>
\n8<\/span>
\n>>> r.uUnit=1<\/span>
\n>>> print r.uUnit<\/span>
\n1<\/span>
\n>>> r.uUnit=2<\/span>
\n>>> print r.uUnit<\/span><\/p>\n

ctypes\u5e93\u7684\u6700\u4e3b\u8981\u4f5c\u7528\u5176\u5b9e\u662f\u7528\u4e8epython\u7a0b\u5e8f\u8c03\u7528c\u7f16\u8bd1\u5668\u751f\u6210\u7684\u5e93\u548cdll, \u4f46\u6211\u4eec\u8fd9\u91cc\u53ea\u7528\u5230\u6570\u636e\u7ed3\u6784\u8fd9\u4e00\u5757.<\/span><\/p>\n

ctypes\u5728\u4f7f\u7528\u65f6\u6709\u4ee5\u4e0b\u6ce8\u610f\u4e8b\u9879:<\/span><\/p>\n

\u81ea\u5b9a\u4e49\u7684\u7ed3\u6784\u4f53\u7c7b\u5fc5\u987b\u7ee7\u627fStructure\u6216Union\u7c7b;<\/span>
\n\u81ea\u5b9a\u4e49\u7684\u7ed3\u6784\u4f53\u7c7b\u4e2d\u5fc5\u987b\u5b9a\u4e49\u4e00\u4e2a\u540d\u4e3afields\u7684\u5217\u8868\u53d8\u91cf, \u5176\u4e2d\u6bcf\u4e2a\u5143\u7d20\u662f\u4e00\u4e2atuple, \u5b9a\u4e49\u4e86\u7ed3\u6784\u4f53\u6bcf\u4e2a\u6570\u636e\u5355\u5143\u4fe1\u606f, \u683c\u5f0f\u662f(\u2018\u53d8\u91cf\u540d\u5b57\u7b26\u4e32\u2019, \u53d8\u91cf\u6570\u636e\u7c7b\u578b [, \u6bd4\u7279\u6570])<\/span>
\n\u5b9a\u4e49\u4e86class\u540e, \u53ef\u4ee5\u7528sizeof(\u7c7b\u540d)\u67e5\u770b\u6570\u636e\u4f53\u5b57\u8282\u6570, \u548cc\u8bed\u8a00\u4e00\u6837. \u7136\u540e\u7528\u5b9e\u4f8b\u540d.\u6210\u5458\u540d\u8fdb\u884c\u76f8\u5e94\u6570\u636e\u5355\u5143\u7684\u8bbf\u95ee, \u5982\u679c\u7ee7\u627f\u540e\u5b9a\u4e49\u4e86init()\u65b9\u6cd5, \u8fd8\u53ef\u4ee5\u8fdb\u884c\u7c7b\u7684\u521d\u59cb\u5316\u64cd\u4f5c<\/span>
\n3. \u4e32\u884c\u6570\u636e\u6d41\u5904\u7406<\/span><\/p>\n

\u6709\u4e86\u7ed3\u6784\u4f53, \u4e0a\u9762\u7684\u4e09\u6761\u8981\u6c42\u6ee1\u8db3\u4e86\u4fe9\u4e2a, \u5173\u4e8e\u7b2c\u4e09\u4e2a\u8981\u6c42, ctypes\u867d\u7136\u63d0\u4f9b\u4e86cast()\u65b9\u6cd5, \u4f46\u7ecf\u8fc7\u6211\u7814\u7a76, \u53d1\u73b0cast\u5176\u5b9e\u53ea\u80fd\u5b9e\u73b0\u7b80\u5355\u7684\u6570\u7ec4\u7b49\u7ed3\u6784\u7684\u6570\u636e\u7c7b\u578b\u6307\u9488\u8f6c\u6362, \u4f46\u65e0\u6cd5\u50cfc\u90a3\u6837\u5c06\u7ed3\u6784\u4f53\u5bf9\u8c61\u5730\u5740\u8f6c\u6362\u6210\u5b57\u8282\u5730\u5740\u7684. \u8fd9\u79cd\u60c5\u51b5\u4e0b\u5c31\u9700\u8981python\u7684\u53e6\u4e00\u4e2a\u5e93:struct<\/span><\/p>\n

struct\u662f\u4e13\u95e8\u7528\u4e8e\u7ed3\u6784\u4f53\u4e0e\u6570\u636e\u6d41\u8f6c\u6362\u7684\u5e93, \u6211\u4eec\u7528\u5230\u7684\u4e3b\u8981\u65b9\u6cd5\u662fpack()\u548cunpack(). pack()\u7684\u4f7f\u7528\u8bf4\u660e\u5982\u4e0b:<\/span><\/p>\n

struct.pack(fmt, v1, v2, \u2026) <\/span>
\nReturn a string containing the values v1, v2, \u2026 packed according to the given format. The arguments must match the values required by the format exactly.<\/span>
\n\u4e3e\u4e2a\u4f8b\u5b50:<\/span><\/p>\n

>>> pack(‘BHB’,1,2,3)<\/span>
\n‘\\x01\\x00\\x02\\x00\\x03’<\/span><\/p>\n

pack()\u7684\u7528\u6cd5\u548cformat()\u5f88\u50cf, \u7b2c\u4e00\u4e2a\u53c2\u6570\u7528\u4e00\u4e2a\u5b57\u7b26\u4e32\u6307\u660e\u4e86\u8981\u8f6c\u6362\u7684\u683c\u5f0f, \u4f8b\u5982\u2019B\u2019\u8868\u793a8\u4f4d\u65e0\u7b26\u53f7\u6574\u6570, \u2018H\u2019\u8868\u793a16\u4f4d\u65e0\u7b26\u53f7\u6574\u6570\u7b49\u7b49, \u5177\u4f53\u8be6\u89c1python\u5e2e\u52a9\u91cc\u5173\u4e8estruct\u5e93\u7684\u8bf4\u660e. \u8fd9\u91cc\u7684\u2019BHB\u2019\u5c31\u7b49\u4e8e\u6307\u660e\u4e86, \u5c06\u540e\u9762\u7684\u4e09\u4e2a\u6570\u8f6c\u6210\u5b57\u8282\u6d41, \u7b2c\u4e00\u4e2a\u6570\u4ee58\u4f4d\u65e0\u7b26\u53f7\u6570\u8868\u793a, \u7b2c\u4e8c\u4e2a\u4ee516\u4f4d\u65e0\u7b26\u53f7\u6570\u8868\u793a, \u7b2c\u4e09\u4e2a\u4ee58\u4f4d\u65e0\u7b26\u53f7\u6570\u8868\u793a.<\/span><\/p>\n

\u7b49\u7b49! \u54ea\u91cc\u4e0d\u5bf9\u554a? \u4e24\u4e2a8\u4f4d\u65e0\u7b26\u53f7\u6570, \u4e00\u4e2a16\u4f4d\u65e0\u7b26\u53f7\u6570, \u52a0\u8d77\u6765\u5e94\u8be54\u4e2a\u5b57\u8282\u624d\u5bf9. \u53ef\u662f\u6211\u4eec\u770b\u8f6c\u6362\u7ed3\u679c\u2019\\x01\\x00\\x02\\x00\\x03\u2019\u4e00\u5171\u662f\u4e94\u4e2a\u5b57\u8282, \u6700\u540e\u4e00\u4e2a3\u4e5f\u88ab\u5f5316\u65e0\u7b26\u53f7\u6570\u5904\u7406\u4e86, \u96be\u9053\u662fbug\u4e86?<\/span><\/p>\n

\u8fd9\u4e2a\u95ee\u9898\u5176\u5b9e\u5728\u5e2e\u52a9\u6587\u6863\u91cc\u4e5f\u8bf4\u7684\u5f88\u6e05\u695a\u4e86, \u8fd9\u662f\u6240\u8c13machine\u2019s native format\u548cstandard format\u7684\u533a\u522b. \u7b80\u800c\u8a00\u4e4b\u5c31\u662f, \u5bf9\u4e8e\u6709\u4e9bC\u7f16\u8bd1\u5668, \u5982\u679c\u6ca1\u6709\u505a\u7279\u6b8a\u7f16\u8bd1\u7ea6\u675f, \u51fa\u4e8e\u5904\u7406\u5b57\u5bbd\u7684\u8003\u8651, \u5bf9\u7c7b\u4f3cunsigned char\u8fd9\u6837\u7684\u6570\u636e, \u5e76\u975e\u771f\u7684\u75281\u5b57\u8282\u8868\u793a, \u800c\u662f\u7528\u5904\u7406\u65f6\u6700\u9002\u5408cpu\u5bc4\u5b58\u5668\u7684\u957f\u5ea6\u8868\u793a, \u6bd4\u5982\u8ddf\u5728\u4e00\u4e2a\u65e0\u7b26\u53f716\u4f4d\u6570\u540e\u9762\u7684\u4e00\u4e2a\u65e0\u7b26\u53f78\u4f4d\u6570, \u5c31\u540c\u6837\u752816\u4f4d\u4f4d\u5bbd\u8868\u793a. \u8fd9\u6837\u5c3d\u7ba1\u6d6a\u8d39\u4e86\u5185\u5b58, \u4f46\u5728\u5bfb\u5740\u8d4b\u503c\u7b49\u5904\u7406\u8d77\u6765\u66f4\u6709\u6548\u7387\u2026 \u603b\u800c\u8a00\u4e4b, \u5982\u679c\u4e00\u5b9a\u8981\u6c42\u4e25\u683c\u76848\u4f4d\u548c16\u4f4d, \u5c31\u9700\u8981\u4f7f\u7528standard format, \u5c31\u662f\u5728\u683c\u5f0f\u5b57\u7b26\u4e32\u7684\u9996\u5b57\u6bcd\u52a0\u4ee5\u9650\u5b9a, \u5982:<\/span><\/p>\n

>>> pack(‘>BhB’,1,2,3)<\/span>
\n‘\\x01\\x00\\x02\\x03’<\/span><\/p>\n

\u8fd9\u91cc\u7684>\u8868\u793a: \u5b57\u8282\u6d41\u8f6c\u6362\u4f7f\u7528standard format, \u800c\u4e14\u4f7f\u7528\u5927\u7aef\u6a21\u5f0f.<\/span><\/p>\n

4. \u7ed3\u6784\u4f53\u7684\u5b57\u8282\u6d41\u8f6c\u6362<\/span><\/p>\n

\u6709\u4e86pack()\u8fd9\u4e2a\u5de5\u5177, \u518d\u56de\u5230\u524d\u9762\u7684\u7ed3\u6784\u4f53\u5b57\u8282\u6d41\u8f6c\u6362\u4e0a\u2026 \u53d1\u73b0\u8fd8\u662f\u6709\u95ee\u9898\u554a, \u56e0\u4e3apack()\u53ef\u4ee5\u5b9e\u73b0\u5355\u5b57\u8282, \u53cc\u5b57\u8282, \u5374\u6ca1\u6cd5\u5bf9bit field\u8fd9\u79cd\u4e1c\u897f\u64cd\u4f5c. \u53c8\u8be5\u600e\u4e48\u89e3\u51b3\u5462.<\/span><\/p>\n

\u5176\u5b9e\u8fd9\u4e2a\u95ee\u9898, \u6211\u4e5f\u6ca1\u627e\u5230\u597d\u7684\u89e3\u51b3\u529e\u6cd5, \u6bd5\u7adfpack()\u9700\u8981\u6211\u4eec\u624b\u5de5\u4e00\u4e2a\u4e2a\u6307\u5b9a\u53d8\u91cf, \u5b9a\u4e49\u987a\u5e8f\u548c\u5b57\u8282\u957f\u5ea6. \u8fd9\u91cc\u6211\u63d0\u4f9b\u4e00\u79cd\u89e3\u51b3\u65b9\u6848, \u90a3\u5c31\u662f\u501f\u7528Union.<\/span><\/p>\n

\u4ecd\u4ee5\u524d\u9762\u7684\u7ed3\u6784\u4f53\u4e3a\u4f8b, \u6362\u4e00\u79cd\u5199\u6cd5:<\/span><\/p>\n

>>> class Flag_Struct(Structure):<\/span>
\n    _fields_=[(‘uRouter’,c_ubyte,1),<\/span>
\n            (‘uSubNode’,c_ubyte,1),<\/span>
\n            (‘uCM’,c_ubyte,1),<\/span>
\n            (‘uCD’,c_ubyte,1),<\/span><\/p>\n

\n\t            (‘uLevel’,c_ubyte,4)]<\/span>\n<\/p>\n

\n\t
\n<\/span>\n<\/p>\n

>>> class Flag_Union(Union):<\/span>
\n    _fields_=[(‘whole’,c_ubyte),<\/span><\/p>\n

\n\t            (‘flag_struct’,Flag_Struct)]<\/span>\n<\/p>\n

\n\t
\n<\/span>\n<\/p>\n

>>> class Channel_Struct(Structure):<\/span>
\n    _fields_=[(‘uChannel’,c_ubyte,4),<\/span>
\n            (‘uErrBate’,c_ubyte,4)]<\/span><\/p>\n

\n>>> class Channel_Union(Union):<\/span>
\n    _fields_=[(‘whole’,c_ubyte),<\/span>
\n            (‘channel_struct’,Channel_Struct)]<\/span><\/p>\n

>>> class Speed_Struct(Structure):<\/span>
\n    _fields_=[(‘uSpeed’,c_ushort,15),<\/span>
\n            (‘uUnit’,c_ushort,1)]<\/span><\/p>\n

>>> class Speed_Union(Union):<\/span>
\n    _fields_=[(‘whole’,c_ushort),<\/span>
\n            (‘speed_struct’,Speed_Struct)]<\/span><\/p>\n

>>> class Req(Structure):<\/span>
\n    _pack_=1<\/span>
\n    _fields_=[(‘flag’,Flag_Union),<\/span>
\n            (‘channel’,Channel_Union),<\/span>
\n            (‘uResBytes’,c_ubyte),<\/span>
\n            (‘speed’,Speed_Union),<\/span>
\n            (‘uReserve’,c_ubyte)]<\/span><\/p>\n

\u7b80\u800c\u8a00\u4e4b, \u5c31\u662f\u6240\u6709\u6d89\u53cabit-field\u7684\u5b57\u6bb5\u90fd\u7528\u4e00\u4e2aunion\u548c\u5b50struct\u6765\u8868\u793a. (\u5176\u4e2dpack\u662f\u4e3a\u4e861\u5b57\u8282\u5bf9\u9f50, \u539f\u56e0\u4e0e\u4e0a\u4e00\u8282\u4ecb\u7ecd\u8fc7\u7684native format\u548cstandard format\u7c7b\u4f3c). \u8fd9\u6837\u505a\u7684\u76ee\u7684\u662f\u4e3a\u4e86\u6298\u4e2d\u6bd4\u7279\u5b57\u6bb5\u8bbf\u95ee\u4e0e\u6574\u5b57\u8282\u7684\u8f6c\u5316\u5904\u7406, \u4f8b\u5982:<\/span><\/p>\n

>>> r=Req()<\/span>
\n>>> r.speed.speed_struct.uUnit=1<\/span>
\n>>> r.flag.flag_struct.uLevel=0xf<\/span>
\n>>> ack(‘>BBBHB’,r.flag.whole,r.channel.whole,r.uResBytes,r.speed.whole,r.uReserve)<\/span>
\n‘\\xf0\\x00\\x00\\x80\\x00\\x00’<\/span><\/p>\n

5. \u4e00\u79cd\u66f4\u7b80\u5355\u7684\u5b57\u8282\u6d41\u8f6c\u5316\u65b9\u6cd5<\/strong><\/span><\/p>\n

\u540e\u6765\u901a\u8fc7\u4ed4\u7ec6\u67e5\u770b\u6587\u6863, \u53d1\u73b0\u5176\u5b9ectypes\u91cc\u63d0\u4f9b\u4e86\u4e00\u79cd\u66f4\u7b80\u5355\u7684\u5b57\u8282\u6d41\u8f6c\u5316\u65b9\u6cd5:<\/span>
\nstring_at(addressof(r),sizeof(r))<\/span><\/p>\n

addressof()\u548cstring_at\u90fd\u662fctypes\u91cc\u63d0\u4f9b\u7684\u65b9\u6cd5. \u8fd9\u662f\u6700\u63a5\u8fd1\u4e8e\u539f\u751fc\u7684\u5904\u7406\u65b9\u6cd5, \u8fd9\u6837\u8fdeunion\u90fd\u4e0d\u7528\u5b9a\u4e49\u4e86<\/span><\/p>\n

>>> class Req(Structure):<\/span>
\n    _pack_=1<\/span>
\n    _fields_=[(‘uRouter’,c_ubyte,1),<\/span>
\n            (‘uSubNode’,c_ubyte,1),<\/span>
\n            (‘uCM’,c_ubyte,1),<\/span>
\n            (‘uCD’,c_ubyte,1),<\/span>
\n            (‘uLevel’,c_ubyte,4),<\/span>
\n            (‘uChannel’,c_ubyte,4),<\/span>
\n            (‘uErrBate’,c_ubyte,4),<\/span>
\n            (‘uResBytes’,c_ubyte),<\/span>
\n            (‘uSpeed’,c_ushort,15),<\/span>
\n            (‘uUnit’,c_ushort,1),<\/span>
\n            (‘uReserve’,c_ubyte)]<\/span><\/p>\n

>>> sizeof(Req)<\/span>
\n6<\/span>
\n>>> r=Req()<\/span>
\n>>> r.uUnit=1<\/span>
\n>>> r.uCM=1<\/span>
\n>>> string_at(addressof(r),sizeof(r))<\/span>
\n‘\\x04\\x00\\x00\\x00\\x80\\x00’<\/span><\/p>\n

\u5982\u679c\u9700\u8981\u5927\u7aef\u7684\u6570\u636e\u7ed3\u6784, \u8d85\u7c7b\u9700\u8981\u9009\u62e9BigEndianStructure, \u6b64\u65f6bit-field\u7684\u5b9a\u4e49\u4e5f\u662f\u4ece\u9ad8\u5230\u4f4e\u7684, \u9700\u8981\u91cd\u65b0\u8c03\u6574\u5b9a\u4e49\u7684\u987a\u5e8f, \u5982\u4e0b:<\/span><\/p>\n

>>> class Req(BigEndianStructure):<\/span>
\n    _pack_=1<\/span>
\n    _fields_=[(‘uLevel’,c_ubyte,4),<\/span>
\n            (‘uCD’,c_ubyte,1),<\/span>
\n            (‘uCM’,c_ubyte,1),<\/span>
\n            (‘uSubNode’,c_ubyte,1),<\/span>
\n            (‘uRouter’,c_ubyte,1),<\/span>
\n            (‘uErrBate’,c_ubyte,4),<\/span>
\n            (‘uChannel’,c_ubyte,4),<\/span>
\n            (‘uResBytes’,c_ubyte),<\/span>
\n            (‘uUnit’,c_ushort,1),<\/span>
\n            (‘uSpeed’,c_ushort,15),<\/span>
\n            (‘uReserve’,c_ubyte)]<\/span><\/p>\n

>>> r=Req()<\/span>
\n>>> r.uLevel=0xf<\/span>
\n>>> r.uUnit=1<\/span>
\n>>> string_at(addressof(r),sizeof(r))<\/span>
\n‘\\xf0\\x00\\x00\\x80\\x00\\x00’<\/span><\/p>\n

\u6700\u540e\u6709\u4eba\u8981\u95ee\u4e86: Python\u662f\u4e00\u79cd\u9ad8\u7ea7\u8bed\u8a00, \u4e3a\u5565\u8981\u505a\u8fd9\u4e48\u4f4e\u7ea7\u7684\u4e8b\u60c5\u5462? \u5176\u5b9e\u672f\u4e1a\u6709\u4e13\u653b, \u5bf9\u4e8e\u5d4c\u5165\u5f0f\u901a\u4fe1, \u7528python\u505a\u9ad8\u5c42\u7684\u8f85\u52a9\u6d4b\u8bd5\u5de5\u5177\u662f\u975e\u5e38\u65b9\u4fbf\u7684.<\/span><\/p>\n

(2015-12-14 \u8865\u5145)\u5c06\u5b57\u8282\u6d41\u704c\u6ce8\u5230\u7ed3\u6784\u4f53\u4e2d\u5b9e\u73b0\u89e3\u6790\u7684\u65b9\u6cd5:<\/strong><\/span><\/p>\n

r = Req()<\/span>
\ns = io_rcv()        #receive byte stream from io<\/span>
\nmemmove(addressof(r),s,sizeof(Req))<\/span>
\n…<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

\n\thttp:\/\/blog.csdn.net\/machael_sonic\/article\/details\/50266499<\/a><\/span>\n<\/p>\n

\n\t
\n<\/span>\n<\/p>\n

\n\t1. \u7528C\/C++\u5b9e\u73b0\u7684\u7ed3\u6784\u5316\u6570\u636e\u5904\u7406<\/span>\n<\/p>\n

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