{"id":226,"date":"2011-08-09T10:11:02","date_gmt":"2011-08-09T00:11:02","guid":{"rendered":"http:\/\/www.reenadu.com\/?p=226"},"modified":"2011-08-09T10:11:02","modified_gmt":"2011-08-09T00:11:02","slug":"cyclic-redundancy-check-crc-in-c","status":"publish","type":"post","link":"https:\/\/nickdu.com\/?p=226","title":{"rendered":"Cyclic Redundancy Check (CRC) in C#"},"content":{"rendered":"<p>Microsoft .Net Framework is so powerful, and it provides so many common libraries to use. However, recently I am working on a legacy project to work out <a href=\"http:\/\/en.wikipedia.org\/wiki\/Cyclic_redundancy_check\" target=\"_blank\">CRC32<\/a>, and I can find no where. OK, I have to DIY. If you need it by chance, here are the source code.<\/p>\n<pre lang=\"csharp\">\/\/\/ \n\/\/\/ Calculates a 32bit Cyclic Redundancy Checksum (CRC) using the\n\/\/\/ same polynomial used by Zip.\n\/\/\/ \npublic class CRC32 : HashAlgorithm\n{\n\n    private static readonly UInt32[] crc32Table =\n    {\n\t0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,\n\t0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,\n\t0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,\n\t0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,\n\t0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,\n\t0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,\n\t0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,\n\t0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,\n\t0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,\n\t0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,\n\t0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,\n\t0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,\n\t0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,\n\t0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,\n\t0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,\n\t0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,\n\t0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,\n\t0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,\n\t0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,\n\t0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,\n\t0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,\n\t0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,\n\t0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,\n\t0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,\n\t0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,\n\t0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,\n\t0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,\n\t0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,\n\t0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,\n\t0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,\n\t0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,\n\t0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,\n\t0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,\n\t0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,\n\t0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,\n\t0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,\n\t0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,\n\t0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,\n\t0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,\n\t0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,\n\t0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,\n\t0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,\n\t0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,\n\t0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,\n\t0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,\n\t0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,\n\t0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,\n\t0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,\n\t0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,\n\t0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,\n\t0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,\n\t0x2d02ef8d\n    };\n\n    private UInt32 hash;\n    private UInt32 seed;\n    private const UInt32 DefaultSeed = 0xffffffff;\n\n    \/\/\/ \n    \/\/\/ Construct an instance of the CRC32 class, pre-initialising the table\n    \/\/\/ for speed of lookup.\n    \/\/\/ \n    public CRC32()\n    {\n        this.seed = DefaultSeed;\n        Initialize();\n    }\n\n    public override int HashSize\n    {\n        get\n        {\n            return 32;\n        }\n    }\n\n    public CRC32(UInt32 seed)\n    {\n        this.seed = seed;\n        Initialize();\n    }\n\n    protected override byte[] HashFinal()\n    {\n        hash = ~hash;\n        this.HashValue = new byte[] {\n\t\t\t\t\t\t(byte)((hash>>24) & 0xff),\n\t\t\t\t\t\t(byte)((hash>>16) & 0xff),\n\t\t\t\t\t\t(byte)((hash>>8) & 0xff),\n\t\t\t\t\t\t(byte)(hash & 0xff)\n\t\t\t\t\t\t};\n        return HashValue;\n    }\n\n    protected override void HashCore(byte[] buffer, int start, int length)\n    {\n        for (int i = start; i<length; i++)         \n        {             \n            unchecked             \n            {                 \n                hash = ((hash) >>8) \n                          ^ crc32Table[(buffer[i]) ^ ((hash) & 0x000000FF)];\n            }\n        }\n    }\n\n    public override void Initialize()\n    {\n        hash = seed;\n    }\n}\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Microsoft .Net Framework is so powerful, and it provides so many common libraries to use. However, recently I am working on a legacy project to work out CRC32, and I can find no where. OK, I have to DIY. If you need it by chance, here are the source code. \/\/\/ \/\/\/ Calculates a 32bit &hellip; <a href=\"https:\/\/nickdu.com\/?p=226\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Cyclic Redundancy Check (CRC) in C#&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,2],"tags":[],"class_list":["post-226","post","type-post","status-publish","format-standard","hentry","category-net","category-it"],"_links":{"self":[{"href":"https:\/\/nickdu.com\/index.php?rest_route=\/wp\/v2\/posts\/226","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nickdu.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nickdu.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nickdu.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/nickdu.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=226"}],"version-history":[{"count":0,"href":"https:\/\/nickdu.com\/index.php?rest_route=\/wp\/v2\/posts\/226\/revisions"}],"wp:attachment":[{"href":"https:\/\/nickdu.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=226"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nickdu.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=226"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nickdu.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=226"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}