wsutil/crc16.c

   1 /* crc16.c
   2  * CRC-16 routine
   3  *
   4  * 2004 Richard van der Hoff <richardv@mxtelecom.com>
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * SPDX-License-Identifier: GPL-2.0-or-later
  11  *
  12  * References:
  13  *  "A Painless Guide to CRC Error Detection Algorithms", Ross Williams
  14  *      http://www.repairfaq.org/filipg/LINK/F_crc_v3.html
  15  *
  16  *  ITU-T Recommendation V.42 (2002), "Error-Correcting Procedures for
  17  *      DCEs using asynchronous-to-synchronous conversion", Para. 8.1.1.6.1
  18  */
  19
  20 #include "config.h"
  21
  22 #include <wsutil/crc16.h>
  23
  24 /*****************************************************************/
  25
  26 /*
  27  * Table for the CCITT/ITU/CRC-16 16-bit CRC
  28  *
  29  * Polynomial is
  30  *
  31  *     x^16 + x^12 + x^5 + 1
  32  */
  33
  34 /*                                                               */
  35 /* CRC LOOKUP TABLE                                              */
  36 /* ================                                              */
  37 /* The following CRC lookup table was generated automagically    */
  38 /* by the Rocksoft^tm Model CRC Algorithm Table Generation       */
  39 /* Program V1.0 using the following model parameters:            */
  40 /*                                                               */
  41 /*    Width   : 2 bytes.                                         */
  42 /*    Poly    : 0x1021                                           */
  43 /*    Reverse : true.                                           */
  44 /*                                                               */
  45 /* For more information on the Rocksoft^tm Model CRC Algorithm,  */
  46 /* see the document titled "A Painless Guide to CRC Error        */
  47 /* Detection Algorithms" by Ross Williams.  See                  */
  48 /*                                                               */
  49 /*    http://www.ross.net/crc/crcpaper.html                      */
  50 /*                                                               */
  51 /* which links to a text version and an HTML-but-not-all-on-one- */
  52 /* page version, or various HTML-all-on-one-page versions such   */
  53 /* as the one at                                                 */
  54 /*                                                               */
  55 /*    http://www.geocities.com/SiliconValley/Pines/8659/crc.htm  */
  56 /*                                                               */
  57 /* (search for the title to find others).                        */
  58 /*                                                               */
  59 /*****************************************************************/
  60
  61 static const unsigned crc16_ccitt_table_reverse[256] =
  62 {
  63     0x0000, 0x1189, 0x2312, 0x329B, 0x4624, 0x57AD, 0x6536, 0x74BF,
  64     0x8C48, 0x9DC1, 0xAF5A, 0xBED3, 0xCA6C, 0xDBE5, 0xE97E, 0xF8F7,
  65     0x1081, 0x0108, 0x3393, 0x221A, 0x56A5, 0x472C, 0x75B7, 0x643E,
  66     0x9CC9, 0x8D40, 0xBFDB, 0xAE52, 0xDAED, 0xCB64, 0xF9FF, 0xE876,
  67     0x2102, 0x308B, 0x0210, 0x1399, 0x6726, 0x76AF, 0x4434, 0x55BD,
  68     0xAD4A, 0xBCC3, 0x8E58, 0x9FD1, 0xEB6E, 0xFAE7, 0xC87C, 0xD9F5,
  69     0x3183, 0x200A, 0x1291, 0x0318, 0x77A7, 0x662E, 0x54B5, 0x453C,
  70     0xBDCB, 0xAC42, 0x9ED9, 0x8F50, 0xFBEF, 0xEA66, 0xD8FD, 0xC974,
  71     0x4204, 0x538D, 0x6116, 0x709F, 0x0420, 0x15A9, 0x2732, 0x36BB,
  72     0xCE4C, 0xDFC5, 0xED5E, 0xFCD7, 0x8868, 0x99E1, 0xAB7A, 0xBAF3,
  73     0x5285, 0x430C, 0x7197, 0x601E, 0x14A1, 0x0528, 0x37B3, 0x263A,
  74     0xDECD, 0xCF44, 0xFDDF, 0xEC56, 0x98E9, 0x8960, 0xBBFB, 0xAA72,
  75     0x6306, 0x728F, 0x4014, 0x519D, 0x2522, 0x34AB, 0x0630, 0x17B9,
  76     0xEF4E, 0xFEC7, 0xCC5C, 0xDDD5, 0xA96A, 0xB8E3, 0x8A78, 0x9BF1,
  77     0x7387, 0x620E, 0x5095, 0x411C, 0x35A3, 0x242A, 0x16B1, 0x0738,
  78     0xFFCF, 0xEE46, 0xDCDD, 0xCD54, 0xB9EB, 0xA862, 0x9AF9, 0x8B70,
  79     0x8408, 0x9581, 0xA71A, 0xB693, 0xC22C, 0xD3A5, 0xE13E, 0xF0B7,
  80     0x0840, 0x19C9, 0x2B52, 0x3ADB, 0x4E64, 0x5FED, 0x6D76, 0x7CFF,
  81     0x9489, 0x8500, 0xB79B, 0xA612, 0xD2AD, 0xC324, 0xF1BF, 0xE036,
  82     0x18C1, 0x0948, 0x3BD3, 0x2A5A, 0x5EE5, 0x4F6C, 0x7DF7, 0x6C7E,
  83     0xA50A, 0xB483, 0x8618, 0x9791, 0xE32E, 0xF2A7, 0xC03C, 0xD1B5,
  84     0x2942, 0x38CB, 0x0A50, 0x1BD9, 0x6F66, 0x7EEF, 0x4C74, 0x5DFD,
  85     0xB58B, 0xA402, 0x9699, 0x8710, 0xF3AF, 0xE226, 0xD0BD, 0xC134,
  86     0x39C3, 0x284A, 0x1AD1, 0x0B58, 0x7FE7, 0x6E6E, 0x5CF5, 0x4D7C,
  87     0xC60C, 0xD785, 0xE51E, 0xF497, 0x8028, 0x91A1, 0xA33A, 0xB2B3,
  88     0x4A44, 0x5BCD, 0x6956, 0x78DF, 0x0C60, 0x1DE9, 0x2F72, 0x3EFB,
  89     0xD68D, 0xC704, 0xF59F, 0xE416, 0x90A9, 0x8120, 0xB3BB, 0xA232,
  90     0x5AC5, 0x4B4C, 0x79D7, 0x685E, 0x1CE1, 0x0D68, 0x3FF3, 0x2E7A,
  91     0xE70E, 0xF687, 0xC41C, 0xD595, 0xA12A, 0xB0A3, 0x8238, 0x93B1,
  92     0x6B46, 0x7ACF, 0x4854, 0x59DD, 0x2D62, 0x3CEB, 0x0E70, 0x1FF9,
  93     0xF78F, 0xE606, 0xD49D, 0xC514, 0xB1AB, 0xA022, 0x92B9, 0x8330,
  94     0x7BC7, 0x6A4E, 0x58D5, 0x495C, 0x3DE3, 0x2C6A, 0x1EF1, 0x0F78
  95 };
  96
  97 /* Same as above, only without reverse (Reverse=false) */
  98 static const unsigned crc16_ccitt_table[256] =
  99 {
 100     0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
 101     0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
 102     0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
 103     0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
 104     0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
 105     0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
 106     0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
 107     0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
 108     0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
 109     0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
 110     0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
 111     0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
 112     0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
 113     0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
 114     0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
 115     0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
 116     0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
 117     0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
 118     0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
 119     0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
 120     0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
 121     0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
 122     0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
 123     0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
 124     0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
 125     0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
 126     0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
 127     0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
 128     0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
 129     0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
 130     0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
 131     0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
 132 };
 133
 134 /* This table was compiled using the polynom 0x5935 */
 135 static const unsigned crc16_precompiled_5935[256] =
 136 {
 137     0x0000, 0x5935, 0xB26A, 0xEB5F, 0x3DE1, 0x64D4, 0x8F8B, 0xD6BE,
 138     0x7BC2, 0x22F7, 0xC9A8, 0x909D, 0x4623, 0x1F16, 0xF449, 0xAD7C,
 139     0xF784, 0xAEB1, 0x45EE, 0x1CDB, 0xCA65, 0x9350, 0x780F, 0x213A,
 140     0x8C46, 0xD573, 0x3E2C, 0x6719, 0xB1A7, 0xE892, 0x03CD, 0x5AF8,
 141     0xB63D, 0xEF08, 0x0457, 0x5D62, 0x8BDC, 0xD2E9, 0x39B6, 0x6083,
 142     0xCDFF, 0x94CA, 0x7F95, 0x26A0, 0xF01E, 0xA92B, 0x4274, 0x1B41,
 143     0x41B9, 0x188C, 0xF3D3, 0xAAE6, 0x7C58, 0x256D, 0xCE32, 0x9707,
 144     0x3A7B, 0x634E, 0x8811, 0xD124, 0x079A, 0x5EAF, 0xB5F0, 0xECC5,
 145     0x354F, 0x6C7A, 0x8725, 0xDE10, 0x08AE, 0x519B, 0xBAC4, 0xE3F1,
 146     0x4E8D, 0x17B8, 0xFCE7, 0xA5D2, 0x736C, 0x2A59, 0xC106, 0x9833,
 147     0xC2CB, 0x9BFE, 0x70A1, 0x2994, 0xFF2A, 0xA61F, 0x4D40, 0x1475,
 148     0xB909, 0xE03C, 0x0B63, 0x5256, 0x84E8, 0xDDDD, 0x3682, 0x6FB7,
 149     0x8372, 0xDA47, 0x3118, 0x682D, 0xBE93, 0xE7A6, 0x0CF9, 0x55CC,
 150     0xF8B0, 0xA185, 0x4ADA, 0x13EF, 0xC551, 0x9C64, 0x773B, 0x2E0E,
 151     0x74F6, 0x2DC3, 0xC69C, 0x9FA9, 0x4917, 0x1022, 0xFB7D, 0xA248,
 152     0x0F34, 0x5601, 0xBD5E, 0xE46B, 0x32D5, 0x6BE0, 0x80BF, 0xD98A,
 153     0x6A9E, 0x33AB, 0xD8F4, 0x81C1, 0x577F, 0x0E4A, 0xE515, 0xBC20,
 154     0x115C, 0x4869, 0xA336, 0xFA03, 0x2CBD, 0x7588, 0x9ED7, 0xC7E2,
 155     0x9D1A, 0xC42F, 0x2F70, 0x7645, 0xA0FB, 0xF9CE, 0x1291, 0x4BA4,
 156     0xE6D8, 0xBFED, 0x54B2, 0x0D87, 0xDB39, 0x820C, 0x6953, 0x3066,
 157     0xDCA3, 0x8596, 0x6EC9, 0x37FC, 0xE142, 0xB877, 0x5328, 0x0A1D,
 158     0xA761, 0xFE54, 0x150B, 0x4C3E, 0x9A80, 0xC3B5, 0x28EA, 0x71DF,
 159     0x2B27, 0x7212, 0x994D, 0xC078, 0x16C6, 0x4FF3, 0xA4AC, 0xFD99,
 160     0x50E5, 0x09D0, 0xE28F, 0xBBBA, 0x6D04, 0x3431, 0xDF6E, 0x865B,
 161     0x5FD1, 0x06E4, 0xEDBB, 0xB48E, 0x6230, 0x3B05, 0xD05A, 0x896F,
 162     0x2413, 0x7D26, 0x9679, 0xCF4C, 0x19F2, 0x40C7, 0xAB98, 0xF2AD,
 163     0xA855, 0xF160, 0x1A3F, 0x430A, 0x95B4, 0xCC81, 0x27DE, 0x7EEB,
 164     0xD397, 0x8AA2, 0x61FD, 0x38C8, 0xEE76, 0xB743, 0x5C1C, 0x0529,
 165     0xE9EC, 0xB0D9, 0x5B86, 0x02B3, 0xD40D, 0x8D38, 0x6667, 0x3F52,
 166     0x922E, 0xCB1B, 0x2044, 0x7971, 0xAFCF, 0xF6FA, 0x1DA5, 0x4490,
 167     0x1E68, 0x475D, 0xAC02, 0xF537, 0x2389, 0x7ABC, 0x91E3, 0xC8D6,
 168     0x65AA, 0x3C9F, 0xD7C0, 0x8EF5, 0x584B, 0x017E, 0xEA21, 0xB314
 169 };
 170
 171 /* This table was compiled using the polynom 0x755B */
 172 static const unsigned crc16_precompiled_755B[] =
 173 {
 174     0x0000, 0x755b, 0xeab6, 0x9fed, 0xa037, 0xd56c, 0x4a81, 0x3fda,     /* 0x00 */
 175     0x3535, 0x406e, 0xdf83, 0xaad8, 0x9502, 0xe059, 0x7fb4, 0x0aef,     /* 0x08 */
 176     0x6a6a, 0x1f31, 0x80dc, 0xf587, 0xca5d, 0xbf06, 0x20eb, 0x55b0,     /* 0x10 */
 177     0x5f5f, 0x2a04, 0xb5e9, 0xc0b2, 0xff68, 0x8a33, 0x15de, 0x6085,     /* 0x18 */
 178     0xd4d4, 0xa18f, 0x3e62, 0x4b39, 0x74e3, 0x01b8, 0x9e55, 0xeb0e,     /* 0x20 */
 179     0xe1e1, 0x94ba, 0x0b57, 0x7e0c, 0x41d6, 0x348d, 0xab60, 0xde3b,     /* 0x28 */
 180     0xbebe, 0xcbe5, 0x5408, 0x2153, 0x1e89, 0x6bd2, 0xf43f, 0x8164,     /* 0x30 */
 181     0x8b8b, 0xfed0, 0x613d, 0x1466, 0x2bbc, 0x5ee7, 0xc10a, 0xb451,     /* 0x38 */
 182     0xdcf3, 0xa9a8, 0x3645, 0x431e, 0x7cc4, 0x099f, 0x9672, 0xe329,     /* 0x40 */
 183     0xe9c6, 0x9c9d, 0x0370, 0x762b, 0x49f1, 0x3caa, 0xa347, 0xd61c,     /* 0x48 */
 184     0xb699, 0xc3c2, 0x5c2f, 0x2974, 0x16ae, 0x63f5, 0xfc18, 0x8943,     /* 0x50 */
 185     0x83ac, 0xf6f7, 0x691a, 0x1c41, 0x239b, 0x56c0, 0xc92d, 0xbc76,     /* 0x58 */
 186     0x0827, 0x7d7c, 0xe291, 0x97ca, 0xa810, 0xdd4b, 0x42a6, 0x37fd,     /* 0x60 */
 187     0x3d12, 0x4849, 0xd7a4, 0xa2ff, 0x9d25, 0xe87e, 0x7793, 0x02c8,     /* 0x68 */
 188     0x624d, 0x1716, 0x88fb, 0xfda0, 0xc27a, 0xb721, 0x28cc, 0x5d97,     /* 0x70 */
 189     0x5778, 0x2223, 0xbdce, 0xc895, 0xf74f, 0x8214, 0x1df9, 0x68a2,     /* 0x78 */
 190     0xccbd, 0xb9e6, 0x260b, 0x5350, 0x6c8a, 0x19d1, 0x863c, 0xf367,     /* 0x80 */
 191     0xf988, 0x8cd3, 0x133e, 0x6665, 0x59bf, 0x2ce4, 0xb309, 0xc652,     /* 0x88 */
 192     0xa6d7, 0xd38c, 0x4c61, 0x393a, 0x06e0, 0x73bb, 0xec56, 0x990d,     /* 0x90 */
 193     0x93e2, 0xe6b9, 0x7954, 0x0c0f, 0x33d5, 0x468e, 0xd963, 0xac38,     /* 0x98 */
 194     0x1869, 0x6d32, 0xf2df, 0x8784, 0xb85e, 0xcd05, 0x52e8, 0x27b3,     /* 0xA0 */
 195     0x2d5c, 0x5807, 0xc7ea, 0xb2b1, 0x8d6b, 0xf830, 0x67dd, 0x1286,     /* 0xA8 */
 196     0x7203, 0x0758, 0x98b5, 0xedee, 0xd234, 0xa76f, 0x3882, 0x4dd9,     /* 0xB0 */
 197     0x4736, 0x326d, 0xad80, 0xd8db, 0xe701, 0x925a, 0x0db7, 0x78ec,     /* 0xB8 */
 198     0x104e, 0x6515, 0xfaf8, 0x8fa3, 0xb079, 0xc522, 0x5acf, 0x2f94,     /* 0xC0 */
 199     0x257b, 0x5020, 0xcfcd, 0xba96, 0x854c, 0xf017, 0x6ffa, 0x1aa1,     /* 0xC8 */
 200     0x7a24, 0x0f7f, 0x9092, 0xe5c9, 0xda13, 0xaf48, 0x30a5, 0x45fe,     /* 0xD0 */
 201     0x4f11, 0x3a4a, 0xa5a7, 0xd0fc, 0xef26, 0x9a7d, 0x0590, 0x70cb,     /* 0xD8 */
 202     0xc49a, 0xb1c1, 0x2e2c, 0x5b77, 0x64ad, 0x11f6, 0x8e1b, 0xfb40,     /* 0xE0 */
 203     0xf1af, 0x84f4, 0x1b19, 0x6e42, 0x5198, 0x24c3, 0xbb2e, 0xce75,     /* 0xE8 */
 204     0xaef0, 0xdbab, 0x4446, 0x311d, 0x0ec7, 0x7b9c, 0xe471, 0x912a,     /* 0xF0 */
 205     0x9bc5, 0xee9e, 0x7173, 0x0428, 0x3bf2, 0x4ea9, 0xd144, 0xa41f      /* 0xF8 */
 206 };
 207
 208 /* This table was compiled using the polynom: 0x9949 */
 209 static const unsigned crc16_precompiled_9949_reverse[] =
 210 {
 211     0x0000, 0x0ED2, 0x1DA4, 0x1376, 0x3B48, 0x359A, 0x26EC, 0x283E,
 212     0x7690, 0x7842, 0x6B34, 0x65E6, 0x4DD8, 0x430A, 0x507C, 0x5EAE,
 213     0xED20, 0xE3F2, 0xF084, 0xFE56, 0xD668, 0xD8BA, 0xCBCC, 0xC51E,
 214     0x9BB0, 0x9562, 0x8614, 0x88C6, 0xA0F8, 0xAE2A, 0xBD5C, 0xB38E,
 215     0xFF73, 0xF1A1, 0xE2D7, 0xEC05, 0xC43B, 0xCAE9, 0xD99F, 0xD74D,
 216     0x89E3, 0x8731, 0x9447, 0x9A95, 0xB2AB, 0xBC79, 0xAF0F, 0xA1DD,
 217     0x1253, 0x1C81, 0x0FF7, 0x0125, 0x291B, 0x27C9, 0x34BF, 0x3A6D,
 218     0x64C3, 0x6A11, 0x7967, 0x77B5, 0x5F8B, 0x5159, 0x422F, 0x4CFD,
 219     0xDBD5, 0xD507, 0xC671, 0xC8A3, 0xE09D, 0xEE4F, 0xFD39, 0xF3EB,
 220     0xAD45, 0xA397, 0xB0E1, 0xBE33, 0x960D, 0x98DF, 0x8BA9, 0x857B,
 221     0x36F5, 0x3827, 0x2B51, 0x2583, 0x0DBD, 0x036F, 0x1019, 0x1ECB,
 222     0x4065, 0x4EB7, 0x5DC1, 0x5313, 0x7B2D, 0x75FF, 0x6689, 0x685B,
 223     0x24A6, 0x2A74, 0x3902, 0x37D0, 0x1FEE, 0x113C, 0x024A, 0x0C98,
 224     0x5236, 0x5CE4, 0x4F92, 0x4140, 0x697E, 0x67AC, 0x74DA, 0x7A08,
 225     0xC986, 0xC754, 0xD422, 0xDAF0, 0xF2CE, 0xFC1C, 0xEF6A, 0xE1B8,
 226     0xBF16, 0xB1C4, 0xA2B2, 0xAC60, 0x845E, 0x8A8C, 0x99FA, 0x9728,
 227     0x9299, 0x9C4B, 0x8F3D, 0x81EF, 0xA9D1, 0xA703, 0xB475, 0xBAA7,
 228     0xE409, 0xEADB, 0xF9AD, 0xF77F, 0xDF41, 0xD193, 0xC2E5, 0xCC37,
 229     0x7FB9, 0x716B, 0x621D, 0x6CCF, 0x44F1, 0x4A23, 0x5955, 0x5787,
 230     0x0929, 0x07FB, 0x148D, 0x1A5F, 0x3261, 0x3CB3, 0x2FC5, 0x2117,
 231     0x6DEA, 0x6338, 0x704E, 0x7E9C, 0x56A2, 0x5870, 0x4B06, 0x45D4,
 232     0x1B7A, 0x15A8, 0x06DE, 0x080C, 0x2032, 0x2EE0, 0x3D96, 0x3344,
 233     0x80CA, 0x8E18, 0x9D6E, 0x93BC, 0xBB82, 0xB550, 0xA626, 0xA8F4,
 234     0xF65A, 0xF888, 0xEBFE, 0xE52C, 0xCD12, 0xC3C0, 0xD0B6, 0xDE64,
 235     0x494C, 0x479E, 0x54E8, 0x5A3A, 0x7204, 0x7CD6, 0x6FA0, 0x6172,
 236     0x3FDC, 0x310E, 0x2278, 0x2CAA, 0x0494, 0x0A46, 0x1930, 0x17E2,
 237     0xA46C, 0xAABE, 0xB9C8, 0xB71A, 0x9F24, 0x91F6, 0x8280, 0x8C52,
 238     0xD2FC, 0xDC2E, 0xCF58, 0xC18A, 0xE9B4, 0xE766, 0xF410, 0xFAC2,
 239     0xB63F, 0xB8ED, 0xAB9B, 0xA549, 0x8D77, 0x83A5, 0x90D3, 0x9E01,
 240     0xC0AF, 0xCE7D, 0xDD0B, 0xD3D9, 0xFBE7, 0xF535, 0xE643, 0xE891,
 241     0x5B1F, 0x55CD, 0x46BB, 0x4869, 0x6057, 0x6E85, 0x7DF3, 0x7321,
 242     0x2D8F, 0x235D, 0x302B, 0x3EF9, 0x16C7, 0x1815, 0x0B63, 0x05B1
 243 };
 244
 245 /* This table was compiled using the polynom: 0x3D65 */
 246 static const unsigned crc16_precompiled_3D65_reverse[] =
 247 {
 248     0x0000, 0x365E, 0x6CBC, 0x5AE2, 0xD978, 0xEF26, 0xB5C4, 0x839A,
 249     0xFF89, 0xC9D7, 0x9335, 0xA56B, 0x26F1, 0x10AF, 0x4A4D, 0x7C13,
 250     0xB26B, 0x8435, 0xDED7, 0xE889, 0x6B13, 0x5D4D, 0x07AF, 0x31F1,
 251     0x4DE2, 0x7BBC, 0x215E, 0x1700, 0x949A, 0xA2C4, 0xF826, 0xCE78,
 252     0x29AF, 0x1FF1, 0x4513, 0x734D, 0xF0D7, 0xC689, 0x9C6B, 0xAA35,
 253     0xD626, 0xE078, 0xBA9A, 0x8CC4, 0x0F5E, 0x3900, 0x63E2, 0x55BC,
 254     0x9BC4, 0xAD9A, 0xF778, 0xC126, 0x42BC, 0x74E2, 0x2E00, 0x185E,
 255     0x644D, 0x5213, 0x08F1, 0x3EAF, 0xBD35, 0x8B6B, 0xD189, 0xE7D7,
 256     0x535E, 0x6500, 0x3FE2, 0x09BC, 0x8A26, 0xBC78, 0xE69A, 0xD0C4,
 257     0xACD7, 0x9A89, 0xC06B, 0xF635, 0x75AF, 0x43F1, 0x1913, 0x2F4D,
 258     0xE135, 0xD76B, 0x8D89, 0xBBD7, 0x384D, 0x0E13, 0x54F1, 0x62AF,
 259     0x1EBC, 0x28E2, 0x7200, 0x445E, 0xC7C4, 0xF19A, 0xAB78, 0x9D26,
 260     0x7AF1, 0x4CAF, 0x164D, 0x2013, 0xA389, 0x95D7, 0xCF35, 0xF96B,
 261     0x8578, 0xB326, 0xE9C4, 0xDF9A, 0x5C00, 0x6A5E, 0x30BC, 0x06E2,
 262     0xC89A, 0xFEC4, 0xA426, 0x9278, 0x11E2, 0x27BC, 0x7D5E, 0x4B00,
 263     0x3713, 0x014D, 0x5BAF, 0x6DF1, 0xEE6B, 0xD835, 0x82D7, 0xB489,
 264     0xA6BC, 0x90E2, 0xCA00, 0xFC5E, 0x7FC4, 0x499A, 0x1378, 0x2526,
 265     0x5935, 0x6F6B, 0x3589, 0x03D7, 0x804D, 0xB613, 0xECF1, 0xDAAF,
 266     0x14D7, 0x2289, 0x786B, 0x4E35, 0xCDAF, 0xFBF1, 0xA113, 0x974D,
 267     0xEB5E, 0xDD00, 0x87E2, 0xB1BC, 0x3226, 0x0478, 0x5E9A, 0x68C4,
 268     0x8F13, 0xB94D, 0xE3AF, 0xD5F1, 0x566B, 0x6035, 0x3AD7, 0x0C89,
 269     0x709A, 0x46C4, 0x1C26, 0x2A78, 0xA9E2, 0x9FBC, 0xC55E, 0xF300,
 270     0x3D78, 0x0B26, 0x51C4, 0x679A, 0xE400, 0xD25E, 0x88BC, 0xBEE2,
 271     0xC2F1, 0xF4AF, 0xAE4D, 0x9813, 0x1B89, 0x2DD7, 0x7735, 0x416B,
 272     0xF5E2, 0xC3BC, 0x995E, 0xAF00, 0x2C9A, 0x1AC4, 0x4026, 0x7678,
 273     0x0A6B, 0x3C35, 0x66D7, 0x5089, 0xD313, 0xE54D, 0xBFAF, 0x89F1,
 274     0x4789, 0x71D7, 0x2B35, 0x1D6B, 0x9EF1, 0xA8AF, 0xF24D, 0xC413,
 275     0xB800, 0x8E5E, 0xD4BC, 0xE2E2, 0x6178, 0x5726, 0x0DC4, 0x3B9A,
 276     0xDC4D, 0xEA13, 0xB0F1, 0x86AF, 0x0535, 0x336B, 0x6989, 0x5FD7,
 277     0x23C4, 0x159A, 0x4F78, 0x7926, 0xFABC, 0xCCE2, 0x9600, 0xA05E,
 278     0x6E26, 0x5878, 0x029A, 0x34C4, 0xB75E, 0x8100, 0xDBE2, 0xEDBC,
 279     0x91AF, 0xA7F1, 0xFD13, 0xCB4D, 0x48D7, 0x7E89, 0x246B, 0x1235
 280 };
 281
 282 /* This table was compiled using the polynom: 0x080F */
 283 static const unsigned crc16_precompiled_080F[] =
 284 {
 285     0x0000, 0x080F, 0x101E, 0x1811, 0x203C, 0x2833, 0x3022, 0x382D,
 286     0x4078, 0x4877, 0x5066, 0x5869, 0x6044, 0x684B, 0x705A, 0x7855,
 287     0x80F0, 0x88FF, 0x90EE, 0x98E1, 0xA0CC, 0xA8C3, 0xB0D2, 0xB8DD,
 288     0xC088, 0xC887, 0xD096, 0xD899, 0xE0B4, 0xE8BB, 0xF0AA, 0xF8A5,
 289     0x09EF, 0x01E0, 0x19F1, 0x11FE, 0x29D3, 0x21DC, 0x39CD, 0x31C2,
 290     0x4997, 0x4198, 0x5989, 0x5186, 0x69AB, 0x61A4, 0x79B5, 0x71BA,
 291     0x891F, 0x8110, 0x9901, 0x910E, 0xA923, 0xA12C, 0xB93D, 0xB132,
 292     0xC967, 0xC168, 0xD979, 0xD176, 0xE95B, 0xE154, 0xF945, 0xF14A,
 293     0x13DE, 0x1BD1, 0x03C0, 0x0BCF, 0x33E2, 0x3BED, 0x23FC, 0x2BF3,
 294     0x53A6, 0x5BA9, 0x43B8, 0x4BB7, 0x739A, 0x7B95, 0x6384, 0x6B8B,
 295     0x932E, 0x9B21, 0x8330, 0x8B3F, 0xB312, 0xBB1D, 0xA30C, 0xAB03,
 296     0xD356, 0xDB59, 0xC348, 0xCB47, 0xF36A, 0xFB65, 0xE374, 0xEB7B,
 297     0x1A31, 0x123E, 0x0A2F, 0x0220, 0x3A0D, 0x3202, 0x2A13, 0x221C,
 298     0x5A49, 0x5246, 0x4A57, 0x4258, 0x7A75, 0x727A, 0x6A6B, 0x6264,
 299     0x9AC1, 0x92CE, 0x8ADF, 0x82D0, 0xBAFD, 0xB2F2, 0xAAE3, 0xA2EC,
 300     0xDAB9, 0xD2B6, 0xCAA7, 0xC2A8, 0xFA85, 0xF28A, 0xEA9B, 0xE294,
 301     0x27BC, 0x2FB3, 0x37A2, 0x3FAD, 0x0780, 0x0F8F, 0x179E, 0x1F91,
 302     0x67C4, 0x6FCB, 0x77DA, 0x7FD5, 0x47F8, 0x4FF7, 0x57E6, 0x5FE9,
 303     0xA74C, 0xAF43, 0xB752, 0xBF5D, 0x8770, 0x8F7F, 0x976E, 0x9F61,
 304     0xE734, 0xEF3B, 0xF72A, 0xFF25, 0xC708, 0xCF07, 0xD716, 0xDF19,
 305     0x2E53, 0x265C, 0x3E4D, 0x3642, 0x0E6F, 0x0660, 0x1E71, 0x167E,
 306     0x6E2B, 0x6624, 0x7E35, 0x763A, 0x4E17, 0x4618, 0x5E09, 0x5606,
 307     0xAEA3, 0xA6AC, 0xBEBD, 0xB6B2, 0x8E9F, 0x8690, 0x9E81, 0x968E,
 308     0xEEDB, 0xE6D4, 0xFEC5, 0xF6CA, 0xCEE7, 0xC6E8, 0xDEF9, 0xD6F6,
 309     0x3462, 0x3C6D, 0x247C, 0x2C73, 0x145E, 0x1C51, 0x0440, 0x0C4F,
 310     0x741A, 0x7C15, 0x6404, 0x6C0B, 0x5426, 0x5C29, 0x4438, 0x4C37,
 311     0xB492, 0xBC9D, 0xA48C, 0xAC83, 0x94AE, 0x9CA1, 0x84B0, 0x8CBF,
 312     0xF4EA, 0xFCE5, 0xE4F4, 0xECFB, 0xD4D6, 0xDCD9, 0xC4C8, 0xCCC7,
 313     0x3D8D, 0x3582, 0x2D93, 0x259C, 0x1DB1, 0x15BE, 0x0DAF, 0x05A0,
 314     0x7DF5, 0x75FA, 0x6DEB, 0x65E4, 0x5DC9, 0x55C6, 0x4DD7, 0x45D8,
 315     0xBD7D, 0xB572, 0xAD63, 0xA56C, 0x9D41, 0x954E, 0x8D5F, 0x8550,
 316     0xFD05, 0xF50A, 0xED1B, 0xE514, 0xDD39, 0xD536, 0xCD27, 0xC528
 317 };
 318
 319 /**
 320  * Generated on Fri Jul 19 17:16:42 2019
 321  * by pycrc v0.9.2, https://pycrc.org
 322  * using the configuration:
 323  *  - Width         = 16
 324  *  - Poly          = 0x8005
 325  *  - XorIn         = 0xffff
 326  *  - ReflectIn     = True
 327  *  - XorOut        = 0xffff
 328  *  - ReflectOut    = True
 329  *  - Algorithm     = table-driven
 330  */
 331 static const unsigned crc16_usb_table[] = {
 332     0x0000, 0xc0c1, 0xc181, 0x0140, 0xc301, 0x03c0, 0x0280, 0xc241,
 333     0xc601, 0x06c0, 0x0780, 0xc741, 0x0500, 0xc5c1, 0xc481, 0x0440,
 334     0xcc01, 0x0cc0, 0x0d80, 0xcd41, 0x0f00, 0xcfc1, 0xce81, 0x0e40,
 335     0x0a00, 0xcac1, 0xcb81, 0x0b40, 0xc901, 0x09c0, 0x0880, 0xc841,
 336     0xd801, 0x18c0, 0x1980, 0xd941, 0x1b00, 0xdbc1, 0xda81, 0x1a40,
 337     0x1e00, 0xdec1, 0xdf81, 0x1f40, 0xdd01, 0x1dc0, 0x1c80, 0xdc41,
 338     0x1400, 0xd4c1, 0xd581, 0x1540, 0xd701, 0x17c0, 0x1680, 0xd641,
 339     0xd201, 0x12c0, 0x1380, 0xd341, 0x1100, 0xd1c1, 0xd081, 0x1040,
 340     0xf001, 0x30c0, 0x3180, 0xf141, 0x3300, 0xf3c1, 0xf281, 0x3240,
 341     0x3600, 0xf6c1, 0xf781, 0x3740, 0xf501, 0x35c0, 0x3480, 0xf441,
 342     0x3c00, 0xfcc1, 0xfd81, 0x3d40, 0xff01, 0x3fc0, 0x3e80, 0xfe41,
 343     0xfa01, 0x3ac0, 0x3b80, 0xfb41, 0x3900, 0xf9c1, 0xf881, 0x3840,
 344     0x2800, 0xe8c1, 0xe981, 0x2940, 0xeb01, 0x2bc0, 0x2a80, 0xea41,
 345     0xee01, 0x2ec0, 0x2f80, 0xef41, 0x2d00, 0xedc1, 0xec81, 0x2c40,
 346     0xe401, 0x24c0, 0x2580, 0xe541, 0x2700, 0xe7c1, 0xe681, 0x2640,
 347     0x2200, 0xe2c1, 0xe381, 0x2340, 0xe101, 0x21c0, 0x2080, 0xe041,
 348     0xa001, 0x60c0, 0x6180, 0xa141, 0x6300, 0xa3c1, 0xa281, 0x6240,
 349     0x6600, 0xa6c1, 0xa781, 0x6740, 0xa501, 0x65c0, 0x6480, 0xa441,
 350     0x6c00, 0xacc1, 0xad81, 0x6d40, 0xaf01, 0x6fc0, 0x6e80, 0xae41,
 351     0xaa01, 0x6ac0, 0x6b80, 0xab41, 0x6900, 0xa9c1, 0xa881, 0x6840,
 352     0x7800, 0xb8c1, 0xb981, 0x7940, 0xbb01, 0x7bc0, 0x7a80, 0xba41,
 353     0xbe01, 0x7ec0, 0x7f80, 0xbf41, 0x7d00, 0xbdc1, 0xbc81, 0x7c40,
 354     0xb401, 0x74c0, 0x7580, 0xb541, 0x7700, 0xb7c1, 0xb681, 0x7640,
 355     0x7200, 0xb2c1, 0xb381, 0x7340, 0xb101, 0x71c0, 0x7080, 0xb041,
 356     0x5000, 0x90c1, 0x9181, 0x5140, 0x9301, 0x53c0, 0x5280, 0x9241,
 357     0x9601, 0x56c0, 0x5780, 0x9741, 0x5500, 0x95c1, 0x9481, 0x5440,
 358     0x9c01, 0x5cc0, 0x5d80, 0x9d41, 0x5f00, 0x9fc1, 0x9e81, 0x5e40,
 359     0x5a00, 0x9ac1, 0x9b81, 0x5b40, 0x9901, 0x59c0, 0x5880, 0x9841,
 360     0x8801, 0x48c0, 0x4980, 0x8941, 0x4b00, 0x8bc1, 0x8a81, 0x4a40,
 361     0x4e00, 0x8ec1, 0x8f81, 0x4f40, 0x8d01, 0x4dc0, 0x4c80, 0x8c41,
 362     0x4400, 0x84c1, 0x8581, 0x4540, 0x8701, 0x47c0, 0x4680, 0x8641,
 363     0x8201, 0x42c0, 0x4380, 0x8341, 0x4100, 0x81c1, 0x8081, 0x4040
 364 };
 365
 366 static const uint16_t crc16_ccitt_start = 0xFFFF;
 367 static const uint16_t crc16_ccitt_xorout = 0xFFFF;
 368
 369 static const uint16_t crc16_usb_start = 0xFFFF;
 370 static const uint16_t crc16_usb_xorout = 0xFFFF;
 371
 372 /* two types of crcs are possible: unreflected (bits shift left) and
 373  * reflected (bits shift right).
 374  */
 375 static uint16_t crc16_unreflected(const uint8_t *buf, unsigned len,
 376                                  uint16_t crc_in, const unsigned table[])
 377 {
 378     /* we use uints, rather than uint16s, as they are likely to be
 379        faster. We just ignore the top 16 bits and let them do what they want.
 380     */
 381     unsigned crc16 = (unsigned)crc_in;
 382
 383     while( len-- != 0 )
 384         crc16 = table[((crc16 >> 8) ^ *buf++) & 0xff] ^ (crc16 << 8);
 385
 386     return (uint16_t)crc16;
 387 }
 388
 389 static uint16_t crc16_reflected(const uint8_t *buf, unsigned len,
 390                                 uint16_t crc_in, const unsigned table[])
 391 {
 392     /* we use uints, rather than uint16s, as they are likely to be
 393        faster. We just ignore the top 16 bits and let them do what they want.
 394        XXX - does any time saved not zero-extending uint16_t's to 32 bits
 395        into a register outweigh any increased cache footprint from the
 396        larger CRC table? */
 397     unsigned crc16 = (unsigned)crc_in;
 398
 399     while( len-- != 0 )
 400        crc16 = table[(crc16 ^ *buf++) & 0xff] ^ (crc16 >> 8);
 401
 402     return (uint16_t)crc16;
 403 }
 404
 405 uint16_t crc16_ccitt(const uint8_t *buf, unsigned len)
 406 {
 407     return crc16_reflected(buf,len,crc16_ccitt_start,crc16_ccitt_table_reverse)
 408        ^ crc16_ccitt_xorout;
 409 }
 410
 411 uint16_t crc16_x25_ccitt_seed(const uint8_t *buf, unsigned len, uint16_t seed)
 412 {
 413     return crc16_unreflected(buf,len,seed,crc16_ccitt_table);
 414 }
 415
 416 uint16_t crc16_ccitt_seed(const uint8_t *buf, unsigned len, uint16_t seed)
 417 {
 418     return crc16_reflected(buf,len,seed,crc16_ccitt_table_reverse)
 419        ^ crc16_ccitt_xorout;
 420 }
 421
 422 /* ISO14443-3, section 6.2.4: For ISO14443-A, the polynomial 0x1021 is
 423    used, the initial register value shall be 0x6363, the final register
 424    value is not XORed with anything. */
 425 uint16_t crc16_iso14443a(const uint8_t *buf, unsigned len)
 426 {
 427     return crc16_reflected(buf,len, 0x6363 ,crc16_ccitt_table_reverse);
 428 }
 429
 430 uint16_t crc16_usb(const uint8_t *buf, unsigned len)
 431 {
 432     return crc16_reflected(buf, len, crc16_usb_start, crc16_usb_table)
 433         ^ crc16_usb_xorout;
 434 }
 435
 436 uint16_t crc16_0x5935(const uint8_t *buf, uint32_t len, uint16_t seed)
 437 {
 438     return crc16_unreflected(buf, len, seed, crc16_precompiled_5935);
 439 }
 440
 441 uint16_t crc16_0x755B(const uint8_t *buf, uint32_t len, uint16_t seed)
 442 {
 443     return crc16_unreflected(buf, len, seed, crc16_precompiled_755B);
 444 }
 445
 446 uint16_t crc16_0x9949_seed(const uint8_t *buf, unsigned len, uint16_t seed)
 447 {
 448     return crc16_reflected(buf, len, seed, crc16_precompiled_9949_reverse);
 449 }
 450
 451 uint16_t crc16_0x3D65_seed(const uint8_t *buf, unsigned len, uint16_t seed)
 452 {
 453     return crc16_reflected(buf, len, seed, crc16_precompiled_3D65_reverse);
 454 }
 455
 456 uint16_t crc16_0x080F_seed(const uint8_t *buf, unsigned len, uint16_t seed)
 457 {
 458     uint16_t crc = seed;
 459
 460     if (len > 0)
 461     {
 462         while (len-- > 0)
 463         {
 464             uint8_t data = *buf++;
 465             crc = crc16_precompiled_080F[((crc >> 8) ^ data)] ^ (crc << 8);
 466         }
 467     }
 468
 469     return crc;
 470 }
 471
 472 /*
 473  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 474  *
 475  * Local variables:
 476  * c-basic-offset: 4
 477  * tab-width: 8
 478  * indent-tabs-mode: nil
 479  * End:
 480  *
 481  * vi: set shiftwidth=4 tabstop=8 expandtab:
 482  * :indentSize=4:tabSize=8:noTabs=true:
 483  */