com_crc16.c

   1 /*
   2 Copyright (C) 1996-1997 Id Software, Inc.
   3
   4 This program is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU General Public License
   6 as published by the Free Software Foundation; either version 2
   7 of the License, or (at your option) any later version.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  12
  13 See the GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program; if not, write to the Free Software
  17 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  18
  19 */
  20 // com_crc16.c
  21
  22 #include "darkplaces.h"
  23
  24 /*
  25 ============================================================================
  26
  27                                         CRC FUNCTIONS
  28
  29 ============================================================================
  30 */
  31
  32 // this is a 16 bit, non-reflected CRC using the polynomial 0x1021
  33 // and the initial and final xor values shown below...  in other words, the
  34 // CCITT standard CRC used by XMODEM
  35
  36 #define CRC_INIT_VALUE  0xffff
  37 #define CRC_XOR_VALUE   0x0000
  38
  39 static unsigned short crctable[256] =
  40 {
  41         0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
  42         0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
  43         0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
  44         0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
  45         0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
  46         0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
  47         0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
  48         0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
  49         0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
  50         0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
  51         0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
  52         0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
  53         0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
  54         0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
  55         0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
  56         0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
  57         0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
  58         0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
  59         0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
  60         0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
  61         0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
  62         0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
  63         0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
  64         0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
  65         0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
  66         0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
  67         0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
  68         0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
  69         0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
  70         0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
  71         0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
  72         0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
  73 };
  74
  75 unsigned short CRC_Block(const unsigned char *data, size_t size)
  76 {
  77         unsigned short crc = CRC_INIT_VALUE;
  78         while (size--)
  79                 crc = (crc << 8) ^ crctable[(crc >> 8) ^ (*data++)];
  80         return crc ^ CRC_XOR_VALUE;
  81 }
  82
  83 unsigned short CRC_Block_CaseInsensitive(const unsigned char *data, size_t size)
  84 {
  85         unsigned short crc = CRC_INIT_VALUE;
  86         while (size--)
  87                 crc = (crc << 8) ^ crctable[(crc >> 8) ^ (tolower(*data++))];
  88         return crc ^ CRC_XOR_VALUE;
  89 }
  90
  91 // QuakeWorld
  92 static unsigned char chktbl[1024 + 4] =
  93 {
  94         0x78,0xd2,0x94,0xe3,0x41,0xec,0xd6,0xd5,0xcb,0xfc,0xdb,0x8a,0x4b,0xcc,0x85,0x01,
  95         0x23,0xd2,0xe5,0xf2,0x29,0xa7,0x45,0x94,0x4a,0x62,0xe3,0xa5,0x6f,0x3f,0xe1,0x7a,
  96         0x64,0xed,0x5c,0x99,0x29,0x87,0xa8,0x78,0x59,0x0d,0xaa,0x0f,0x25,0x0a,0x5c,0x58,
  97         0xfb,0x00,0xa7,0xa8,0x8a,0x1d,0x86,0x80,0xc5,0x1f,0xd2,0x28,0x69,0x71,0x58,0xc3,
  98         0x51,0x90,0xe1,0xf8,0x6a,0xf3,0x8f,0xb0,0x68,0xdf,0x95,0x40,0x5c,0xe4,0x24,0x6b,
  99         0x29,0x19,0x71,0x3f,0x42,0x63,0x6c,0x48,0xe7,0xad,0xa8,0x4b,0x91,0x8f,0x42,0x36,
 100         0x34,0xe7,0x32,0x55,0x59,0x2d,0x36,0x38,0x38,0x59,0x9b,0x08,0x16,0x4d,0x8d,0xf8,
 101         0x0a,0xa4,0x52,0x01,0xbb,0x52,0xa9,0xfd,0x40,0x18,0x97,0x37,0xff,0xc9,0x82,0x27,
 102         0xb2,0x64,0x60,0xce,0x00,0xd9,0x04,0xf0,0x9e,0x99,0xbd,0xce,0x8f,0x90,0x4a,0xdd,
 103         0xe1,0xec,0x19,0x14,0xb1,0xfb,0xca,0x1e,0x98,0x0f,0xd4,0xcb,0x80,0xd6,0x05,0x63,
 104         0xfd,0xa0,0x74,0xa6,0x86,0xf6,0x19,0x98,0x76,0x27,0x68,0xf7,0xe9,0x09,0x9a,0xf2,
 105         0x2e,0x42,0xe1,0xbe,0x64,0x48,0x2a,0x74,0x30,0xbb,0x07,0xcc,0x1f,0xd4,0x91,0x9d,
 106         0xac,0x55,0x53,0x25,0xb9,0x64,0xf7,0x58,0x4c,0x34,0x16,0xbc,0xf6,0x12,0x2b,0x65,
 107         0x68,0x25,0x2e,0x29,0x1f,0xbb,0xb9,0xee,0x6d,0x0c,0x8e,0xbb,0xd2,0x5f,0x1d,0x8f,
 108         0xc1,0x39,0xf9,0x8d,0xc0,0x39,0x75,0xcf,0x25,0x17,0xbe,0x96,0xaf,0x98,0x9f,0x5f,
 109         0x65,0x15,0xc4,0x62,0xf8,0x55,0xfc,0xab,0x54,0xcf,0xdc,0x14,0x06,0xc8,0xfc,0x42,
 110         0xd3,0xf0,0xad,0x10,0x08,0xcd,0xd4,0x11,0xbb,0xca,0x67,0xc6,0x48,0x5f,0x9d,0x59,
 111         0xe3,0xe8,0x53,0x67,0x27,0x2d,0x34,0x9e,0x9e,0x24,0x29,0xdb,0x69,0x99,0x86,0xf9,
 112         0x20,0xb5,0xbb,0x5b,0xb0,0xf9,0xc3,0x67,0xad,0x1c,0x9c,0xf7,0xcc,0xef,0xce,0x69,
 113         0xe0,0x26,0x8f,0x79,0xbd,0xca,0x10,0x17,0xda,0xa9,0x88,0x57,0x9b,0x15,0x24,0xba,
 114         0x84,0xd0,0xeb,0x4d,0x14,0xf5,0xfc,0xe6,0x51,0x6c,0x6f,0x64,0x6b,0x73,0xec,0x85,
 115         0xf1,0x6f,0xe1,0x67,0x25,0x10,0x77,0x32,0x9e,0x85,0x6e,0x69,0xb1,0x83,0x00,0xe4,
 116         0x13,0xa4,0x45,0x34,0x3b,0x40,0xff,0x41,0x82,0x89,0x79,0x57,0xfd,0xd2,0x8e,0xe8,
 117         0xfc,0x1d,0x19,0x21,0x12,0x00,0xd7,0x66,0xe5,0xc7,0x10,0x1d,0xcb,0x75,0xe8,0xfa,
 118         0xb6,0xee,0x7b,0x2f,0x1a,0x25,0x24,0xb9,0x9f,0x1d,0x78,0xfb,0x84,0xd0,0x17,0x05,
 119         0x71,0xb3,0xc8,0x18,0xff,0x62,0xee,0xed,0x53,0xab,0x78,0xd3,0x65,0x2d,0xbb,0xc7,
 120         0xc1,0xe7,0x70,0xa2,0x43,0x2c,0x7c,0xc7,0x16,0x04,0xd2,0x45,0xd5,0x6b,0x6c,0x7a,
 121         0x5e,0xa1,0x50,0x2e,0x31,0x5b,0xcc,0xe8,0x65,0x8b,0x16,0x85,0xbf,0x82,0x83,0xfb,
 122         0xde,0x9f,0x36,0x48,0x32,0x79,0xd6,0x9b,0xfb,0x52,0x45,0xbf,0x43,0xf7,0x0b,0x0b,
 123         0x19,0x19,0x31,0xc3,0x85,0xec,0x1d,0x8c,0x20,0xf0,0x3a,0xfa,0x80,0x4d,0x2c,0x7d,
 124         0xac,0x60,0x09,0xc0,0x40,0xee,0xb9,0xeb,0x13,0x5b,0xe8,0x2b,0xb1,0x20,0xf0,0xce,
 125         0x4c,0xbd,0xc6,0x04,0x86,0x70,0xc6,0x33,0xc3,0x15,0x0f,0x65,0x19,0xfd,0xc2,0xd3,
 126
 127         // map checksum goes here
 128         0x00,0x00,0x00,0x00
 129 };
 130
 131 // QuakeWorld
 132 unsigned char COM_BlockSequenceCRCByteQW(unsigned char *base, int length, int sequence)
 133 {
 134         unsigned char *p;
 135         unsigned char chkb[60 + 4];
 136
 137         p = chktbl + (sequence % (sizeof(chktbl) - 8));
 138
 139         if (length > 60)
 140                 length = 60;
 141         memcpy(chkb, base, length);
 142
 143         chkb[length] = (sequence & 0xff) ^ p[0];
 144         chkb[length+1] = p[1];
 145         chkb[length+2] = ((sequence>>8) & 0xff) ^ p[2];
 146         chkb[length+3] = p[3];
 147
 148         return CRC_Block(chkb, length + 4) & 0xff;
 149 }