//=======================================================================
//			Copyright XashXT Group 2007 ©
//			crclib.c - generate crc stuff
//=======================================================================

#include "launch.h"

/*
=============================================================================
this is a 16 bit, non-reflected CRC using the polynomial 0x1021
and the initial and final xor values shown below...  in other words, the
CCITT standard CRC used by XMODEM
=============================================================================
*/
#define NUM_BYTES		256
#define CRC_INIT_VALUE	0xffff
#define CRC_XOR_VALUE	0x0000
#define CRC32_INIT_VALUE	0xFFFFFFFFUL
#define CRC32_XOR_VALUE	0xFFFFFFFFUL

static const CRC16_t crctable[NUM_BYTES] =
{
0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
};

static const CRC32_t crc32table[NUM_BYTES] =
{
0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
};

static byte chktbl[1024] = 
{
0x84, 0x47, 0x51, 0xc1, 0x93, 0x22, 0x21, 0x24, 0x2f, 0x66, 0x60, 0x4d, 0xb0, 0x7c, 0xda,
0x88, 0x54, 0x15, 0x2b, 0xc6, 0x6c, 0x89, 0xc5, 0x9d, 0x48, 0xee, 0xe6, 0x8a, 0xb5, 0xf4,
0xcb, 0xfb, 0xf1, 0x0c, 0x2e, 0xa0, 0xd7, 0xc9, 0x1f, 0xd6, 0x06, 0x9a, 0x09, 0x41, 0x54,
0x67, 0x46, 0xc7, 0x74, 0xe3, 0xc8, 0xb6, 0x5d, 0xa6, 0x36, 0xc4, 0xab, 0x2c, 0x7e, 0x85,
0xa8, 0xa4, 0xa6, 0x4d, 0x96, 0x19, 0x19, 0x9a, 0xcc, 0xd8, 0xac, 0x39, 0x5e, 0x3c, 0xf2,
0xf5, 0x5a, 0x72, 0xe5, 0xa9, 0xd1, 0xb3, 0x23, 0x82, 0x6f, 0x29, 0xcb, 0xd1, 0xcc, 0x71,
0xfb, 0xea, 0x92, 0xeb, 0x1c, 0xca, 0x4c, 0x70, 0xfe, 0x4d, 0xc9, 0x67, 0x43, 0x47, 0x94,
0xb9, 0x47, 0xbc, 0x3f, 0x01, 0xab, 0x7b, 0xa6, 0xe2, 0x76, 0xef, 0x5a, 0x7a, 0x29, 0x0b,
0x51, 0x54, 0x67, 0xd8, 0x1c, 0x14, 0x3e, 0x29, 0xec, 0xe9, 0x2d, 0x48, 0x67, 0xff, 0xed,
0x54, 0x4f, 0x48, 0xc0, 0xaa, 0x61, 0xf7, 0x78, 0x12, 0x03, 0x7a, 0x9e, 0x8b, 0xcf, 0x83,
0x7b, 0xae, 0xca, 0x7b, 0xd9, 0xe9, 0x53, 0x2a, 0xeb, 0xd2, 0xd8, 0xcd, 0xa3, 0x10, 0x25,
0x78, 0x5a, 0xb5, 0x23, 0x06, 0x93, 0xb7, 0x84, 0xd2, 0xbd, 0x96, 0x75, 0xa5, 0x5e, 0xcf,
0x4e, 0xe9, 0x50, 0xa1, 0xe6, 0x9d, 0xb1, 0xe3, 0x85, 0x66, 0x28, 0x4e, 0x43, 0xdc, 0x6e,
0xbb, 0x33, 0x9e, 0xf3, 0x0d, 0x00, 0xc1, 0xcf, 0x67, 0x34, 0x06, 0x7c, 0x71, 0xe3, 0x63,
0xb7, 0xb7, 0xdf, 0x92, 0xc4, 0xc2, 0x25, 0x5c, 0xff, 0xc3, 0x6e, 0xfc, 0xaa, 0x1e, 0x2a,
0x48, 0x11, 0x1c, 0x36, 0x68, 0x78, 0x86, 0x79, 0x30, 0xc3, 0xd6, 0xde, 0xbc, 0x3a, 0x2a,
0x6d, 0x1e, 0x46, 0xdd, 0xe0, 0x80, 0x1e, 0x44, 0x3b, 0x6f, 0xaf, 0x31, 0xda, 0xa2, 0xbd,
0x77, 0x06, 0x56, 0xc0, 0xb7, 0x92, 0x4b, 0x37, 0xc0, 0xfc, 0xc2, 0xd5, 0xfb, 0xa8, 0xda,
0xf5, 0x57, 0xa8, 0x18, 0xc0, 0xdf, 0xe7, 0xaa, 0x2a, 0xe0, 0x7c, 0x6f, 0x77, 0xb1, 0x26,
0xba, 0xf9, 0x2e, 0x1d, 0x16, 0xcb, 0xb8, 0xa2, 0x44, 0xd5, 0x2f, 0x1a, 0x79, 0x74, 0x87,
0x4b, 0x00, 0xc9, 0x4a, 0x3a, 0x65, 0x8f, 0xe6, 0x5d, 0xe5, 0x0a, 0x77, 0xd8, 0x1a, 0x14,
0x41, 0x75, 0xb1, 0xe2, 0x50, 0x2c, 0x93, 0x38, 0x2b, 0x6d, 0xf3, 0xf6, 0xdb, 0x1f, 0xcd,
0xff, 0x14, 0x70, 0xe7, 0x16, 0xe8, 0x3d, 0xf0, 0xe3, 0xbc, 0x5e, 0xb6, 0x3f, 0xcc, 0x81,
0x24, 0x67, 0xf3, 0x97, 0x3b, 0xfe, 0x3a, 0x96, 0x85, 0xdf, 0xe4, 0x6e, 0x3c, 0x85, 0x05,
0x0e, 0xa3, 0x2b, 0x07, 0xc8, 0xbf, 0xe5, 0x13, 0x82, 0x62, 0x08, 0x61, 0x69, 0x4b, 0x47,
0x62, 0x73, 0x44, 0x64, 0x8e, 0xe2, 0x91, 0xa6, 0x9a, 0xb7, 0xe9, 0x04, 0xb6, 0x54, 0x0c,
0xc5, 0xa9, 0x47, 0xa6, 0xc9, 0x08, 0xfe, 0x4e, 0xa6, 0xcc, 0x8a, 0x5b, 0x90, 0x6f, 0x2b,
0x3f, 0xb6, 0x0a, 0x96, 0xc0, 0x78, 0x58, 0x3c, 0x76, 0x6d, 0x94, 0x1a, 0xe4, 0x4e, 0xb8,
0x38, 0xbb, 0xf5, 0xeb, 0x29, 0xd8, 0xb0, 0xf3, 0x15, 0x1e, 0x99, 0x96, 0x3c, 0x5d, 0x63,
0xd5, 0xb1, 0xad, 0x52, 0xb8, 0x55, 0x70, 0x75, 0x3e, 0x1a, 0xd5, 0xda, 0xf6, 0x7a, 0x48,
0x7d, 0x44, 0x41, 0xf9, 0x11, 0xce, 0xd7, 0xca, 0xa5, 0x3d, 0x7a, 0x79, 0x7e, 0x7d, 0x25,
0x1b, 0x77, 0xbc, 0xf7, 0xc7, 0x0f, 0x84, 0x95, 0x10, 0x92, 0x67, 0x15, 0x11, 0x5a, 0x5e,
0x41, 0x66, 0x0f, 0x38, 0x03, 0xb2, 0xf1, 0x5d, 0xf8, 0xab, 0xc0, 0x02, 0x76, 0x84, 0x28,
0xf4, 0x9d, 0x56, 0x46, 0x60, 0x20, 0xdb, 0x68, 0xa7, 0xbb, 0xee, 0xac, 0x15, 0x01, 0x2f,
0x20, 0x09, 0xdb, 0xc0, 0x16, 0xa1, 0x89, 0xf9, 0x94, 0x59, 0x00, 0xc1, 0x76, 0xbf, 0xc1,
0x4d, 0x5d, 0x2d, 0xa9, 0x85, 0x2c, 0xd6, 0xd3, 0x14, 0xcc, 0x02, 0xc3, 0xc2, 0xfa, 0x6b,
0xb7, 0xa6, 0xef, 0xdd, 0x12, 0x26, 0xa4, 0x63, 0xe3, 0x62, 0xbd, 0x56, 0x8a, 0x52, 0x2b,
0xb9, 0xdf, 0x09, 0xbc, 0x0e, 0x97, 0xa9, 0xb0, 0x82, 0x46, 0x08, 0xd5, 0x1a, 0x8e, 0x1b,
0xa7, 0x90, 0x98, 0xb9, 0xbb, 0x3c, 0x17, 0x9a, 0xf2, 0x82, 0xba, 0x64, 0x0a, 0x7f, 0xca,
0x5a, 0x8c, 0x7c, 0xd3, 0x79, 0x09, 0x5b, 0x26, 0xbb, 0xbd, 0x25, 0xdf, 0x3d, 0x6f, 0x9a,
0x8f, 0xee, 0x21, 0x66, 0xb0, 0x8d, 0x84, 0x4c, 0x91, 0x45, 0xd4, 0x77, 0x4f, 0xb3, 0x8c,
0xbc, 0xa8, 0x99, 0xaa, 0x19, 0x53, 0x7c, 0x02, 0x87, 0xbb, 0x0b, 0x7c, 0x1a, 0x2d, 0xdf,
0x48, 0x44, 0x06, 0xd6, 0x7d, 0x0c, 0x2d, 0x35, 0x76, 0xae, 0xc4, 0x5f, 0x71, 0x85, 0x97,
0xc4, 0x3d, 0xef, 0x52, 0xbe, 0x00, 0xe4, 0xcd, 0x49, 0xd1, 0xd1, 0x1c, 0x3c, 0xd0, 0x1c,
0x42, 0xaf, 0xd4, 0xbd, 0x58, 0x34, 0x07, 0x32, 0xee, 0xb9, 0xb5, 0xea, 0xff, 0xd7, 0x8c,
0x0d, 0x2e, 0x2f, 0xaf, 0x87, 0xbb, 0xe6, 0x52, 0x71, 0x22, 0xf5, 0x25, 0x17, 0xa1, 0x82,
0x04, 0xc2, 0x4a, 0xbd, 0x57, 0xc6, 0xab, 0xc8, 0x35, 0x0c, 0x3c, 0xd9, 0xc2, 0x43, 0xdb,
0x27, 0x92, 0xcf, 0xb8, 0x25, 0x60, 0xfa, 0x21, 0x3b, 0x04, 0x52, 0xc8, 0x96, 0xba, 0x74,
0xe3, 0x67, 0x3e, 0x8e, 0x8d, 0x61, 0x90, 0x92, 0x59, 0xb6, 0x1a, 0x1c, 0x5e, 0x21, 0xc1,
0x65, 0xe5, 0xa6, 0x34, 0x05, 0x6f, 0xc5, 0x60, 0xb1, 0x83, 0xc1, 0xd5, 0xd5, 0xed, 0xd9,
0xc7, 0x11, 0x7b, 0x49, 0x7a, 0xf9, 0xf9, 0x84, 0x47, 0x9b, 0xe2, 0xa5, 0x82, 0xe0, 0xc2,
0x88, 0xd0, 0xb2, 0x58, 0x88, 0x7f, 0x45, 0x09, 0x67, 0x74, 0x61, 0xbf, 0xe6, 0x40, 0xe2,
0x9d, 0xc2, 0x47, 0x05, 0x89, 0xed, 0xcb, 0xbb, 0xb7, 0x27, 0xe7, 0xdc, 0x7a, 0xfd, 0xbf,
0xa8, 0xd0, 0xaa, 0x10, 0x39, 0x3c, 0x20, 0xf0, 0xd3, 0x6e, 0xb1, 0x72, 0xf8, 0xe6, 0x0f,
0xef, 0x37, 0xe5, 0x09, 0x33, 0x5a, 0x83, 0x43, 0x80, 0x4f, 0x65, 0x2f, 0x7c, 0x8c, 0x6a,
0xa0, 0x82, 0x0c, 0xd4, 0xd4, 0xfa, 0x81, 0x60, 0x3d, 0xdf, 0x06, 0xf1, 0x5f, 0x08, 0x0d,
0x6d, 0x43, 0xf2, 0xe3, 0x11, 0x7d, 0x80, 0x32, 0xc5, 0xfb, 0xc5, 0xd9, 0x27, 0xec, 0xc6,
0x4e, 0x65, 0x27, 0x76, 0x87, 0xa6, 0xee, 0xee, 0xd7, 0x8b, 0xd1, 0xa0, 0x5c, 0xb0, 0x42,
0x13, 0x0e, 0x95, 0x4a, 0xf2, 0x06, 0xc6, 0x43, 0x33, 0xf4, 0xc7, 0xf8, 0xe7, 0x1f, 0xdd,
0xe4, 0x46, 0x4a, 0x70, 0x39, 0x6c, 0xd0, 0xed, 0xca, 0xbe, 0x60, 0x3b, 0xd1, 0x7b, 0x57,
0x48, 0xe5, 0x3a, 0x79, 0xc1, 0x69, 0x33, 0x53, 0x1b, 0x80, 0xb8, 0x91, 0x7d, 0xb4, 0xf6,
0x17, 0x1a, 0x1d, 0x5a, 0x32, 0xd6, 0xcc, 0x71, 0x29, 0x3f, 0x28, 0xbb, 0xf3, 0x5e, 0x71,
0xb8, 0x43, 0xaf, 0xf8, 0xb9, 0x64, 0xef, 0xc4, 0xa5, 0x6c, 0x08, 0x53, 0xc7, 0x00, 0x10,
0x39, 0x4f, 0xdd, 0xe4, 0xb6, 0x19, 0x27, 0xfb, 0xb8, 0xf5, 0x32, 0x73, 0xe5, 0xcb, 0x32
};

void CRC_Init( CRC16_t *crcvalue )
{
	*crcvalue = CRC_INIT_VALUE;
}

void CRC_ProcessByte( CRC16_t *crcvalue, byte data )
{
	*crcvalue = (*crcvalue << 8) ^ crctable[(*crcvalue >> 8) ^ data];
}

CRC16_t CRC_Block( byte *start, int count )
{
	CRC16_t	crc;

	CRC_Init (&crc);
	while(count--) CRC_ProcessByte( &crc, *start++ );

	return crc;
}

/*
====================
CRC_BlockSequence

For proxy protecting
====================
*/
byte CRC_BlockSequence(byte *base, int length, int sequence)
{
	int	n, x;
	CRC16_t	crc;
	byte	*p, chkb[60 + 4];

	if (sequence < 0) sequence = abs(sequence);
	p = chktbl + (sequence % (sizeof(chktbl) - 4));

	if( length > 60 ) length = 60;
	Mem_Copy( chkb, base, length );

	chkb[length] = p[0];
	chkb[length + 1] = p[1];
	chkb[length + 2] = p[2];
	chkb[length + 3] = p[3];
	length += 4;

	crc = CRC_Block(chkb, length);
	for (x = 0, n = 0; n < length; n++) x += chkb[n];
	crc = (crc ^ x) & 0xff;

	return crc;
}

void CRC32_Init( CRC32_t *pulCRC )
{
	*pulCRC = CRC32_INIT_VALUE;
}

void CRC32_Final( CRC32_t *pulCRC )
{
	*pulCRC ^= CRC32_XOR_VALUE;
}

void CRC32_ProcessByte( CRC32_t *pulCRC, byte ch )
{
	CRC32_t	ulCrc = *pulCRC;

	ulCrc ^= ch;
	ulCrc = crc32table[(byte)ulCrc] ^ (ulCrc >> 8);
	*pulCRC = ulCrc;
}

void CRC32_ProcessBuffer( CRC32_t *pulCRC, const void *pBuffer, int nBuffer )
{
	CRC32_t	ulCrc = *pulCRC;
	byte	*pb = (byte *)pBuffer;
	uint	nFront;
	int	nMain;
JustAfew:
	switch( nBuffer )
	{
	case 7: ulCrc  = crc32table[*pb++ ^ (byte)ulCrc] ^ (ulCrc >> 8);
	case 6: ulCrc  = crc32table[*pb++ ^ (byte)ulCrc] ^ (ulCrc >> 8);
	case 5: ulCrc  = crc32table[*pb++ ^ (byte)ulCrc] ^ (ulCrc >> 8);
	case 4:
		
		ulCrc ^= *(CRC32_t *)pb;	// warning, this only works on little-endian.
		ulCrc  = crc32table[(byte)ulCrc] ^ (ulCrc >> 8);
		ulCrc  = crc32table[(byte)ulCrc] ^ (ulCrc >> 8);
		ulCrc  = crc32table[(byte)ulCrc] ^ (ulCrc >> 8);
		ulCrc  = crc32table[(byte)ulCrc] ^ (ulCrc >> 8);
		*pulCRC = ulCrc;
		return;
	case 3: ulCrc  = crc32table[*pb++ ^ (byte)ulCrc] ^ (ulCrc >> 8);
	case 2: ulCrc  = crc32table[*pb++ ^ (byte)ulCrc] ^ (ulCrc >> 8);
	case 1: ulCrc  = crc32table[*pb++ ^ (byte)ulCrc] ^ (ulCrc >> 8);
	case 0: *pulCRC = ulCrc;
		return;
	}

	// We may need to do some alignment work up front, and at the end, so that
	// the main loop is aligned and only has to worry about 8 byte at a time.
	// The low-order two bits of pb and nBuffer in total control the
	// upfront work.

	nFront = ((uint)pb) & 3;
	nBuffer -= nFront;

	switch( nFront )
	{
	case 3: ulCrc  = crc32table[*pb++ ^ (byte)ulCrc] ^ (ulCrc >> 8);
	case 2: ulCrc  = crc32table[*pb++ ^ (byte)ulCrc] ^ (ulCrc >> 8);
	case 1: ulCrc  = crc32table[*pb++ ^ (byte)ulCrc] ^ (ulCrc >> 8);
	}

	nMain = nBuffer >> 3;
	while( nMain-- )
	{
		ulCrc ^= *(CRC32_t *)pb;	// warning, this only works on little-endian.
		ulCrc  = crc32table[(byte)ulCrc] ^ (ulCrc >> 8);
		ulCrc  = crc32table[(byte)ulCrc] ^ (ulCrc >> 8);
		ulCrc  = crc32table[(byte)ulCrc] ^ (ulCrc >> 8);
		ulCrc  = crc32table[(byte)ulCrc] ^ (ulCrc >> 8);
		ulCrc ^= *(CRC32_t *)(pb + 4);// warning, this only works on little-endian.
		ulCrc  = crc32table[(byte)ulCrc] ^ (ulCrc >> 8);
		ulCrc  = crc32table[(byte)ulCrc] ^ (ulCrc >> 8);
		ulCrc  = crc32table[(byte)ulCrc] ^ (ulCrc >> 8);
		ulCrc  = crc32table[(byte)ulCrc] ^ (ulCrc >> 8);
		pb += 8;
	}

	nBuffer &= 7;
	goto JustAfew;
}

/*
=============================================================================
MD4C.C - RSA Data Security, Inc., MD4 message-digest algorithm
Copyright (C) 1990-2, RSA Data Security, Inc. All rights reserved.
=============================================================================
*/
#pragma warning(disable : 4711) // selected for automatic inline expansion

typedef byte *POINTER;
typedef unsigned short int UINT2;
typedef unsigned long int UINT4;

// MD4 context
typedef struct
{
	UINT4	state[4];		// state (ABCD)
	UINT4	count[2];		// number of bits, modulo 2^64 (lsb first)
	byte	buffer[64];	// input buffer
} MD4_CTX;

void MD4Init( MD4_CTX * );
void MD4Update( MD4_CTX *, const byte *, uint);
void MD4Final (byte [16], MD4_CTX *);

#define S11	3
#define S12	7
#define S13	11
#define S14	19
#define S21	3
#define S22	5
#define S23	9
#define S24	13
#define S31	3
#define S32	9
#define S33	11
#define S34	15

static void MD4Transform (UINT4 [4], const byte [64]);
static void Encode (byte*, UINT4*, uint);
static void Decode (UINT4*, const byte*, uint);

static byte PADDING[64] = 
{
0x80, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0
};

// F, G and H are basic MD4 functions.
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (y)) | ((x) & (z)) | ((y) & (z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))

// ROTATE_LEFT rotates x left n bits.
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

// FF, GG and HH are transformations for rounds 1, 2 and 3
// Rotation is separate from addition to prevent recomputation
#define FF(a, b, c, d, x, s) {(a) += F ((b), (c), (d)) + (x); (a) = ROTATE_LEFT ((a), (s));}
#define GG(a, b, c, d, x, s) {(a) += G ((b), (c), (d)) + (x) + (UINT4)0x5a827999; (a) = ROTATE_LEFT ((a), (s));}
#define HH(a, b, c, d, x, s) {(a) += H ((b), (c), (d)) + (x) + (UINT4)0x6ed9eba1; (a) = ROTATE_LEFT ((a), (s));}

void MD4Init (MD4_CTX *context)
{
	context->count[0] = context->count[1] = 0;

	// load magic initialization constants
	context->state[0] = 0x67452301;
	context->state[1] = 0xefcdab89;
	context->state[2] = 0x98badcfe;
	context->state[3] = 0x10325476;
}

void MD4Update (MD4_CTX *context, const byte *input, uint inputLen)
{
	uint i, index, partLen;

	index = (uint)((context->count[0] >> 3) & 0x3F);

	if ((context->count[0] += ((UINT4)inputLen << 3))< ((UINT4)inputLen << 3))
		context->count[1]++;

	context->count[1] += ((UINT4)inputLen >> 29);
	partLen = 64 - index;

	if (inputLen >= partLen)
	{
 		Mem_Copy((POINTER)&context->buffer[index], (POINTER)input, partLen);
 		MD4Transform (context->state, context->buffer);

 		for (i = partLen; i + 63 < inputLen; i += 64)
 			MD4Transform (context->state, &input[i]);
  		index = 0;
	}
	else i = 0;
	Mem_Copy ((POINTER)&context->buffer[index], (POINTER)&input[i], inputLen-i);
}

void MD4Final( byte digest[16], MD4_CTX *context )
{
	byte	bits[8];
	uint	index, padLen;

	Encode (bits, context->count, 8);
	index = (unsigned int)((context->count[0] >> 3) & 0x3f);
	padLen = (index < 56) ? (56 - index) : (120 - index);
	MD4Update (context, PADDING, padLen);
	MD4Update (context, bits, 8);
	Encode (digest, context->state, 16);
	Mem_Set((POINTER)context, 0, sizeof (*context));
}

static void MD4Transform (UINT4 state[4], const byte block[64])
{
	UINT4	a = state[0], b = state[1], c = state[2], d = state[3], x[16];

	Decode(x, block, 64);

	// Round 1
	FF (a, b, c, d, x[ 0], S11); 			/* 1 */
	FF (d, a, b, c, x[ 1], S12); 			/* 2 */
	FF (c, d, a, b, x[ 2], S13); 			/* 3 */
	FF (b, c, d, a, x[ 3], S14); 			/* 4 */
	FF (a, b, c, d, x[ 4], S11); 			/* 5 */
	FF (d, a, b, c, x[ 5], S12); 			/* 6 */
	FF (c, d, a, b, x[ 6], S13); 			/* 7 */
	FF (b, c, d, a, x[ 7], S14); 			/* 8 */
	FF (a, b, c, d, x[ 8], S11); 			/* 9 */
	FF (d, a, b, c, x[ 9], S12); 			/* 10 */
	FF (c, d, a, b, x[10], S13); 			/* 11 */
	FF (b, c, d, a, x[11], S14); 			/* 12 */
	FF (a, b, c, d, x[12], S11); 			/* 13 */
	FF (d, a, b, c, x[13], S12); 			/* 14 */
	FF (c, d, a, b, x[14], S13); 			/* 15 */
	FF (b, c, d, a, x[15], S14); 			/* 16 */

	// Round 2
	GG (a, b, c, d, x[ 0], S21); 			/* 17 */
	GG (d, a, b, c, x[ 4], S22); 			/* 18 */
	GG (c, d, a, b, x[ 8], S23); 			/* 19 */
	GG (b, c, d, a, x[12], S24); 			/* 20 */
	GG (a, b, c, d, x[ 1], S21); 			/* 21 */
	GG (d, a, b, c, x[ 5], S22); 			/* 22 */
	GG (c, d, a, b, x[ 9], S23); 			/* 23 */
	GG (b, c, d, a, x[13], S24); 			/* 24 */
	GG (a, b, c, d, x[ 2], S21); 			/* 25 */
	GG (d, a, b, c, x[ 6], S22); 			/* 26 */
	GG (c, d, a, b, x[10], S23); 			/* 27 */
	GG (b, c, d, a, x[14], S24); 			/* 28 */
	GG (a, b, c, d, x[ 3], S21); 			/* 29 */
	GG (d, a, b, c, x[ 7], S22); 			/* 30 */
	GG (c, d, a, b, x[11], S23); 			/* 31 */
	GG (b, c, d, a, x[15], S24); 			/* 32 */

	// Round 3
	HH (a, b, c, d, x[ 0], S31);			/* 33 */
	HH (d, a, b, c, x[ 8], S32); 			/* 34 */
	HH (c, d, a, b, x[ 4], S33); 			/* 35 */
	HH (b, c, d, a, x[12], S34); 			/* 36 */
	HH (a, b, c, d, x[ 2], S31); 			/* 37 */
	HH (d, a, b, c, x[10], S32); 			/* 38 */
	HH (c, d, a, b, x[ 6], S33); 			/* 39 */
	HH (b, c, d, a, x[14], S34); 			/* 40 */
	HH (a, b, c, d, x[ 1], S31); 			/* 41 */
	HH (d, a, b, c, x[ 9], S32); 			/* 42 */
	HH (c, d, a, b, x[ 5], S33); 			/* 43 */
	HH (b, c, d, a, x[13], S34); 			/* 44 */
	HH (a, b, c, d, x[ 3], S31); 			/* 45 */
	HH (d, a, b, c, x[11], S32); 			/* 46 */
	HH (c, d, a, b, x[ 7], S33); 			/* 47 */
	HH (b, c, d, a, x[15], S34);			/* 48 */

	state[0] += a;
	state[1] += b;
	state[2] += c;
	state[3] += d;
	Mem_Set((POINTER)x, 0, sizeof (x));
}

static void Encode(byte *output, UINT4 *input, uint len)
{
	uint	i, j;

	for (i = 0, j = 0; j < len; i++, j += 4)
	{
 		output[j+0] = (byte)(input[i] & 0xff);
 		output[j+1] = (byte)((input[i]>>8)  & 0xff);
 		output[j+2] = (byte)((input[i]>>16) & 0xff);
 		output[j+3] = (byte)((input[i]>>24) & 0xff);
	}
}

static void Decode (UINT4 *output, const byte *input, uint len)
{
	uint i, j;

	for (i = 0, j = 0; j < len; i++, j += 4)
	{
 		output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1]) << 8) | (((UINT4)input[j+2]) << 16) | (((UINT4)input[j+3]) << 24);
	}
}

//===================================================================

uint Com_BlockChecksum (void *buffer, int length)
{
	int		digest[4];
	uint		val;
	MD4_CTX		ctx;

	MD4Init(&ctx);
	MD4Update(&ctx, (byte *)buffer, length);
	MD4Final((byte *)digest, &ctx);
	val = digest[0] ^ digest[1] ^ digest[2] ^ digest[3];

	return val;
}

uint Com_BlockChecksumKey(void *buffer, int length, int key)
{
	int		digest[4];
	uint		val;
	MD4_CTX		ctx;

	MD4Init(&ctx);
	MD4Update(&ctx, (byte *)&key, 4);
	MD4Update(&ctx, (byte *)buffer, length);
	MD4Final((byte *)digest, &ctx);
	
	val = digest[0] ^ digest[1] ^ digest[2] ^ digest[3];

	return val;
}