util.cpp

/*
 * The GINA Bot - a computer opponent for Valve's FPS game Half-Life
 * Copyright (c) 2011, Wei Mingzhi <whistler_wmz@users.sf.net>
 *
 * This file is part of The GINA Bot.
 *
 * The GINA Bot is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 3 of the License, or (at
 * your option) any later version.
 *
 * The GINA Bot is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with The GINA Bot; if not, visit <http://www.gnu.org/licenses>.
 *
 * In addition, as a special exception, the author gives permission to
 * link the code of this program with the Half-Life Game Engine ("HL
 * Engine") and Modified Game Libraries ("MODs") developed by Valve,
 * L.L.C ("Valve").  You must obey the GNU General Public License in all
 * respects for all of the code used other than the HL Engine and MODs
 * from Valve.  If you modify this file, you may extend this exception
 * to your version of the file, but you are not obligated to do so.  If
 * you do not wish to do so, delete this exception statement from your
 * version.
 */

//
// util.cpp
//
// Utility code.  Really not optional after all.
//

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <ctype.h>
#include <limits.h>
#include <float.h>
#include <time.h>

void trim(char *str)
{
   int pos = 0;
   char *dest = str;

   // skip leading blanks
   while (str[pos] <= ' ' && str[pos] > 0)
      pos++;

   while (str[pos]) {
      *(dest++) = str[pos];
      pos++;
   }

   *(dest--) = '\0'; // store the null

   // remove trailing blanks
   while (dest >= str && *dest <= ' ' && *dest > 0)
      *(dest--) = '\0';
}

/**
 * This function converts a string to a representation of it that does not contain invalid
 * characters for the filesystem (i.e, slashes, backslashes, colons, asterisks, etc.)
 */
void NormalizeFilename(char *string)
{
   // valid character set
   char *valid_chars = "abcdefghijklmnopqrstuvwxyz"
                       "ABCDEFGHIJKLMNOPQRSTUVWXYZ" "1234567890_-.[]()";

   // let's now normalize the special characters
   while (*string) {
      // if this character doesn't appear in our valid character table...
      if (strchr(valid_chars, *string) == NULL) {
         *string = '_'; // replace it with an underscore
      }
      string++;
   }
}

// convert a string to look nice.
void Capitalize(char *sz)
{
   bool start = true;
   unsigned int length = strlen(sz);

   for (unsigned int i = 0; i < length; i++) {
      if (isalpha(sz[i])) {
         if (start) {
            sz[i] = (char)toupper(sz[i]);
         } else {
            sz[i] = (char)tolower(sz[i]);
         }
         start = false;
      }
      if (i > 2 && strchr("!.?", sz[i - 1]) && isspace(sz[i])) {
         start = true;
      }
   }
}

// remove the clan tags of a player name
void StripTags(char *buffer)
{
   char *tagstart[22] = {"-=", "-[", "-]", "-}", "-{", "<[", "<]", "[-", "]-", "{-", "}-", "[[", "[", "{", "]", "}", "<", ">", "-", "|", "=", "+"};
   char *tagstop[22] = {"=-", "]-", "[-", "{-", "}-", "]>", "[>", "-]", "-[", "-}", "-{", "]]", "]", "}", "[", "{", ">", "<", "-", "|", "=", "+"};
   int index, fieldstart, fieldstop, i, length;

   length = strlen(buffer); // get length of string

   // for each known tag...
   for (index = 0; index < 22; index++) {
      fieldstart = strstr(buffer, tagstart[index]) - buffer; // look for a tag start

      // have we found a tag start?
      if (fieldstart >= 0 && fieldstart < 32) {
         fieldstop = strstr(buffer, tagstop[index]) - buffer; // look for a tag stop

         // have we found a tag stop?
         if (fieldstop > fieldstart && fieldstop < 32) {
            for (i = fieldstart; i < length - (fieldstop + (int)strlen(tagstop[index]) - fieldstart); i++)
               buffer[i] = buffer[i + (fieldstop + (int)strlen(tagstop[index]) - fieldstart)]; // overwrite the buffer with the stripped string
            buffer[i] = '\0'; // terminate the string
         }
      }
   }

   // have we stripped too much (all the stuff)?
   if (strlen(buffer) == 0) {
      trim(buffer); // if so, string is just a tag

      // strip just the tag part...
      for (index = 0; index < 22; index++) {
         fieldstart = strstr(buffer, tagstart[index]) - buffer; // look for a tag start

         // have we found a tag start?
         if (fieldstart >= 0 && fieldstart < 32) {
            fieldstop = fieldstart + strlen(tagstart[index]); // set the tag stop

            for (i = fieldstart; i < length - (int)strlen(tagstart[index]); i++)
               buffer[i] = buffer[i + (int)strlen(tagstart[index])]; // overwrite the buffer with the stripped string
            buffer[i] = '\0'; // terminate the string

            fieldstart = strstr(buffer, tagstop[index]) - buffer; // look for a tag stop

            // have we found a tag stop ?
            if (fieldstart >= 0 && fieldstart < 32) {
               fieldstop = fieldstart + strlen(tagstop[index]); // set the tag stop

               for (i = fieldstart; i < length - (int)strlen(tagstop[index]); i++)
                  buffer[i] = buffer[i + (int)strlen(tagstop[index])]; // overwrite the buffer with the stripped string
               buffer[i] = 0; // terminate the string
            }
         }
      }
   }

   trim(buffer); // to finish, strip eventual blanks after and before the tag marks
}

static long glSeed = 0, glGen2 = 0, glGen1 = 0; // our random number generator's seed

/**
 * This function initializes the random seed based on the initial seed value passed in the
 * initial_seed parameter.
 */
void lsrand(unsigned long initial_seed)
{
   // fill in the initial seed of the random number generator
   glSeed = initial_seed;

   // Pick two large integers such that one is double the other
   glGen2 = 3719;
   glGen1 = glGen2 / 2;
}

/**
 * This function is the equivalent of the rand() standard C library function, except that
 * whereas rand() works only with short integers (i.e. not above 32767), this function is
 * able to generate 32-bit random numbers. Isn't that nice?
 */
long lrand(void)
{
   if (glSeed == 0) // if the random seed isn't initialized...
      lsrand((unsigned long)time(NULL)); // initialize it first
   glSeed = (glGen1 * glSeed) + glGen2; // do some twisted math
   return glSeed > 0 ? glSeed : -glSeed; // and return absolute value of the result
}

/**
 * This function returns a random integer number between (and including) the starting and
 * ending values passed by parameters from and to.
 */
long RandomLong(long from, long to)
{
   if (to <= from)
      return from;

   return from + lrand() / (LONG_MAX / (to - from + 1));
}

/**
 * This function returns a random floating-point number between (and including) the starting
 * and ending values passed by parameters from and to.
 */
float RandomFloat(float from, float to)
{
   if (to <= from)
      return from;

   return from + (float)lrand() / (LONG_MAX / (to - from));
}

/**
 * Assuming string is a player name, this function transforms a random equivalent in a
 * "humanized" form, i.e. without the tag marks, without trailing spaces, and optionally
 * turned into lower case.
 */
void HumanizeName(char *string)
{
   int index, length;

   // drop the tag marks when speaking to someone 75 percent of time
   if (RandomLong(1, 100) < 75)
      StripTags(string);
   else
      trim(string);

   length = strlen(string); // get name buffer's length

   // half the time switch the name to lower characters
   if (RandomLong(1, 100) < 50) {
      for (index = 0; index < length; index++) {
         // switch name buffer to lowercase
         string[index] = tolower(string[index]);
      }
   }

   string[length] = 0; // terminate the string
}

void HumanizeChat(char *buffer)
{
   int index, length, pos;
   length = strlen(buffer); // get length of string

   // 33 percent of time switch text to lowercase
   if (RandomLong(1, 100) < 33) {
      for (index = 0; index < length; index++)
         buffer[index] = tolower(buffer[index]); // switch buffer to lowercase
   }

   // if length is sufficient to assume the text had to be typed in a hurry
   if (length > 15) {
      // "length" percent of time drop a character
      if (RandomLong(1, 100) < length) {
         pos = RandomLong((int)(length / 8), length - (int)(length / 8)); // choose a random position in string
         for (index = pos; index < length - 1; index++)
            buffer[index] = buffer[index + 1]; // overwrite the buffer with the stripped string
         buffer[index] = 0; // terminate the string
         length--; // update new string length
      }

      // "length" / 2 percent of time swap a character
      if (RandomLong(1, 100) < length / 2) {
         char tempchar;
         pos = RandomLong((int)(length / 8), (int)(3 * length / 8)); // choose a random position in string
         tempchar = buffer[pos]; // swap characters
         buffer[pos] = buffer[pos + 1];
         buffer[pos + 1] = tempchar;
      }
   }

   buffer[length] = 0; // terminate the string
}

int compress(char *data_p)
{
   char *in = data_p, *out = data_p, c;
   bool newline = false, whitespace = false;

   if (in) {
      while ((c = *in) != 0) {
         if (c == '/' && in[1] == '/') {
            // skip double slash comments
            while (*in && *in != '\n') {
               in++;
            }
         } else if (c == '/' && in[1] == '*') {
            // skip /* */ comments
            while (*in && (*in != '*' || in[1] != '/'))
               in++;
            if (*in)
               in += 2;
         } else if (c == '\n' || c == '\r') {
            // record when we hit a newline
            newline = true;
            in++;
         } else if (c == ' ' || c == '\t') {
            // record when we hit whitespace
            whitespace = true;
            in++;
         } else {
            // an actual token
            // if we have a pending newline, emit it (and it counts as whitespace)
            if (newline) {
               *out++ = '\n';
               newline = false;
               whitespace = false;
            }
            if (whitespace) {
               *out++ = ' ';
               whitespace = false;
            }
            // copy quoted strings unmolested
            if (c == '"') {
               *out++ = c;
               in++;
               while (1) {
                  c = *in;
                  if (c && c != '"') {
                     *out++ = c;
                     in++;
                  } else {
                     break;
                  }
               }
               if (c == '"') {
                  *out++ = c;
                  in++;
               }
            } else {
               *out = c;
               out++;
               in++;
            }
         }
      }
   }

   *out = 0;
   return out - data_p;
}

/**
 * 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 CRC_INIT_VALUE          0xffff
#define CRC_XOR_VALUE           0x0000

static unsigned short crctable[256] = {
   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
};

void CRC_Init(unsigned short *crcvalue)
{
   *crcvalue = CRC_INIT_VALUE;
}

void CRC_ProcessByte(unsigned short *crcvalue, unsigned char data)
{
   *crcvalue = (*crcvalue << 8) ^ crctable[(*crcvalue >> 8) ^ data];
}

unsigned short CRC_Value(unsigned short crcvalue)
{
   return crcvalue ^ CRC_XOR_VALUE;
}

unsigned short CRC_Block(unsigned char *start, int count)
{
   unsigned short crc;

   CRC_Init(&crc);
   while (count--)
      crc = (crc << 8) ^ crctable[(crc >> 8) ^ *start++];

   return CRC_Value(crc);
}

#define CRC32_INIT_VALUE 0xFFFFFFFFUL
#define CRC32_XOR_VALUE  0xFFFFFFFFUL

const unsigned long crc32table[] = {
   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
};

void CRC32_Init(unsigned long *crcvalue)
{
   *crcvalue = CRC32_INIT_VALUE;
}

void CRC32_ProcessByte(unsigned long *crcvalue, unsigned char data)
{
   unsigned long crc = *crcvalue;
   crc ^= data;
   crc = crc32table[(unsigned char)crc] ^ (crc >> 8);
   *crcvalue = crc;
}

unsigned long CRC32_Value(unsigned long crcvalue)
{
   return crcvalue ^ CRC32_XOR_VALUE;
}

unsigned long CRC32_Block(unsigned char *start, int count)
{
   unsigned long ulCrc;
   CRC32_Init(&ulCrc);
   unsigned int nFront;
   int nMain;

JustAfew:
   switch (count)
   {
   case 7:
      ulCrc  = crc32table[*start++ ^ (unsigned char)ulCrc] ^ (ulCrc >> 8);

   case 6:
      ulCrc  = crc32table[*start++ ^ (unsigned char)ulCrc] ^ (ulCrc >> 8);

   case 5:
      ulCrc  = crc32table[*start++ ^ (unsigned char)ulCrc] ^ (ulCrc >> 8);

   case 4:
      ulCrc ^= *(unsigned long *)start; // Warning, this only works on little-endian.
      ulCrc = crc32table[(unsigned char)ulCrc] ^ (ulCrc >> 8);
      ulCrc = crc32table[(unsigned char)ulCrc] ^ (ulCrc >> 8);
      ulCrc = crc32table[(unsigned char)ulCrc] ^ (ulCrc >> 8);
      ulCrc = crc32table[(unsigned char)ulCrc] ^ (ulCrc >> 8);
      return CRC32_Value(ulCrc);

   case 3:
      ulCrc = crc32table[*start++ ^ (unsigned char)ulCrc] ^ (ulCrc >> 8);

   case 2:
      ulCrc = crc32table[*start++ ^ (unsigned char)ulCrc] ^ (ulCrc >> 8);

   case 1:
      ulCrc = crc32table[*start++ ^ (unsigned char)ulCrc] ^ (ulCrc >> 8);

   case 0:
      return CRC32_Value(ulCrc);
   }

   // 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 start and count in total control the
   // upfront work.
   nFront = ((unsigned int)start) & 3;
   count -= nFront;
   switch (nFront)
   {
   case 3:
      ulCrc = crc32table[*start++ ^ (unsigned char)ulCrc] ^ (ulCrc >> 8);
   case 2:
      ulCrc = crc32table[*start++ ^ (unsigned char)ulCrc] ^ (ulCrc >> 8);
   case 1:
      ulCrc = crc32table[*start++ ^ (unsigned char)ulCrc] ^ (ulCrc >> 8);
   }

   nMain = count >> 3;
   while (nMain--)
   {
      ulCrc ^= *(unsigned long *)start; // Warning, this only works on little-endian.
      ulCrc = crc32table[(unsigned char)ulCrc] ^ (ulCrc >> 8);
      ulCrc = crc32table[(unsigned char)ulCrc] ^ (ulCrc >> 8);
      ulCrc = crc32table[(unsigned char)ulCrc] ^ (ulCrc >> 8);
      ulCrc = crc32table[(unsigned char)ulCrc] ^ (ulCrc >> 8);
      ulCrc ^= *(unsigned long *)(start + 4); // Warning, this only works on little-endian.
      ulCrc = crc32table[(unsigned char)ulCrc] ^ (ulCrc >> 8);
      ulCrc = crc32table[(unsigned char)ulCrc] ^ (ulCrc >> 8);
      ulCrc = crc32table[(unsigned char)ulCrc] ^ (ulCrc >> 8);
      ulCrc = crc32table[(unsigned char)ulCrc] ^ (ulCrc >> 8);
      start += 8;
   }

   count &= 7;
   goto JustAfew;
}