allegiance/_Utility/CRC.cpp

#include "pch.h"






/****************************************************************************/

static const unsigned CRC32_TABLE[256] =
{
     0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
     0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
     0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
     0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
//            1
     0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
     0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
     0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
     0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
//            2
     0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
     0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
     0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
     0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
//           3
     0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
     0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
     0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
     0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
//           4
     0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
     0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
     0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
     0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
//           5
     0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
     0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
     0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
     0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
//           6
     0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
     0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
     0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
     0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
//           7
     0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
     0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
     0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
     0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
//           8
     0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
     0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
     0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
     0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
//           9
     0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
     0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
     0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
     0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
//           A
     0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
     0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
     0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
     0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
//           B
     0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
     0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
     0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
     0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
//           C
     0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
     0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
     0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
     0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
//           D
     0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
     0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
     0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
     0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
//           E
     0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
     0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
     0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
     0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
//           F
     0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
     0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
     0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
     0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d,
};

/****************************************************************************/

//
// DWORD update_crc (DWORD Crc, BYTE Data)
// {
//     return CRC32_TABLE[(BYTE)(Crc) ^ Data] ^ (Crc >> 8)
// }
//
// This routine computes the 32 bit CRC used by PKZIP and its derivatives,
// and by Chuck Forsberg's "ZMODEM" protocol.  The block CRC computation
// should start with high-values (0ffffffffh), and finish by inverting all
// bits.
//

#pragma warning (disable:4035)  // disable no return value warning
unsigned update_crc (unsigned Crc, const void * pData, unsigned nSize)
{
    __asm
    {
        pushf
        cld

        mov     ecx,nSize
        mov     eax,Crc
        jecxz   crc_end
        xor     edx,edx             // upper 24bits stay zeroed
        mov     esi,pData
        mov     dl,al               // preload

crc_loop:
        lodsb
        xor     dl,al

        shr     eax,8

        xor     eax,CRC32_TABLE[edx*4]

        dec     ecx
        mov     dl,al               // (interleaved)  preload for next pass
        jnz     crc_loop

crc_end:
        popf
    }

    // return value already in eax
}
#pragma warning (default:4035)  // restore no return value warning









/***************************************************************************
Function:		MemoryCRC()
Parameters:		data: pointer to data
				size: size of the data (can be zero)
Purpose:		generate a 32-bit checksum
Returns:		checksum of the data (never returns zero)
****************************************************************************/
int MemoryCRC(const void *_data, unsigned size) 
{
    int crc = (int)update_crc(0xFFFFFFFF, _data, size);

    // shouldn't ever happen, but make sure we never return 0
    if (crc == 0)  
        return 1;
	
	return crc;
}


//////////////////////////////////////////////////////////////////////////////


int FileCRC(HANDLE hFile, char * szErrorMsg) 
{
   unsigned size = GetFileSize(hFile, 0);

   if (size == 0)
       return 1;

   char *buffer = (char*)::VirtualAlloc(NULL, size, MEM_COMMIT, PAGE_READWRITE);

   if (buffer == NULL)
   {
      if(szErrorMsg)
        sprintf(szErrorMsg, "Memory error before reading file; Error Code: %d; ", GetLastError());

      return 0;
   }

   unsigned long cBytesRead;

   if (!ReadFile(hFile, buffer, size, &cBytesRead, NULL))
   {
      if(szErrorMsg)
        sprintf(szErrorMsg, "Failed read file; Error Code: %d; ", GetLastError());
      return 0;
   }

   // scan memory and determine CRC
   int nCRC = MemoryCRC (buffer, size);

   ::VirtualFree(buffer, 0, MEM_RELEASE);

   return nCRC;
}


/***************************************************************************
Function:		FileCRC()
Parameters:		szFileName:   file to get CRC from
                szErrorMsg:   this can be NULL if you don't care about a msg,
                              or else it must be able to store 100+MAX_PATH chars
Returns:        Checksum of the file, returns 0 on error
Example:		CRC = FileCRC("autoexec.bat", 0, 0);
****************************************************************************/
int FileCRC(const char *szFilename, char * szErrorMsg) 
{
   HANDLE hFile = CreateFile(szFilename, 
                             GENERIC_READ, 
                             FILE_SHARE_READ, 
                             NULL, 
                             OPEN_EXISTING, 
                             FILE_ATTRIBUTE_NORMAL, 
                             NULL);

   if (hFile == INVALID_HANDLE_VALUE)
   {
      if(szErrorMsg)
        sprintf(szErrorMsg, "Failed open file (%s); Error Code: %d ", szFilename, GetLastError());
      return 0;
   }

   int nCRC = FileCRC(hFile, szErrorMsg);

   if (nCRC == 0)
   {
      if(szErrorMsg)
          strcat(szErrorMsg, szFilename);
   }
   else
   {
       if (!::CloseHandle(hFile))
       {
          if(szErrorMsg)
              sprintf(szErrorMsg, "Couldn't close file (%s); Error Code: %d ", szFilename, GetLastError());
          return 0;
       }
   }

   return nCRC;
}