#include "StdAfx.h"
#include "CRC32.h"

static unsigned long CRCTable[256] = 
{
	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,0x29D9C998,0xB0D09822,0xCB4,0x59B33D17,0x2EB40D81,
    0xB7BD5C3B,0xC0BA6CAD,0xEDB88320,0x9ABFB3B6,0x03B6E20C,0x74B1D29A,
    0xEAD54739,0AF,0x04DB2615,0x73DC1683,0xE3630B12,0x94643B84,
    0x0D6D6A3E,0x7A6A5AA8,0xE40ECF0B,0x9309FF9D,0x0A00AE27,0x7D079EB1,
    0xF00F9344,0x8708A3D2,0x1E01F268,0x6906C2FE,0xF762575D,0x806567CB,
    0x196C3671,0x6E6B06E7,0xFED41B76,0,0x10DA7A5A,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,
    0x616BFFD3,0x5,0xA00AE278,0xD70DD2EE,0x4E048354,0x3903B3C2,
    0xA7672661,0xD06016F7,0x4969474D,0x3B,0xAED16A4A,0xD9D65ADC,
    0x40DF0B66,0x37D83BF0,0xA9BCAE53,0xDEBB9EC5,0x47B2CF7F,0x30B5FFE9,
    0xBDBDF21C,0xCABAC28A,0x53B39330,0x24B4A3A6,0xBAD03605,0xCDD70693,
    0x54DE5729,0x23D967BF,0xB3667A2E,0xC4614AB8,0x5D681B02,0x2A6F2B94,
    0xB40BBE37,0xC30C8EA1,0x5A05DF1B,0x2D02EF8D
};

#define DO1(buf, i)     crc = CRCTable[(crc ^ buf[i]) & 0xff] ^ (crc >> 8)
#define DO2(buf, i)     DO1(buf, i); DO1(buf, i + 1);
#define DO4(buf, i)     DO2(buf, i); DO2(buf, i + 2);
#define DO8(buf, i)     DO4(buf, i); DO4(buf, i + 4);
#define DO16(buf, i)    DO8(buf, i); DO8(buf, i + 8);

DWORD GetCRC32(const char * buf, size_t len)
{
    DWOD crc = 0xffffffff;

    if (len >= 16)
    {
        do
        {
            DO16(buf, 0);

            buf += 16;
            len -= 16;
        } while (len >= 16);
    }

    if (len != 0)
    {
        do
        {
            DO1(buf, 0);
            ++buf;
            --len;
        } while (len > 0);
    }
	
	crc ^= 0xffffffff;
	return crc;
}

#ifndef UPPER
#define UPPER(c)        (((c)>='a'  && (c) <= 'z') ? ((c)+('A'-'a')) : (c))
#endif

#define DO1CI(buf, i)   crc = CRCTable[(crc ^ UPPER(buf[i])) & 0xff] ^ (crc >> 8)
#define DO2CI(buf, i)   DO1CI(buf, i); DO1CI(buf, i + 1);
#define DO4CI(buf, i)   DO2CI(buf, i); DO2CI(buf, i + 2);
#define DOCI(buf, i)   DO4CI(buf, i); DO4CI(buf, i + 4);
#define DO16CI(buf, i)  DO8CI(buf, i); DO8CI(buf, i + 8);

DWORD GetCaseCRC32(const char * buf, size_t len)
{
    DWOD crc = 0xffffffff;

    if (16 <= len)
    {
        do
        {
            DO16CI(buf, 0);

            buf += 16;
            len -= 16;
        } while (len >= 16);
    }

    if (0 != len)
    {
        do
        {
            DO1CI(buf, 0);

            ++buf;
            --len;
        } while (len > 0);
    }

    crc ^= 0xffffffff;
    return crc;
}

DWORD GetHFILECRC32(HANDLE hFile)
{
	DWORD dwRetCRC32=0;

	DWORD dwFileSize = GetFileSize(hFile, NULL);

	DWORD dataOffset=0;
	DWORD mapSize=dwFileSize;

	SYSTEM_INFO SysInfo;
	GetSystemInfo(&SysInfo);
	
	DWORD dwSysGran = SysInfo.dwAllocationGranularity;
	DWORD dwFileMapStart = (dataOffset / dwSysGran) * dwSysGran;
	DWORD dwMapViewSize = (dataOffset % dwSysGran) + mapSize;
	//INT iViewDelta = dataOffset - dwFileMapStart;

	HANDLE hFM = CreateFileMapping(hFile,				// handle
							  NULL,					// security
							  PAGE_READONLY,		// flProtect
							  0,					// high
							  dataOffset + mapSize,	// low
							  NULL);				// name
	if (hFM)
	{	
		LPVOID lpMapData = MapViewOfFile(hFM,
									FILE_MAP_READ,
									0,
									dwFileMapStart,							
									dwMapViewSize);

		dwRetCRC32=GetCRC32((const char*)lpMapData, dwFileSize);

		
		if (lpMapData)
		{

			UnmapViewOfFile(lpMapData);
		}
		
		CloseHandle(hFM);
	}

	return dwRetCRC32;
}

DWORD GetFileCRC32(const char* c_szFileName)
{
	HANDLE hFile = CreateFile(c_szFileName,					// name of the file
						 GENERIC_READ,					// desired access
						 FILE_SHARE_READ,			// share mode
						 NULL,						// security attributes
						 OPEN_EXISTING,			// creation disposition
						 FILE_ATTRIBUTE_NORMAL,		// flags and attr
						 NULL);						// template file

	if (INVALID_HANDLE_VALUE == hFile)
		return 0;

	
	DWORD dwRetCRC32=GetHFILECRC32(hFile);
	
	CloseHandle(hFile);

	return dwRetCRC32;
}

DWORD GetFileSize(const char* c_szFileName)
{
	HANDLE hFile = CreateFile(c_szFileName,					// name of the file
						 GENERIC_READ,					// desired access
						 FILE_SHARE_READ,			// share mode
						 NULL,						// security attributes
						 OPEN_EXISTING,			// creation disposition
						 FILE_ATTRIBUTE_NORMAL,		// flags and attr
						 NULL);						// template file

	if (INVALID_HANDLE_VALUE == hFile)
		return 0;

	DWORD dwSize = GetFileSize(hFile, NULL);

	CloseHandle(hFile);

	return dwSize;
}

int main(int argc, char *argv[])
{
	int i = 0, j = 0;
	int reg, byt;
	unsigned int crc, eor;
	unsigned char trama[500000], byte = 0;
	long bytes_fichero, bytes_cogidos;

	crc = 0;

	memcpy(trama, "hola mundo", 10);
	bytes_fichero = bytes_cogidos = 10;

	while (bytes_fichero>0)
	{
		for (j = 0; j<bytes_cogidos; j++)
		{
			i = 8;
			byte = trama[j];

			crc ^= (unsigned int)byte << 24;
			for (i = 0; i<8; i++)
			{
				eor = crc & 0x80000000 ? 0x4c11db7 : 0;
				crc <<= 1;
				crc ^= eor;
			}
		}
		bytes_fichero = bytes_fichero - bytes_cogidos;
	}
	fprintf(stderr, "Valor del CRC: [%x]\n", crc);

	return 0;
}