// Crc64.cpp : 定义 DLL 应用程序的导出函数。
//

//#include "stdafx.h"
#include "Crc64.h"

#ifdef OLDCRC  
#define POLY64REV 0xd800000000000000ULL  
#define INITIALCRC    0x0000000000000000ULL  
#else  
#define POLY64REV     0x95AC9329AC4BC9B5ULL  
#define INITIALCRC    0xFFFFFFFFFFFFFFFFULL  

#define POLY32REV     0xEDB88320  
#define INITIALCRC32    (0xFFFFFFFF)  

#endif  

int crc32_table[256];

unsigned long long CRCTable[256] = { 0 };

// 这是已导出类的构造函数。
// 有关类定义的信息，请参阅 Crc64.h
CCrc64::CCrc64()
{
	int i, j;
	unsigned long long part;
	for (i = 0; i < 256; i++)
	{
		part = i;
		for (j = 0; j < 8; j++)
		{
			if (part & 1)
				part = (part >> 1) ^ POLY64REV;
			else
				part >>= 1;
		}
		CRCTable[i] = part;
	}

	return;
}


CCrc32::CCrc32()
{
	int c;
	int i = 0;
	int bit = 0;

	for (i = 0; i < 256; i++)
	{
		c = (int)i;

		for (bit = 0; bit < 8; bit++)
		{
			if (c & 1)
			{
				c = (c >> 1) ^ (POLY32REV);
			}
			else
			{
				c = c >> 1;
			}

		}
		crc32_table[i] = c;
	}


}

CCrc64 g_C_C_r_c_64;//useless .
CCrc32 g_C_C_r_c_32;//useless .

CRC64_API int GetCrc32(const char *pSrc, size_t size)
{
	int crc = INITIALCRC32;
	while (size--)
		crc = (crc >> 8) ^ (crc32_table[(crc ^ *pSrc++) & 0xff]);

	return crc;
}



CRC64_API UINT64 GetCrc64(const char *pSrc, DWORD size)
{
	unsigned long long crc = INITIALCRC;
	for (DWORD i = 0; i < size; i++)
	{
		crc = CRCTable[(crc ^ pSrc[i]) & 0xff] ^ (crc >> 8);
	}

	return crc;
}