Option Explicit On
Option Strict On

<System.Diagnostics.DebuggerStepThrough()> _
Friend Class CRC32

    Private crc32Table() As Integer
    Private Const BUFFER_SIZE As Integer = 1024I

    Friend Function GetCrc32(ByRef stream As System.IO.FileStream) As Integer
        Dim crc32Result As Integer = &HFFFFFFFF

        Dim buffer(BUFFER_SIZE) As Byte
        Dim readSize As Integer = BUFFER_SIZE
        Dim count As Integer = stream.Read(buffer, 0I, readSize)
        Dim i As Integer
        Dim iLookup As Integer

        Do While (count > 0I)
            For i = 0I To count - 1I
                iLookup = (crc32Result And &HFF) Xor buffer(i)
                crc32Result = ((crc32Result And &HFFFFFF00) \ &H100) And &HFFFFFF   ' nasty shr 8 with vb :/
                crc32Result = crc32Result Xor crc32Table(iLookup)
            Next i
            count = stream.Read(buffer, 0I, readSize)
        Loop
        Return Not (crc32Result)
    End Function

    Friend Function GetCrc32String(ByRef stream As System.IO.FileStream) As String
        Return String.Format("{0:X8}", GetCrc32(stream))
    End Function

    Friend Sub New()
        ' This is the official polynomial used by CRC32 in PKZip.
        ' Often the polynomial is shown reversed (04C11DB7).
        Dim dwPolynomial As Integer = &HEDB88320
        Dim i, j As Integer

        ReDim crc32Table(256I)
        Dim dwCrc As Integer

        For i = 0I To 255I
            dwCrc = i
            For j = 8I To 1I Step -1I
                If (dwCrc And 1I) > 0I Then
                    dwCrc = ((dwCrc And &HFFFFFFFE) \ 2I) And &H7FFFFFFF
                    dwCrc = dwCrc Xor dwPolynomial
                Else
                    dwCrc = ((dwCrc And &HFFFFFFFE) \ 2I) And &H7FFFFFFF
                End If
            Next j
            crc32Table(i) = dwCrc
        Next i
    End Sub
End Class

#include <fstream>
#include <iostream>
using namespace std;
const int BUFFERSIZE1 = 1024;

class CRC32
{
private:
	
	int crc32Table[];
    //const int BUFFERSIZE1 = 1024;

    int GetCrc32(ifstream& stream)
    {
        
		int crc32Result = 0xFFFFFFFF;

		BYTE buffer[BUFFERSIZE1];
		int readSize = BUFFERSIZE1;
		//stream.read( (char*)buffer, readSize);
		int count = stream.get();
		int i;
		int iLookup;

        while (count > 0)
		{
			for(i = 0; i<= count - 1;i++)
			{
                iLookup = (crc32Result & 0xFF) ^ buffer[i];
                crc32Result = 5; //((crc32Result & 0xFFFFFF00) \ 0x100) & 0xFFFFFF;/*1*/
                crc32Result = crc32Result ^ crc32Table[iLookup];
            }

			//stream.read(buffer, readSize);
            count = stream.get();
        }
        return !(crc32Result);
	}

    const char* GetCrc32String(ofstream& stream)
	{
        //Return String.Format("{0:X8}", GetCrc32(stream))
		return NULL;
    }

    void New(){
        
		//' This is the official polynomial used by CRC32 in PKZip.
        //' Often the polynomial is shown reversed (04C11DB7).
        int dwPolynomial = 0xEDB88320;
        int i, j;

        int crc32Table[256];
        int dwCrc;

        for(i = 0; i<256;i++)
		{
            dwCrc = i;
			for(j = 8; j>-1; j--)
			{
				if((dwCrc & 1) > 0)
				{
                    dwCrc = 5;//((dwCrc & 0xFFFFFFFE) \ 2) & 0x7FFFFFFF;/*2*/
                    dwCrc = dwCrc ^ dwPolynomial;
				}
                else
				{
                    dwCrc = 5; //((dwCrc & 0xFFFFFFFE) \ 2) & 0x7FFFFFFF;/*3*/
                }
            }
            crc32Table[i] = dwCrc;
        }
    }
};

#include <fstream>
#include <iostream>
using namespace std;
const int BUFFERSIZE1 = 1024;

class CRC32
{
private:
	
	int crc32Table[];
    //const int BUFFERSIZE1 = 1024;
	static char result[400];

public:
    int GetCrc32(ifstream& stream)
	{
        
		int crc32Result = 0xFFFFFFFF;

		BYTE buffer[BUFFERSIZE1];
		int readSize = BUFFERSIZE1;
		//stream.read( (char*)buffer, readSize);
		int count = stream.get();
		int i;
		int iLookup;

        while (count > 0)
		{
			for(i = 0; i<= count - 1;i++)
			{
                iLookup = (crc32Result & 0xFF) ^ buffer[i];
                crc32Result = ((crc32Result & 0xFFFFFF00) / 0x100) & 0xFFFFFF;// nasty shr 8 with vb :/
                crc32Result = crc32Result ^ crc32Table[iLookup];
            }

			//stream.read(buffer, readSize);
            count = stream.get();
        }
        return !(crc32Result);
	}

    const char* GetCrc32String(ifstream& stream)
	{
        //Return String.Format("{0:X8}", GetCrc32(stream))
		result[0]=0;
		sprintf(result, "0x%X",GetCrc32(stream));
		return result;
    }

    void New()
	{
        
		//' This is the official polynomial used by CRC32 in PKZip.
        //' Often the polynomial is shown reversed (04C11DB7).
        int dwPolynomial = 0xEDB88320;
        int i, j;

        int crc32Table[256];
        int dwCrc;

        for(i = 0; i<256;i++)
		{
            dwCrc = i;
			for(j = 8; j>-1; j--)
			{
				if((dwCrc & 1) > 0)
				{
                    dwCrc = ((dwCrc & 0xFFFFFFFE) / 2) & 0x7FFFFFFF;
                    dwCrc = dwCrc ^ dwPolynomial;
				}
                else
				{
                    dwCrc = ((dwCrc & 0xFFFFFFFE) / 2) & 0x7FFFFFFF;
                }
            }
            crc32Table[i] = dwCrc;
        }
    }
};