C / C++ / MFC

LIBRARY	"CRCDLL"
EXPORTS ComputeCrc

void __stdcall ComputeCrc(int CRCType, BYTE *Data, int Length, BYTE *TransmitFirst, BYTE *TransmitSecond);

#include "stdafx.h"
#include "CRCDLL.h"

BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
					 )
{
	switch (ul_reason_for_call)
	{
	case DLL_PROCESS_ATTACH:
	case DLL_THREAD_ATTACH:
	case DLL_THREAD_DETACH:
	case DLL_PROCESS_DETACH:
		break;
	}
    return TRUE;
}

#define CRC_A 1
#define CRC_B 2

//#define BYTE unsigned char

unsigned short UpdateCrc(unsigned char ch, unsigned short *lpwCrc)
{
	ch = (ch^(unsigned char)((*lpwCrc) & 0x00FF));
	ch = (ch^(ch<<4));
	*lpwCrc = (*lpwCrc >> 8)^((unsigned short)ch << 8)^((unsigned short)ch<<3)^((unsigned short)ch>>4);
	return(*lpwCrc);
}

void  __stdcall ComputeCrc(int CRCType, BYTE *Data, int Length, BYTE *TransmitFirst, BYTE *TransmitSecond)
{
	unsigned char chBlock;
	unsigned short wCrc;
	switch(CRCType) 
	{
	case CRC_A:
		wCrc = 0x6363;
		break;
	case CRC_B:
		wCrc = 0xFFFF; 
		break;
	default:
		return;
	}
	do 
	{
		chBlock = *Data++;
		UpdateCrc(chBlock, &wCrc);
	} while (--Length);

	if (CRCType == CRC_B)
		wCrc = ~wCrc;
	
	*TransmitFirst = (BYTE) (wCrc & 0xFF);
	*TransmitSecond = (BYTE) ((wCrc >> 8) & 0xFF);
	return;
}

Private Declare Sub ComputeCrc Lib "CRCDLL.dll" _
(ByVal CRCType As Long, Data As Byte, ByVal Length As Long, TrnasmitFirst As Byte, TransmitSecond As Byte)

Private Sub CommandButton1_Click()
    Dim Data(2) As Byte
    Dim TransmitFirst As Byte
    Dim TransmitSecond As Byte
    Data(0) = &H12
    Data(1) = &H34
    Call ComputeCrc(1, Data(0), 2, TransmitFirst, TransmitSecond)
End Sub

Muratss wrote:

I think i don't need int main block when i use this code as a dll.

Muratss wrote:

I thought i can use "Win32 Dynamic Link-Library" to get this Dll. please show me a starting point...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

// Function is used to resolve a domain name to an IP address.
// The return values are: -100 = Incorrect version of Winsock
//                        -200 = Cant resolve domain.
void __stdcall ComputeCrc(int CRCType, char *Data, int Length,
BYTE *TransmitFirst, BYTE *TransmitSecond)

</ctype.h></string.h></stdlib.h></stdio.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define CRC_A 1
#define CRC_B 2
#define BYTE unsigned char

unsigned short__stdcall UpdateCrc(unsigned char ch, unsigned short *lpwCrc) /* there is an error
{
ch = (ch^(unsigned char)((*lpwCrc) & 0x00FF));
ch = (ch^(ch<<4));
*lpwCrc = (*lpwCrc >> 8)^((unsigned short)ch << 8)^((unsigned short)ch<<3)^((unsigned short)ch>>4);
return(*lpwCrc);
}

void__stdcall ComputeCrc(int CRCType, char *Data, int Length,
BYTE *TransmitFirst, BYTE *TransmitSecond)
{
unsigned char chBlock;
unsigned short wCrc;
switch(CRCType) {
case CRC_A:
wCrc = 0x6363;
break;
case CRC_B:
wCrc = 0xFFFF; 
break;
default:
return;
}
do {
chBlock = *Data++;
UpdateCrc(chBlock, &wCrc);
} while (--Length);
if (CRCType == CRC_B)
wCrc = ~wCrc;
*TransmitFirst = (BYTE) (wCrc & 0xFF);
*TransmitSecond = (BYTE) ((wCrc >> 8) & 0xFF);
return;
}
/*BYTE BuffCRC_A[10] = {0x12, 0x34};
BYTE BuffCRC_B[10] = {0x0A, 0x12, 0x34, 0x56};
unsigned short Crc;
BYTE First, Second;
FILE *OutFd;
int i;

int main(void)
{
printf("CRC-16 reference results ISO/IEC 14443-3\n");
printf("Crc-16 G(x) = x^16 + x^12 + x^5 + 1\n\n");
printf("CRC_A of [ ");
for(i=0; i<2; i++) printf("%02X ",BuffCRC_A[i]);
ComputeCrc(CRC_A, BuffCRC_A, 2, &First, &Second);
printf("] Transmitted: %02X then %02X.\n", First, Second);
printf("CRC_B of [ ");
for(i=0; i<4; i++) printf("%02X ",BuffCRC_B[i]);
ComputeCrc(CRC_B, BuffCRC_B, 4, &First, &Second);
printf("] Transmitted: %02X then %02X.\n", First, Second);
return(0);
}*/
</ctype.h></string.h></stdlib.h></stdio.h>

LIBRARY Calculate_CRC
DESCRIPTION     'A C++ dll that can be called from VB'

EXPORTS
  ComputeCrc @1

Muratss wrote:

I started with crating "Win32 Dynamic-Link Library" project.

ComputeCRC.cpp
ComputeCRC.h
StdAfx.cpp (you'll likely not change this file)
StdAfx.h

Muratss wrote:

I have an error where UpdateCrc function is.

Muratss wrote:

You can show me a starting point?

Rajkumar R wrote:

give the Handle to Module instance of the DLL

---

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::CreateDialog( ::GetModuleInstance( _T( "<code>MyUpdateSystem.DLL</code>" ) ), 
    MAKEINTRESOURCE( IDD_DIALOGUpgrade ), NULL, NULL );