C++ DLL import in c#

Question

I have a c++ application code which I have attached below . I want to call the dll functions from a c# application . I am stuck with function pointers and explicit calling of function pointers using getProcAdress(). Please suggest a way

#include
#include
#include
//#include "ess_c.h"
/* Define functions prototype */
typedef unsigned long long(__stdcall *init)(int);
typedef int(__stdcall *serial)(unsigned long long, unsigned short *, unsigned short *);
typedef int(__stdcall *close)(unsigned long long);
typedef int(__stdcall *read2SWITCH)(unsigned long long handle, unsigned char two_switch, unsigned char * presence,
unsigned char * type, unsigned char * model, unsigned char * soft_vers, unsigned char * status, unsigned char * origin);
typedef int(__stdcall *readROTSWITCH)(unsigned long long handle, unsigned char rot_switch, unsigned char * presence,
unsigned char * type, unsigned char * model, unsigned char * soft_vers, unsigned char * err_code,
unsigned char * processing, unsigned char * position);
typedef int(__stdcall *setROTSWITCH)(unsigned long long handle, unsigned char rot_switch, unsigned char position, unsigned char direction);
int main(int argc, char *argv[])
{
/* Load DLL into memory */
HINSTANCE ProcDLL_ESS;
#ifdef _WIN64
ProcDLL_ESS = LoadLibrary(TEXT("ess_c_64.dll"));
#else
ProcDLL_ESS = LoadLibrary(TEXT("ess_c_32.dll"));
#endif
/* Declare pointers on dll functions */
init dll_init;
serial dll_serial;
close dll_close;
read2SWITCH dll_read2SWITCH;
readROTSWITCH dll_readROTSWITCH;
setROTSWITCH dll_setROTSWITCH;
/* Link dll pointers with functions prototype */
dll_init = (init)GetProcAddress(ProcDLL_ESS, "ess_initialization");
dll_serial = (serial)GetProcAddress(ProcDLL_ESS, "ess_get_serial");
dll_close = (close)GetProcAddress(ProcDLL_ESS, "ess_close");
dll_read2SWITCH = (read2SWITCH)GetProcAddress(ProcDLL_ESS, "ess_get_data_two_switch");
dll_readROTSWITCH = (readROTSWITCH)GetProcAddress(ProcDLL_ESS, "ess_get_data_rot_switch");
dll_setROTSWITCH = (setROTSWITCH)GetProcAddress(ProcDLL_ESS, "ess_set_rot_switch");
/* Define variables used for ESS */
unsigned long long essHandle = 0;
unsigned short Serial = 0;
unsigned short Version = 0;
unsigned char position = 0;
unsigned char two_switch = 0; // 2-SWITCH position (0 is the 1st on the SWITCHBOARD)
unsigned char rot_switch = 0; // ROT-SWITCH position (0 is the 1st, position 'A')
/* SWITCH variables definition used by the shared library */
unsigned char Presence;
unsigned char Type;
unsigned char Model;
unsigned char Software_Version;
unsigned char Status;
unsigned char Origin;
unsigned char Err_code;
unsigned char Processing;
unsigned char Position;
unsigned int localCount = 0;
if (ProcDLL_ESS != NULL) { // If dll loaded
std::cout << "ESS dll loaded" << std::endl;
/* Initialize device */
if (dll_init != NULL) { // Check if function was properly linked to the dll file
/* Initialize the first SWITCHBOARD in Windows enumeration list */
essHandle = dll_init(0);
std::cout << "ESS session initialized" << std::endl;
}
/* Read device serial number */
if (dll_serial != NULL) {
/*Get the serial number of the SWITCHBOARD*/
dll_serial(essHandle, &Serial, &Version);
std::cout << "SWITCH BOARD SN: " << Serial << std::endl;
}
/* Get status of the 2-SWITCH (N°1 on the board) */
if (dll_read2SWITCH != NULL){
dll_read2SWITCH(essHandle, two_switch, &Presence, &Type, &Model, &Software_Version, &Status, &Origin);
if ((Presence == 1) && (Type == 1)){ // If 2-SWITCH detected
std::cout << std::endl << "2-SWITCH detected." << std::endl;
std::cout << "Model (1 if 2-SWITCH): " << int(Model) << std::endl; // Display model
std::cout << "Software version: " << int(Software_Version) << std::endl; // Display software version
if (Status == 1){ // Display 2-SWITCH status
std::cout << "Switch is ON." << std::endl;
}
else{ std::cout << "Switch is OFF." << std::endl; }
}
else{ std::cout << "No 2-SWITCH found on 1st position." << std::endl; }
}
/* Get status of the ROT-SWITCH (N°A on the board) */
if (dll_readROTSWITCH != NULL){
dll_readROTSWITCH(essHandle, rot_switch, &Presence, &Type, &Model, &Software_Version, &Err_code, &Processing, &Position);
if ((Presence == 1) && (Type == 0)){ // If SWITCH detected
std::cout << std::endl << "ROT-SWITCH detected." << std::endl;
std::cout << "Model (1: M-SWITCH; 3: L-SWITCH): " << int(Model) << std::endl; // Display model
std::cout << "Software version: " << int(Software_Version) << std::endl; // Display software version
std::cout << "Switch position: " << int(Position) << std::endl; // Display ROT-SWITCH position
/* Change ROT-SWITCH position */
if (Position == 0){ // SWITCH changes from position 1 to 0 or from 0 to 1
dll_setROTSWITCH(essHandle, rot_switch, 1, 0);
}
else{
dll_setROTSWITCH(essHandle, rot_switch, 0, 0);
}
std::cout << "ROT-SWITCH position changed!" << std::endl;
/* Wait for processing flag to be active */
do {
dll_readROTSWITCH(essHandle, rot_switch, &Presence, &Type, &Model, &Software_Version, &Err_code, &Processing, &Position);
Sleep(100);
} while (Processing != 1);
Sleep(100);
/* Wait for processing flag to be down */
do{
dll_readROTSWITCH(essHandle, rot_switch, &Presence, &Type, &Model, &Software_Version, &Err_code, &Processing, &Position);
Sleep(100);
} while (Processing == 1);
Sleep(100);
// Read new position after change
dll_readROTSWITCH(essHandle, rot_switch, &Presence, &Type, &Model, &Software_Version, &Err_code, &Processing, &Position);
std::cout << "New Switch position: " << int(Position) << std::endl; // Display ROT-SWITCH position
}
else{ std::cout << "No ROT-SWITCH found on position 'A'." << std::endl; }
}
/* Close ESS session */
if (dll_close != NULL) {
dll_close(essHandle);
std::cout << std::endl << "ESS session closed" << std::endl;
}
}
/* Release the DLL */
FreeLibrary(ProcDLL_ESS);
std::cout << "ESS dll unloaded" << std::endl;
/* Exit application */
system("PAUSE");
return EXIT_SUCCESS;
}