/* dllHeader.h */
#ifndef _DLL_H_
#define _DLL_H_

#if BUILDING_DLL
#define DLLIMPORT __declspec(dllexport)
#else
#define DLLIMPORT __declspec(dllimport)
#endif

DLLIMPORT int getCoreCount();

#endif

/* dllmain.c */
/* Replace "dll.h" with the name of your header */
#include "dllHeader.h"
#include <windows.h>
#include <malloc.h>    
#include <stdio.h>
#include <tchar.h>

typedef BOOL (WINAPI *LPFN_GLPI)(PSYSTEM_LOGICAL_PROCESSOR_INFORMATION,PDWORD);
 
DLLIMPORT int getCoreCount(){
        LPFN_GLPI glpi;
        BOOL done = FALSE;
        PSYSTEM_LOGICAL_PROCESSOR_INFORMATION buffer = NULL;
        PSYSTEM_LOGICAL_PROCESSOR_INFORMATION ptr = NULL;
        DWORD returnLength = 0;
        DWORD processorCoreCount = 0;
        DWORD byteOffset = 0;
        HINSTANCE hDll;
 
        hDll=LoadLibrary((LPCSTR)("kernel32.dll"));
        if (hDll==NULL) {
                printf("ERROR!!!\n");
                return(1);
        }
 
        glpi = (LPFN_GLPI) GetProcAddress(hDll,"GetLogicalProcessorInformation");
        if (NULL == glpi) {
                printf("\nGetLogicalProcessorInformation is not supported.\n");
                return (1);
        }
 
        while (!done) {
                DWORD rc = glpi(buffer, &returnLength);
                if (FALSE == rc) {
                        if (GetLastError() == ERROR_INSUFFICIENT_BUFFER) {
                                if (buffer)
                                        free(buffer);
                                buffer = (PSYSTEM_LOGICAL_PROCESSOR_INFORMATION)malloc(
                                                returnLength);
                                if (NULL == buffer) {
                                        printf("\nError: Allocation failure\n");
                                        return (2);
                                }
                        } else {
                                printf("\nError %d\n", GetLastError());
                                return (3);
                        }
                } else {
                        done = TRUE;
                }
        }
 
        ptr = buffer;
 
        while (byteOffset + sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION) <= returnLength) {
                if (ptr->Relationship == RelationProcessorCore) {
                        processorCoreCount++;
                }
                byteOffset += sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION);
                ptr++;
        }
/*
        printf("Number of processor cores: %d\n",
                            processorCoreCount);
*/
        free(buffer);
 
        FreeLibrary(hDll);
        return processorCoreCount;
}

BOOL WINAPI DllMain(HINSTANCE hinstDLL,DWORD fdwReason,LPVOID lpvReserved)
{
	switch(fdwReason)
	{
		case DLL_PROCESS_ATTACH:
		{
			break;
		}
		case DLL_PROCESS_DETACH:
		{
			break;
		}
		case DLL_THREAD_ATTACH:
		{
			break;
		}
		case DLL_THREAD_DETACH:
		{
			break;
		}
	}
	
	/* Return TRUE on success, FALSE on failure */
	return TRUE;
}