#include <windows.h>
#include <malloc.h>    
#include <stdio.h>
#include <tchar.h>

extern "C" 
{
	typedef BOOL (WINAPI *LPFN_GLPI)(PSYSTEM_LOGICAL_PROCESSOR_INFORMATION,PDWORD);

	__declspec(dllexport) 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("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;
	}
}