/**
 * This program creates a separate thread using the CreateThread() system call.
 *
 * Figure 4.7 with annotations
 *
 * @author Gagne, Galvin, Silberschatz
 * Operating System Concepts  - Seventh Edition
 * Copyright John Wiley & Sons - 2005.
 */

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


DWORD Sum; /* data is shared by the thread(s) */

/* the thread runs in this separate function */
DWORD WINAPI Summation(PVOID Param)
{
   DWORD Upper = *(DWORD *)Param;
   
   for (DWORD i = 0; i <= Upper; i++)
      Sum += i;
   
   return 0;
}


int main(int argc, char *argv[])
{
   DWORD ThreadId;
   HANDLE ThreadHandle;
   int Param;
   
   // do some basic error checking
   if (argc != 2) {
      fprintf(stderr,"An integer parameter is required\n");
      return -1;
   }
	
   Param = atoi(argv[1]);
   
   if (Param < 0) {
      fprintf(stderr, "an integer >= 0 is required \n");
      return -1;
   }

   // create the thread
   ThreadHandle = CreateThread(NULL, 0, Summation, &Param, 0, &ThreadId);

   if (ThreadHandle != NULL) {
      WaitForSingleObject(ThreadHandle, INFINITE);
      CloseHandle(ThreadHandle);
      printf("sum = %d\n",Sum);
   }
}