Как узнать количество свободной ОЗУ?

#define DIV 1024
#define WIDTH 7
char *divisor = "K";

  MEMORYSTATUS stat;

  GlobalMemoryStatus (&stat);

printf ("The MemoryStatus structure is %ld bytes long.\n",
  stat.dwLength);
printf ("It should be %d.\n", sizeof (stat));
printf ("%ld percent of memory is in use.\n",
  stat.dwMemoryLoad);
printf ("There are %*ld total %sbytes of physical memory.\n",
  WIDTH, stat.dwTotalPhys/DIV, divisor);
printf ("There are %*ld free %sbytes of physical memory.\n",
  WIDTH, stat.dwAvailPhys/DIV, divisor);
printf ("There are %*ld total %sbytes of paging file.\n",
  WIDTH, stat.dwTotalPageFile/DIV, divisor);
printf ("There are %*ld free %sbytes of paging file.\n",
  WIDTH, stat.dwAvailPageFile/DIV, divisor);
printf ("There are %*lx total %sbytes of virtual memory.\n",
  WIDTH, stat.dwTotalVirtual/DIV, divisor);
printf ("There are %*lx free %sbytes of virtual memory.\n",
  WIDTH, stat.dwAvailVirtual/DIV, divisor);