Converted most metrics to non-wmi

Signed-off-by: Ben Ridley <benridley29@gmail.com>

headers/sysinfoapi/sysinfoapi.go

@@ -0,0 +1,43 @@
+package sysinfoapi
+
+import (
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+// MemoryStatusEx is a wrapper for MEMORYSTATUSEX
+// https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/ns-sysinfoapi-memorystatusex
+type MemoryStatusEx struct {
+	dwLength                uint32
+	DwMemoryLoad            uint32
+	UllTotalPhys            uint64
+	UllAvailPhys            uint64
+	UllTotalPageFile        uint64
+	UllAvailPageFile        uint64
+	UllTotalVirtual         uint64
+	UllAvailVirtual         uint64
+	UllAvailExtendedVirtual uint64
+}
+
+var (
+	kernel32                 = windows.NewLazySystemDLL("kernel32.dll")
+	procGetSystemInfo        = kernel32.NewProc("GetSystemInfo")
+	procGlobalMemoryStatusEx = kernel32.NewProc("GlobalMemoryStatusEx")
+)
+
+// GlobalMemoryStatusEx retrieves information about the system's current usage of both physical and virtual memory.
+// https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/nf-sysinfoapi-globalmemorystatusex
+func GlobalMemoryStatusEx() (MemoryStatusEx, error) {
+	var mse MemoryStatusEx
+	mse.dwLength = (uint32)(unsafe.Sizeof(mse))
+	pMse := uintptr(unsafe.Pointer(&mse))
+	r1, _, err := procGlobalMemoryStatusEx.Call(pMse)
+
+	if ret := *(*bool)(unsafe.Pointer(&r1)); ret == false {
+		// returned false
+		return MemoryStatusEx{}, err
+	}
+
+	return mse, nil
+}