implements memory information on windows.

mem_windows.go

@@ -2,9 +2,42 @@
 
 package main
 
+import (
+	"syscall"
+	"unsafe"
+)
+
+var (
+	modKernel32          = syscall.NewLazyDLL("kernel32.dll")
+	globalMemoryStatusEx = modKernel32.NewProc("GlobalMemoryStatusEx")
+)
+
+type MEMORYSTATUSEX struct {
+	cbSize                  uint32
+	dwMemoryLoad            uint32
+	ullTotalPhys            uint64 // in bytes
+	ullAvailPhys            uint64
+	ullTotalPageFile        uint64
+	ullAvailPageFile        uint64
+	ullTotalVirtual         uint64
+	ullAvailVirtual         uint64
+	ullAvailExtendedVirtual uint64
+}
+
 func (m Mem) Virtual_memory() (Virtual_memory, error) {
 	ret := Virtual_memory{}
 
+	var memInfo MEMORYSTATUSEX
+	memInfo.cbSize = uint32(unsafe.Sizeof(memInfo))
+	mem, _, _ := globalMemoryStatusEx.Call(uintptr(unsafe.Pointer(&memInfo)))
+	if mem == 0 {
+		return ret, syscall.GetLastError()
+	}
+
+	ret.Total = memInfo.ullTotalPhys
+	ret.Available = memInfo.ullAvailPhys
+	ret.UsedPercent = float64(memInfo.dwMemoryLoad)
+	ret.Used = ret.Total - ret.Available
 	return ret, nil
 }