marshal.vb

从指定ＧＰＳ端口获取ＧＰＳ数据按设定发送到指定手机上！

Imports System
Imports interopserv = System.Runtime.InteropServices
Imports System.ComponentModel

'Namespace NetCF.Runtime.InteropServices

Public NotInheritable Class Marshal

	Private Class WinApi

		Public Const LMEM_FIXED As Long = 0
		Public Const LMEM_MOVEABLE As Long = 2
		Public Const LMEM_ZEROINIT As Long = &H40
		Public Const LPTR As Long = LMEM_FIXED Or LMEM_ZEROINIT

		'private constructor prevents instantiation
		Private Sub New()
		End Sub

		' imported functions
		<System.Runtime.InteropServices.DllImport("coredll.dll", SetLastError:=True)> _
		Public Shared Function LocalAlloc(ByVal uFlags As System.Int32, ByVal uBytes As System.Int32) As IntPtr
		End Function

		<System.Runtime.InteropServices.DllImport("coredll.dll", SetLastError:=True)> _
		Public Shared Function LocalFree(ByVal hMem As IntPtr) As IntPtr
		End Function

		<System.Runtime.InteropServices.DllImport("coredll.dll", SetLastError:=True)> _
		Public Shared Function LocalReAlloc(ByVal hMem As IntPtr, ByVal uBytes As System.Int64, ByVal fuFlags As System.Int64) As IntPtr
		End Function
	End Class	 'WinApi

	'private contructor prevents instantiation
	Private Sub New()
	End Sub

	'memory allocation / deallocation methods
	'/ Allocates a block of memory using LocalAlloc.
	'/ <param name="cb">The number of bytes in memory required.</param>
	'/ <returns>
	'/ An IntPtr to the newly allocated memory. This memory must be 
	'/ released using the Marshal.FreeHLocal method.
	'/ </returns>
	'/ <exception cref="OutOfMemoryException">
	'/ There is insufficient memory to satisfy the request.
	'/ </exception>
	'/ <remarks>
	'/ AllocHlocal exposes the LocalAlloc WinCE API from CoreDll.dll.
	'/ For additional information about LocalAlloc, see the MSDN Library.
	Public Shared Function AllocHLocal(ByVal cb As Int32) As IntPtr
		Try
            Return WinApi.LocalAlloc(WinApi.LPTR, cb)
		Catch ex As Exception
		End Try
    End Function

    '/ Frees memory previously allocated from the unmanaged memory
    '/ of the process with AllocHLocal.
    '/ <param name="hlocal">The handle returned by the original matching call to AllocHLocal.</param>
    '/ <exception cref="Win32Exception">
    '/ Indicates failure. The exception contains the error code obtained from GetLastError.
    '/ </exception>
    '/ <remarks>
    '/ You can use FreeHlocal to free any memory from the heap allocated by AllocHLocal or 
    '/ ReAllocHLocal, or any equivalent unmanaged API method. If the hlocal parameter is a 
    '/ null reference (Nothing in Visual Basic), the method does nothing. FreeHlOCAL exposes
    '/ the LocalFree function from CoreDll.DLL, which frees all bytes so that you can no longer 
    '/ use the memory pointed to by <paramref name="hLocal"/>. For additional information about 
    '/ LocalFree, see the MSDN Library.
    Public Shared Sub FreeHLocal(ByVal hlocal As IntPtr)
        'If hlocal <> IntPtr.Zero Then
        If hlocal.ToInt32 <> 0 Then
            'If IntPtr.Zero <> WinApi.LocalFree(hlocal) Then
            If WinApi.LocalFree(hlocal).ToInt32 <> 0 Then
                Throw New Win32Exception(interopserv.Marshal.GetLastWin32Error())
            End If
            hlocal = IntPtr.Zero
        End If
    End Sub

    '/ Resizes a block of memory previously allocated with AllocHLocal.
    '/ <param name="pv">A pointer to memory allocated with AllocHLocal.</param>
    '/ <param name="cb">The new size of the allocated block.</param>
    '/ <returns>
    '/ An IntPtr to the reallocated memory. This memory must be released
    '/ using Marshal.FreeHLocal.
    '/ </returns>
    '/ <exception cref="OutOfMemoryException">
    '/ There is insufficient memory to satisfy the request.
    '/ </exception>
    '/ <remarks>
    '/ ReAllocHLocal exposes the LocalRealloc WinCE API method from CoreDll.dll.
    '/ The returned pointer can differ from the original. For additional information
    '/ about LocalAlloc, see the MSDN Library.
    '/ </remarks>
    Public Shared Function ReAllocHLocal(ByVal pv As IntPtr, ByVal cb As Integer) As IntPtr
        Dim newMem As IntPtr = WinApi.LocalReAlloc(pv, CType(cb, System.Int64), WinApi.LMEM_MOVEABLE)
        'If newMem = IntPtr.Zero Then
        If newMem.ToInt32 = 0 Then
            Throw New OutOfMemoryException
        End If
        Return newMem
    End Function

    '/ Copies the contents of a managed String into unmanaged memory.
    '/ <param name="s">A managed string to be copied.</param>
    '/ <returns>
    '/ The address, in unmanaged memory, to where the s was copied, or 0 if a null reference
    '/ (Nothing in Visual Basic) string was supplied.
    '/ </returns>
    Public Shared Function StringToHLocalUni(ByVal s As String) As IntPtr
        If s Is Nothing Then
            Return IntPtr.Zero
        Else
            Dim nc As Integer = s.Length
            Dim len As Integer = 2 * (1 + nc)
            Dim hLocal As IntPtr = AllocHLocal(len)
            'If hLocal = IntPtr.Zero Then
            If hLocal.ToInt32 = 0 Then
                Throw New OutOfMemoryException
            Else
                interopserv.Marshal.Copy(s.ToCharArray(), 0, hLocal, s.Length)
                Return hLocal
            End If
        End If
    End Function  'StringToHLocalUni

    Public Shared Function IntToHLocalUni(ByVal s As Int32) As IntPtr
        If s = 0 Then
            Return IntPtr.Zero
        Else
            Dim nc As Integer = interopserv.Marshal.SizeOf(s)
            Dim len As Integer = 2 * (1 + nc)
            Dim hLocal As IntPtr = AllocHLocal(len)
            'If hLocal = IntPtr.Zero Then
            If hLocal.ToInt32 = 0 Then
                Throw New OutOfMemoryException
            Else
                'interopserv.Marshal.Copy(s.ToString, 0, hLocal, nc)
                Return hLocal
            End If
        End If
    End Function  'StringToHLocalUni

End Class 'Marshal
'End Namespace 'NetCF.Runtime.InteropServices