module1.vb

来自「基于wince 4.2 .net 平台 CF1.0 SDK 做为GPS上的一」· VB 代码 · 共 65 行

Imports System.Runtime.InteropServices '引及Net框架中对底层操作支持的命名空间
Public Class clsDAMSMobileMarshal '我写的内存管理类 
#Region "与内存有关的API声明"
    REM 以下是与内存有关的移动设备API
    Public Declare Function LocalAlloc Lib "coredll.dll" Alias "LocalAlloc" (ByVal wFlags As Int32, _
    ByVal wBytes As Int32) As IntPtr

    Public Declare Function LocalFree Lib "coredll.dll" Alias "LocalFree" (ByVal hMem As Int32) As Int32


    Public Declare Function LocalLock Lib "coredll.dll" Alias "LocalLock" (ByVal hMem As Int32) As Int32

    Public Declare Function LocalReAlloc Lib "coredll.dll" Alias "LocalReAlloc" (ByVal hMem As IntPtr, _
    ByVal wBytes As Int32, ByVal wFlags As Int32) As IntPtr

#End Region

#Region "API常量声明"
    Public Const LMEM_FIXED = 0
    Public Const LMEM_MOVEABLE = &H2
    Public Const LMEM_ZEROINIT = &H40
    Public Const LPTR = LMEM_FIXED Or LMEM_ZEROINIT
#End Region

    Public Shared Function fnAllocHLocal(ByVal ni_i32Size As Int32) As IntPtr
        '申请本地内存，返回一个指向该内存块的指针
        Return LocalAlloc(LPTR, ni_i32Size)
    End Function

    Public Shared Function fnFreeHLocal(ByRef ni_pLocal As IntPtr) As Int32
        REM 释放指定的内存块柄
        Dim ti32FunctionReturnValue As Int32
        If ni_pLocal.Equals(IntPtr.Zero) = False Then
            ti32FunctionReturnValue = (LocalFree(ni_pLocal.ToInt32))
            If ti32FunctionReturnValue = 0 Then
                ni_pLocal = IntPtr.Zero
            End If
        End If
        Return (ti32FunctionReturnValue)
    End Function

    Public Shared Function fnReAllocHLocal(ByVal ni_pIn As IntPtr, ByVal ni_i32Size As Int32) As IntPtr
        '对指定的内存块重新定义大小
        Return LocalReAlloc(ni_pIn, ni_i32Size, LMEM_MOVEABLE)
    End Function

    Public Shared Function fnStringToHLocalUni(ByVal ni_strIn As String) As IntPtr
        '将指定的字符串复制到一个内存块中，并返回该内存块的指针，这个指针必须使用fnFreeHLocal函数释放
        Dim ti32StringBufLength As Int32
        Dim tpTempA As IntPtr

        If Not (ni_strIn Is Nothing) Then
            If ni_strIn.Length = 0 Then
                Return IntPtr.Zero
            Else
                ti32StringBufLength = (ni_strIn.Length + 1) * 2 ' 包括最后一个中止字符
                tpTempA = fnAllocHLocal(ti32StringBufLength)
                If tpTempA.Equals(IntPtr.Zero) = False Then '申请内存成功
                    Marshal.Copy(ni_strIn.ToCharArray, 0, tpTempA, ni_strIn.Length)
                    Return tpTempA
                End If
            End If
        End If
    End Function
End Class