总共就两个部分，第一部分说几个声明API并使用的技巧，第二部分简单讲一下怎么动态调用DLL

一、动态声明

玩API的人看到前面的描述肯定会心里MMP，废话少说，看内容。

1、相对路径声明

这个最好理解

普通的API声明长这样：

Declare Function LZ4_versionNumber Lib "liblz4" Alias "_LZ4_versionNumber@0" () As Long 

下面是其FullPath版本的声明：

Declare Function LZ4_versionNumber Lib "c:\liblz4.dll" Alias "_LZ4_versionNumber@0" () As Long 

下面是其相对路径版本的声明：

Declare Function LZ4_versionNumber Lib "..\Plugins\liblz4" Alias "_LZ4_versionNumber@0" () As Long 

这特么怎么这么复杂呢，这三种都可以？下面也就简单一解释，不做深入研究，各位看官也就看看就好，能记住就记住。

先说FullPath版本，这是最低级的使用方法，一般人不会这么用；还有一种方法也可以指定FullPath，那就是使用manifest，manifest是个好东西，这个以后再扒。

然后是普通的API和相对路径的API，这俩其实是一个原理：

对于VB6，怎么检索DLL呢，当然是先检索App.Path（1、不检索子目录；2、VBA里对应Application.Path）

然后再检索环境变量目录

很多人不知道怎么看环境变量，Win+R，cmd，输入set，enter，就看到了所有环境变量

上述DLL静态声明，会在当前目录和所有环境变量目录，以相对路径检索DLL（如果多个路径都检索到，这个要应用检索规则，这里也不扒了）

假设环境变量中有一个路径：c:\xxx

那么API中的”..\Plugins\liblz4″和”liblz4″，就分别对应了路径：

“c:\xxx\..\Plugins\liblz4.dll”和”c:\xxx\liblz4.dll”

上面”..”的意思是指上一级目录，也即

“c:\xxx\..\Plugins\liblz4.dll” = “c:\Plugins\liblz4.dll”

2、动态路径

先说怎么用，声明就跟普通声明方式一样：

Declare Function LZ4_versionNumber Lib "liblz4" Alias "_LZ4_versionNumber@0" () As Long 

但是，如果这时候在环境变量目录下都没有这个dll的话

在使用这个dll之前，我们可以用LoadLibrary这个API来加载一下dll，就可以调用”LZ4_versionNumber”了

Declare声明函数时，是声明函数指针，并指明入口点，VB6会通过内部函数DllFunctionCall（该函数会调用LoadLibraryA）来调用外部API

如果Declare时，在所有路径都找不到DLL，而这时候，你主动使用LoadLibrary加载了该DLL

这时候，就解决了加载DLL的问题，相当于运行时重定向DLL

3、修改环境变量

VB6程序在加载时，会优先加载App.Path

然后会加载进程环境变量，进程环境变量

这里相关的API有5个，这里用到的就前2个：

Declare Function GetEnvironmentVariableA Lib "kernel32" (ByVal lpName As String, ByVal lpBuffer As String, ByVal nSize As Long) As Long '单个获取进程环境变量 Declare Function SetEnvironmentVariableA Lib "kernel32" (ByVal lpName As String, ByVal lpValue As String) As Long '单个设置进程环境变量 Declare Function GetEnvironmentStringsA Lib "kernel32" () As Long '获取当前进程所有环境变量 Public Declare Function SetEnvironmentStringsA Lib "kernel32" (ByVal lpszEnvironmentBlock As Long) As Long '设置当前进程所有环境变量 Public Declare Function FreeEnvironmentStringsA Lib "kernel32" (ByVal lpszEnvironmentBlock As Long) As Long '清理临时指针 

然后加环境变量就是这样操作：

 Dim lngRet As Long Dim strDest As String Dim arr() As String, i As Long Dim boolIn As Boolean '路径是否在环境变量中 Const MAX_BUFFER = 9000& strDest = String$(MAX_BUFFER, Chr(0)) GetEnvironmentVariableA "Path", strDest, MAX_BUFFER + 1 '获取当前进程的Path环境变量 lngRet = InStr(strDest, Chr(0)) strDest = Left(strDest, lngRet - 1) '清掉缓存字符 arr = Split(strDest, ";") '判断路径是否已经在环境变量中 For i = LBound(arr) To UBound(arr) If arr(i) = strMatch Then boolIn = True Exit For End If Next i If boolIn = False Then SetEnvironmentVariableA "Path", strDllPath & ";" & strDest '设置当前进程的Path环境变量，加在最前面 End If 

这样设置之后，检测DLL的时候，就多了一个自定义设置的strDllPath路径了

二、动态调用

以下内容多且复杂，初学者直接跳过，由于这里对外链卡得比较严，我就只敢贴代码。

所以，需要探讨的，在评论里交流

很多时候，开发者不想写那么多Declare，就论这个问题，其实有两个解决方案。

一个是使用tlb，现在有很多包含win32api的tlb文件，tlb文件制作简单，在编写代码时引用到工程里，发布程序时不需要附带tlb文件

还有一种方案就是动态调用：

说起来方法其实很简单

第1步：LoadLibrary，加载DLL模块到内存

第2步：GetProcAddress，获取DLL里的API函数指针

第3步：CallWindowProc或者DispCallFunc，调用函数

第4步：FreeLibrary，用完了释放函数

但是如果真的要自己去研究，而且要支持多种调用约定的话，就比较麻烦了。

像CallWindowProc，在不写汇编代码的情况下，只能支撑有4个参数的API

这里当然不会讲怎么写汇编代码，所以这里推荐几个已有的轮子：

不用知其所以然，只用知道怎么用就好。

第1个：DispCallFunc方案

vbforums论坛高人Lavolpe写的类cUniversalDLLCalls.cls，理论上支持9种调用约定

‘ for documentation on the main API DispCallFunc… http://msdn.microsoft.com/en-us/library/windows/desktop/ms%28v=vs.85%29.aspx

Private Declare Function DispCallFunc Lib “oleaut32.dll” (ByVal pvInstance As Long, ByVal offsetinVft As Long, ByVal CallConv As Long, ByVal retTYP As Integer, ByVal paCNT As Long, ByRef paTypes As Integer, ByRef paValues As Long, ByRef retVAR As Variant) As Long

Private Declare Function GetModuleHandle Lib “kernel32.dll” Alias “GetModuleHandleA” (ByVal lpModuleName As String) As Long

Private Declare Function GetProcAddress Lib “kernel32.dll” (ByVal hModule As Long, ByVal lpProcName As String) As Long

Private Declare Function LoadLibrary Lib “kernel32.dll” Alias “LoadLibraryA” (ByVal lpLibFileName As String) As Long

Private Declare Function FreeLibrary Lib “kernel32.dll” (ByVal hLibModule As Long) As Long

Private Declare Sub CopyMemory Lib “kernel32.dll” Alias “RtlMoveMemory” (ByRef Destination As Any, ByRef Source As Any, ByVal Length As Long)

Private Declare Sub FillMemory Lib “kernel32.dll” Alias “RtlFillMemory” (ByRef Destination As Any, ByVal Length As Long, ByVal Fill As Byte)

Private Declare Sub SetLastError Lib “kernel32.dll” (ByVal dwErrCode As Long)

Private Declare Function lstrlenA Lib “kernel32.dll” (ByVal lpString As Long) As Long

Private Declare Function lstrlenW Lib “kernel32.dll” (ByVal lpString As Long) As Long

‘ APIs used for _CDecl callback workarounds. See ThunkFor_CDeclCallbackToVB & ThunkRelease_CDECL

Private Declare Function VirtualAlloc Lib “kernel32” (ByVal lpAddress As Long, ByVal dwSize As Long, ByVal flAllocationType As Long, ByVal flProtect As Long) As Long

Private Declare Function VirtualFree Lib “kernel32” (ByVal lpAddress As Long, ByVal dwSize As Long, ByVal dwFreeType As Long) As Long

Public Enum CALLINGCONVENTION_ENUM

‘ http://msdn.microsoft.com/en-us/library/system.runtime.interopservices.comtypes.callconv%28v=vs.110%29.aspx

CC_FASTCALL = 0&

CC_CDECL

CC_PASCAL

CC_MACPASCAL

CC_STDCALL ‘ typical windows APIs

CC_FPFASTCALL

CC_SYSCALL

CC_MPWCDECL

CC_MPWPASCAL

End Enum

Public Enum CALLRETURNTUYPE_ENUM

CR_None = vbEmpty

CR_LONG = vbLong

CR_BYTE = vbByte

CR_INTEGER = vbInteger

CR_SINGLE = vbSingle

CR_DOUBLE = vbDouble

CR_CURRENCY = vbCurrency

‘ if the value you need isn’t in above list, you can pass the value manually to the

‘ CallFunction_DLL method below. For additional values, see:

‘ http://msdn.microsoft.com/en-us/library/cc.aspx

End Enum

Public Enum STRINGPARAMS_ENUM

STR_NONE = 0&

STR_ANSI

STR_UNICODE

End Enum

Private m_DLLname As String ‘ track last DLL loaded by this class

Private m_Mod As Long ‘ reference to loaded module

Private m_Release As Boolean ‘ whether or not we unload the module/dll

Public Function CallFunction_DLL(ByVal LibName As String, ByVal FunctionName As String, _

ByVal HasStringParams As STRINGPARAMS_ENUM, _

ByVal FunctionReturnType As CALLRETURNTUYPE_ENUM, _

ByVal CallConvention As CALLINGCONVENTION_ENUM, _

ParamArray FunctionParameters() As Variant) As Variant

‘ Used to call standard dlls, not active-x or COM objects

‘ Return value. Will be a variant containing a value of FunctionReturnType

‘ If this method fails, the return value will always be Empty. This can be verified by checking

‘ the Err.LastDLLError value. It will be non-zero if the function failed else zero.

‘ If the method succeeds, there is no guarantee that the function you called succeeded. The

‘ success/failure of that function would be indicated by this method’s return value.

‘ If calling a sub vs function & this method succeeds, the return value will be zero.

‘ Summarizing: if method fails to execute, Err.LastDLLError value will be non-zero

‘ If method executes ok, return value is from the DLL you called

‘ Parameters:

‘ LibName. The dll name. You should always include the extension else DLL is used

‘ See LoadLibrary documentation for more: http://msdn.microsoft.com/en-us/library/windows/desktop/ms%28v=vs.85%29.aspx

‘ FunctionName. The DLL function to call. This is case-senstiive

‘ To call a function by ordinal, prefix it with a hash symbol, i.e., #124

‘ HasStringParams. Provide one of the 3 available values

‘ STR_NONE. No parameters are strings or all strings are passed via StrPtr()

‘ STR_UNICODE. Any passed string values are for a Unicode function, i.e., SetWindowTextW

‘ STR_ANSI. Any passed string values are for an ANSI function, i.e., SetWindowTextA

‘ Important: If you pass one of FunctionParameters a String variable, you must include

‘ STR_UNICODE or STR_ANSI depending on what version function you are calling

‘ See the FunctionParameters section below for more

‘ FunctionReturnType. Describes what variant type the called function returns

‘ If calling a subroutine that does not return a value, use CR_None

‘ CallConvention. One of various DLL calling conventions

‘ You must know the calling convention of the function you are calling and the number

‘ of parameters, along with the parameter variable type

‘ FunctionParameters. The values and variant type for each value as required by the function

‘ you are calling. This is important. Passing incorrect variable types can cause crashes.

‘ There is no auto-conversion like VB would do for you if you were to call an API function.

‘ To ensure you pass the correct variable type, use VBs conversion routines:

‘ Passing a Long? CLng(10), CLng(x). Passing an Integer? CInt(10), CInt(x)

‘ Special cases:

‘ UDTs (structures). Pass these using VarPtr(), i.e., VarPtr(uRect)

‘ If UDT members contain static size strings, you should declare those string members

‘ as Byte arrays instead. When array is filled in by the function you called,

‘ you can use StrConv() to convert array to string.

‘ If UDT members contain dynamic size strings, you should declare those as Long.

‘ When the function returns, you can use built-in functions within this class to

‘ retrieve the string from the pointer provided to your UDT.

‘ Arrays. DO NOT pass the array. Pass only a pointer to the first member of the array,

‘ i.e., VarPtr(myArray(0)), VarPtr(myArray(0,0)), etc

‘ Strings for ANSI functions.

‘ 1) Passing by variable name or value? i.e., strContent, “Edit”, etc

‘ The string needs to be converted to ANSI, and this class will do that for you

‘ if you also pass HasStringParams as STR_ANSI. Otherwise, do NOT pass strings

‘ for ANSI functions by variable name or value. When passed by variable name,

‘ the variable contents are changed to 1 byte per character. To prevent this,

‘ pass the variable name inside parentheses, i.e., (myVariable)

‘ 2) Passing by StrPtr()? i.e, StrPtr(strContent), StrPtr(“Edit”)

‘ If the function you are calling needs the string contents, then do NOT pass

‘ the string this way. You must first convert it to ANSI. Else, you could

‘ pass it as desribed in #1 above.

‘ Rule-of-Thumb. If string is just a buffer, pass it by StrPtr(), then on return,

‘ use VB’s StrConv() to convert it from ANSI to unicode. Otherwise, pass the

‘ string by variable name or value

‘ Strings for Unicode functions

‘ 1) Passing by variable name or value? i.e., strContent, “Edit”, etc

‘ Internally, the string must be passed to the function ByVal via StrPtr().

‘ This class will do that, but it is faster (less code) if you pass all strings

‘ for unicode functions via StrPtr()

‘ 2) Passing by StrPtr()? i.e, StrPtr(strContent), StrPtr(“Edit”)

‘ Less code required, fastest method, no conversions required at all

‘ Rule-of-Thumb. All strings for unicode functions should be passed via StrPtr()

‘ Numeric values vs. variables. Be aware of the variable type of the number you pass.

‘ Depending on the value of the number, it may be Integer, Long, Double, etc.

‘ Numbers in range -32768 to 32767 are Integer, from – to are Long

‘ Fractional/decimal numbers are Double

‘ If function parameter expects Long, don’t pass just 5, pass 5& or CLng(5)

‘ Numbers as variables. Be sure the variable type matches the parameter type, i.e.,

‘ dont pass variables declared as Variant to a function expecting Long

‘// minimal sanity check for these 4 parameters:

If LibName = vbNullString Then Exit Function

If FunctionName = vbNullString Then Exit Function

If Not (FunctionReturnType And &HFFFF0000) = 0& Then Exit Function ‘ can only be 4 bytes

If HasStringParams < STR_NONE Or HasStringParams > STR_UNICODE Then Exit Function

Dim sText As String, lStrPtr As Long, lValue As Long

Const VT_BYREF As Long = &H4000&

Dim hMod As Long, fPtr As Long

Dim pIndex As Long, pCount As Long

Dim vParamPtr() As Long, vParamType() As Integer

Dim vRtn As Variant, vParams() As Variant

‘// determine if we will be loading this or already loaded

If LibName = m_DLLname Then

hMod = m_Mod ‘ already loaded

Else

If Not m_Mod = 0& Then ‘ reset m_Mod & m_Release

If m_Release = True Then FreeLibrary m_Mod

m_Mod = 0&: m_Release = False

End If

hMod = GetModuleHandle(LibName) ‘ loaded in process already?

If hMod = 0& Then ‘ if not, load it now

hMod = LoadLibrary(LibName)

If hMod = 0& Then Exit Function

m_Release = True ‘ need to use FreeLibrary at some point

End If

m_Mod = hMod ‘ cache hMod & LibName

m_DLLname = LibName

End If

fPtr = GetProcAddress(hMod, FunctionName) ‘ get the function pointer (Case-Sensitive)

If fPtr = 0& Then Exit Function ‘ abort if failure

vParams() = FunctionParameters() ‘ copy passed parameters, if any

pCount = Abs(UBound(vParams) – LBound(vParams) + 1&)

If HasStringParams > STR_NONE Then ‘ patch to ensure Strings passed as handles

For pIndex = 0& To pCount – 1& ‘ for each string param, get its StrPtr

If VarType(FunctionParameters(pIndex)) = vbString Then

CopyMemory lValue, ByVal VarPtr(FunctionParameters(pIndex)), 2&

If (lValue And VT_BYREF) = 0& Then ‘ else variant has pointer to StrPtr

lValue = VarPtr(FunctionParameters(pIndex)) + 8&

Else

CopyMemory lValue, ByVal VarPtr(FunctionParameters(pIndex)) + 8&, 4&

End If

CopyMemory lStrPtr, ByVal lValue, 4& ‘ get the StrPtr

If lStrPtr > 0& Then ‘ if not null then

If HasStringParams = STR_ANSI Then ‘ convert Unicode to ANSI

sText = FunctionParameters(pIndex) ‘ then re-write the passd String to ANSI

FillMemory ByVal lStrPtr, LenB(sText), 0

sText = StrConv(sText, vbFromUnicode)

CopyMemory ByVal lStrPtr, ByVal StrPtr(sText), LenB(sText)

End If

End If

vParams(pIndex) = lStrPtr ‘ reference the StrPtr

End If

Next

End If

‘ fill in rest of APIs parameters

If pCount = 0& Then ‘ no return value (sub vs function)

ReDim vParamPtr(0 To 0)

ReDim vParamType(0 To 0)

Else

ReDim vParamPtr(0 To pCount – 1&) ‘ need matching array of parameter types

ReDim vParamType(0 To pCount – 1&) ‘ and pointers to the parameters

For pIndex = 0& To pCount – 1&

vParamPtr(pIndex) = VarPtr(vParams(pIndex))

vParamType(pIndex) = VarType(vParams(pIndex))

Next

End If

‘ call the function now

lValue = DispCallFunc(0&, fPtr, CallConvention, FunctionReturnType, _

pCount, vParamType(0), vParamPtr(0), vRtn)

If lValue = 0& Then ‘ 0 = S_OK

If FunctionReturnType = CR_None Then

CallFunction_DLL = lValue

Else

CallFunction_DLL = vRtn ‘ return result

End If

Else

SetLastError lValue ‘ set error & return Empty

End If

End Function

Public Function CallFunction_COM(ByVal InterfacePointer As Long, ByVal VTableOffset As Long, _

ByVal FunctionReturnType As CALLRETURNTUYPE_ENUM, _

ByVal CallConvention As CALLINGCONVENTION_ENUM, _

ParamArray FunctionParameters() As Variant) As Variant

‘ Used to call active-x or COM objects, not standard dlls

‘ Return value. Will be a variant containing a value of FunctionReturnType

‘ If this method fails, the return value will always be Empty. This can be verified by checking

‘ the Err.LastDLLError value. It will be non-zero if the function failed else zero.

‘ If the method succeeds, there is no guarantee that the Interface function you called succeeded. The

‘ success/failure of that function would be indicated by this method’s return value.

‘ Typically, success is returned as S_OK (zero) and any other value is an error code.

‘ If calling a sub vs function & this method succeeds, the return value will be zero.

‘ Summarizing: if method fails to execute, Err.LastDLLError value will be non-zero

‘ If method executes ok, if the return value is zero, method succeeded else return is error code

‘ Parameters:

‘ InterfacePointer. A pointer to an object/class, i.e., ObjPtr(IPicture)

‘ Passing invalid pointers likely to result in crashes

‘ VTableOffset. The offset from the passed InterfacePointer where the virtual function exists.

‘ These offsets are generally in multiples of 4. Value cannot be negative.

‘ For the remaining parameters, see the details withn the CallFunction_DLL method.

‘ They are the same with one exception: strings. Pass the string variable name or value

‘// minimal sanity check for these 4 parameters:

If InterfacePointer = 0& Or VTableOffset < 0& Then Exit Function

If Not (FunctionReturnType And &HFFFF0000) = 0& Then Exit Function ‘ can only be 4 bytes

Dim pIndex As Long, pCount As Long

Dim vParamPtr() As Long, vParamType() As Integer

Dim vRtn As Variant, vParams() As Variant

vParams() = FunctionParameters() ‘ copy passed parameters, if any

pCount = Abs(UBound(vParams) – LBound(vParams) + 1&)

If pCount = 0& Then ‘ no return value (sub vs function)

ReDim vParamPtr(0 To 0)

ReDim vParamType(0 To 0)

Else

ReDim vParamPtr(0 To pCount – 1&) ‘ need matching array of parameter types

ReDim vParamType(0 To pCount – 1&) ‘ and pointers to the parameters

For pIndex = 0& To pCount – 1&

vParamPtr(pIndex) = VarPtr(vParams(pIndex))

vParamType(pIndex) = VarType(vParams(pIndex))

Next

End If

‘ call the function now

pIndex = DispCallFunc(InterfacePointer, VTableOffset, CallConvention, FunctionReturnType, _

pCount, vParamType(0), vParamPtr(0), vRtn)

If pIndex = 0& Then ‘ 0 = S_OK

CallFunction_COM = vRtn ‘ return result

Else

SetLastError pIndex ‘ set error & return Empty

End If

End Function

Public Function PointerToStringA(ByVal ANSIpointer As Long) As String

‘ courtesy function provided for your use as needed

‘ ANSIpointer must be a pointer to an ANSI string (1 byte per character)

Dim lSize As Long, sANSI As String

If Not ANSIpointer = 0& Then

lSize = lstrlenA(ANSIpointer)

If lSize > 0& Then

sANSI = String$(lSize \ 2& + 1&, vbNullChar)

CopyMemory ByVal StrPtr(sANSI), ByVal ANSIpointer, lSize

PointerToStringA = Left$(StrConv(sANSI, vbUnicode), lSize)

End If

End If

End Function

Public Function PointerToStringW(ByVal UnicodePointer As Long) As String

‘ courtesy function provided for your use as needed

‘ UnicodePointer must be a pointer to an unicode string (2 bytes per character)

Dim lSize As Long

If Not UnicodePointer = 0& Then

lSize = lstrlenW(UnicodePointer)

If lSize > 0& Then

PointerToStringW = Space$(lSize)

CopyMemory ByVal StrPtr(PointerToStringW), ByVal UnicodePointer, lSize * 2&

End If

End If

End Function

Public Function ThunkFor_CDeclCallbackToVB(ByVal VBcallbackPointer As Long, _

ByVal CallbackParamCount As Long) As Long

‘ this method is a workaround for cases where you are calling a CDECL function that requests

‘ a callback function address in CDECL calling convention.

‘ Ex: qsort in msvcrt20.dll uses such a callback & qsort function description found here:

‘ http://msdn.microsoft.com/en-us/library/zes7xw0h.aspx

‘ Important notes:

‘ 1) DO NOT USE this workaround when any function accepting a callback pointer,

‘ uses stdCall calling convention to that pointer. DO NOT USE this function

‘ for other than CDECL functions calling back to VB

‘ 2) This method’s return value MUST BE RELEASED via a call to ThunkRelease_CDECL method

‘ 3) The VB callback function must be a function vs. sub, even if the the callback

‘ definition describes it as a sub, i.e., returns no value, void

‘ 4) The thunk prevents VB’s stack cleaning by copying first, then replacing it after VB returns

‘ Parameters:

‘ VBcallbackPointer: the VB callback address. If function exists in a bas module, then

‘ this would be the return value of your AddressOf call. If using thunks to get addresses

‘ from class methods, then pass that thunk address as appropriate

‘ CallbackParamCount: Number of parameters your VB method accepts. This cannot be dynamic

‘ sample call: assume that vbCallBackFunction is a Public function within a bas module

‘ ————————————————————————————-

‘ Dim lCallback As Long, lThunkAddress As Long, lResult As Long

‘ lCallback = thisClass.ThunkFor_CDeclCallbackToVB(AddressOf vbCallBackFunction, 2&, lThunkAddress)

‘ ‘ now call your CDECL function, passing lCallback as the required callback address paramter,

‘ ‘ in whatever param position it is required

‘ lResult = thisClass.CallFunction_DLL(“someCDECL.dll”, “functionName”, STR_NONE, CR_LONG, _

‘ CC_CDECL, params, lCallback)

‘ ‘ destroy the thunk when no longer needed

‘ Call thisClass.ThunkRelease_CDECL(lThunkAddress)

‘ sanity checks on passed parameters

If VBcallbackPointer = 0& Or CallbackParamCount < 0& Or CallbackParamCount > 63& Then Exit Function

‘ FYI: Why is 63 the max count? CallbackParamCount stored in the thunk as unsigned byte: 63*4 =252

Dim fPtr As Long, tCode(0 To 2) As Currency

fPtr = VirtualAlloc(0&, 28&, &H1000&, &H40&) ‘ reserve memory for our virtual function

tCode(0) = 2025.6232@ ‘ thunk code is small, 28 bytes

tCode(1) = -1718.8329@

tCode(2) = -90.9419@

CopyMemory ByVal fPtr, ByVal VarPtr(tCode(0)), 24& ‘ copy to virt memmory

CopyMemory ByVal fPtr + 24&, &HC30672, 4& ‘ copy final 4 bytes also

‘ thunk uses relative address to VB function address, calc relative address & patch the thunk

CopyMemory ByVal fPtr + 10&, VBcallbackPointer – fPtr – 14&, 4&

CopyMemory ByVal fPtr + 16&, CallbackParamCount * 4&, 1& ‘ patch thunk’s param count (stack adjustment)

ThunkFor_CDeclCallbackToVB = fPtr

‘ FYI: Thunk described below. Paul Caton’s work found here:

‘ http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=49776&lngWId=1

‘==============================================================================

‘ ;FASM syntax

‘ use32 ;32bit

‘ call L1 ;Call the next instruction

‘ L1: pop eax ;Pop the return address into eax (eax = L1)

‘ pop dword [eax+(L3-L1)] ;Pop the calling cdecl function’s return address to the save location

‘ db 0E8h ;Op-code for a relative address call

‘ dd h ;Address of target vb callback function, patched at run-time

‘ sub esp, 55h ;Unfix the stack, our caller expects to do it, patched at runtime

‘ call L2 ;Call the next instruction

‘ L2: pop edx ;Pop the return address into edx (edx = L2)

‘ push dword [edx+(L3-L2)];Push the saved return address, the stack is now as it was on entry to callback_wrapper

‘ ret ;Return to caller

‘ db 0 ;Alignment pad

‘ L3: dd 0 ;Return address of the cdecl caller saved here

‘==============================================================================

End Function

Public Sub ThunkRelease_CDECL(ByVal ThunkCallBackAddress As Long)

‘ Used to release memory created during a call to the ThunkFor_CDeclCallbackToVB method.

‘ The parameter passed here must be the return value of the ThunkFor_CDeclCallbackToVB method

If Not ThunkCallBackAddress = 0& Then VirtualFree ThunkCallBackAddress, 0&, &H8000&

End Sub

Private Sub Class_Terminate()

If Not m_Mod = 0& Then

If m_Release = True Then FreeLibrary m_Mod

End If

End Sub

这个类强大的不行，使用起来也极其简单：

Private Type RECT Left As Long Top As Long Right As Long Bottom As Long End Type Private Sub Command1_Click() Dim c As cUniversalDLLCalls Dim sBuffer As String, lLen As Long Set c = New cUniversalDLLCalls '/// 1st four examples show 2 ways of calling an ANSI function & 2 ways of calling a Unicode function ' example of calling ANSI function, passing strings ByRef Debug.Print "ANSI string parameters, ByRef..." lLen = c.CallFunction_DLL("user32.dll", "GetWindowTextLengthA", STR_NONE, CR_LONG, CC_STDCALL, Me.hWnd) sBuffer = String$(lLen, vbNullChar) ' STR_ANSI + string variable name = ByRef lLen = c.CallFunction_DLL("user32.dll", "GetWindowTextA", STR_ANSI, CR_LONG, CC_STDCALL, Me.hWnd, sBuffer, lLen + 1&) Debug.Print vbTab; "form caption is: "; Left$(StrConv(sBuffer, vbUnicode), lLen); "<<<" ' example of calling ANSI function, passing strings ByVal Debug.Print "ANSI string parameters, ByVal..." lLen = c.CallFunction_DLL("user32.dll", "GetWindowTextLengthA", STR_NONE, CR_LONG, CC_STDCALL, Me.hWnd) sBuffer = String$(lLen, vbNullChar) ' STR_NONE + string variable name = ByVal. Note: Only use ANSI ByRef if string sole purpose is a buffer lLen = c.CallFunction_DLL("user32.dll", "GetWindowTextA", STR_NONE, CR_LONG, CC_STDCALL, Me.hWnd, StrPtr(sBuffer), lLen + 1&) Debug.Print vbTab; "form caption is: "; Left$(StrConv(sBuffer, vbUnicode), lLen); "<<<" ' example of calling UNICODE function, passing strings ByRef Debug.Print "Unicode string parameters, ByRef..." lLen = c.CallFunction_DLL("user32.dll", "GetWindowTextLengthW", STR_NONE, CR_LONG, CC_STDCALL, Me.hWnd) sBuffer = String$(lLen, vbNullChar) ' STR_UNICODE + string variable name = ByRef lLen = c.CallFunction_DLL("user32.dll", "GetWindowTextW", STR_UNICODE, CR_LONG, CC_STDCALL, Me.hWnd, sBuffer, lLen + 1&) Debug.Print vbTab; "form caption is: "; Left$(sBuffer, lLen); "<<<" ' example of calling UNICODE function, passing strings ByVal Debug.Print "Unicode string parameters, ByVal..." lLen = c.CallFunction_DLL("user32.dll", "GetWindowTextLengthW", STR_NONE, CR_LONG, CC_STDCALL, Me.hWnd) sBuffer = String$(lLen, vbNullChar) ' STR_NONE + StrPtr(variable name) = ByVal lLen = c.CallFunction_DLL("user32.dll", "GetWindowTextW", STR_NONE, CR_LONG, CC_STDCALL, Me.hWnd, StrPtr(sBuffer), lLen + 1&) Debug.Print vbTab; "form caption is: "; Left$(sBuffer, lLen); "<<<" '/// UDT/Array examples ' example of passing a structure Dim tRect As RECT Debug.Print "UDT/structure parameters, ByRef..." Call c.CallFunction_DLL("user32.dll", "GetWindowRect", STR_NONE, CR_LONG, CC_STDCALL, Me.hWnd, VarPtr(tRect)) Debug.Print vbTab; "window position on screen: L"; CStr(tRect.Left); ".T"; CStr(tRect.Top); " R"; CStr(tRect.Right); ".B"; CStr(tRect.Bottom) ' the RECT structure is 16 bytes, we can use an array of Long if we like Dim aRect(0 To 3) As Long Debug.Print "Array parameters, ByRef..." Call c.CallFunction_DLL("user32.dll", "GetWindowRect", STR_NONE, CR_LONG, CC_STDCALL, Me.hWnd, VarPtr(aRect(0))) Debug.Print vbTab; "window position on screen: L"; CStr(aRect(0)); ".T"; CStr(aRect(1)); " R"; CStr(aRect(2)); ".B"; CStr(aRect(3)) '/// CDecl function call Dim sFmt As String sBuffer = String$(1024, vbNullChar) sFmt = "P1=%s, P2=%d, P3=%.4f, P4=%s" ' unicode version of the function Debug.Print "CDecl Unicode parameters, ByRef..." lLen = c.CallFunction_DLL("msvcrt.dll", "swprintf", STR_UNICODE, CR_LONG, CC_CDECL, sBuffer, sFmt, "ABC", , 1.23456, "xyz") Debug.Print vbTab; "printf: "; Left$(sBuffer, lLen) ' ANSI version of the function, same parameters Debug.Print "CDecl ANSI parameters, ByRef..." lLen = c.CallFunction_DLL("msvcrt.dll", "sprintf", STR_ANSI, CR_LONG, CC_CDECL, sBuffer, (sFmt), "ABC", , 1.23456, "xyz") Debug.Print vbTab; "printf: "; Left$(StrConv(sBuffer, vbUnicode), lLen) ''/// COM object call ' All VB objects inherit from IUnknown (which has 3 virtual functions) ' IPicture inherits from IUnknown and has several virtual functions ' This example will call the 1st function which is now the 4th function, preceeded by IUnknown's 3 functions ' NOTE: simple example. We can declare a IPicture interface via VB, but many interfaces are not exposed, ' and this example indicates how to get a pointer to the interface & call functions from that pointer. ' But just like any function, you must research to determine the VTable order & function parameter ' requirements. Do not assume that some page describing the interface functions lists the functions ' in VTable order. That assumption will lead to crashes. Dim IID_IPicture As Long, aGUID(0 To 3) As Long, lPicHandle As Long Const IUnknownQueryInterface As Long = 0& ' IUnknown vTable offset to Query implemented interfaces Const IUnknownRelease As Long = 8& ' IUnkownn vTable offset to decrement reference count Const IPictureGetHandle As Long = 12& ' 4th VTable offset from IUnknown ' GUID for IPicture {7BF80980-BF32-101A-8BBB-00AA00300CAB} c.CallFunction_DLL "ole32.dll", "CLSIDFromString", STR_UNICODE, CR_LONG, CC_STDCALL, "{7BF80980-BF32-101A-8BBB-00AA00300CAB}", VarPtr(aGUID(0)) c.CallFunction_COM ObjPtr(Me.Icon), IUnknownQueryInterface, CR_LONG, CC_STDCALL, VarPtr(aGUID(0)), VarPtr(IID_IPicture) If IID_IPicture <> 0& Then ' get the icon handle & then Release the IPicture interface. QueryInterface calls AddRef internally c.CallFunction_COM IID_IPicture, 12&, CR_LONG, CC_STDCALL, VarPtr(lPicHandle) c.CallFunction_COM IID_IPicture, IUnknownRelease, CR_LONG, CC_STDCALL End If Debug.Print "COM interface call example..." Debug.Print vbTab; "Me.Icon.Handle = "; Me.Icon.Handle; " IPicture.GetHandle = "; lPicHandle ' The PointerToString methods are a courtesy '/// simple example to return a string from a pointer sFmt = "LaVolpe" Debug.Print "PointerToStringA & PointerToStringW examples..." sBuffer = c.PointerToStringW(StrPtr(sFmt)) ' unicode example Debug.Print vbTab; sBuffer; "<<<" sFmt = StrConv(sFmt, vbFromUnicode) sBuffer = c.PointerToStringA(StrPtr(sFmt)) ' ANSI example Debug.Print vbTab; sBuffer; "<<<" End Sub 

stdcall和cdecl的支持已经做进来了，其他的没有给应用案例，不知道能不能用

第2个，Paul Caton的cCallFunc2.cls，支持的调用约定stdcall、cdecl、fastcall

'********************************************************************************** '** cCallFunc2.cls - cCallFunc with added fastcall support, call by address and '** additional return types '** '** Universal dll function/sub calling class '** cdecl/stdcall/fastcall calling convention '** Call by ordinal, name or address '** Module (.bas) callbacks for cdecl. '** Object (.cls/.frm/.ctl) callbacks for cdecl/stdcall '** Support for multiple callbacks. '** Support for multiple cCallFunc2 instances '** Support unicode path\module names '** '** If you wish to do crazy stuff like CallFunc with callbacks inside a callback '** then the best solution is to make a copy of the class, eg cCallFunc1.cls, and '** use an instance of that where needed. '** '** Calling conventions: '** stdcall: parameters right to left, called routine adjusts the stack '** cdecl: parameters right to left, caller adjusts the stack '** fastcall: first parameter, if present, in the ecx register '** second parameter, if present, in the edx register '** any other parameters are pushed to the stack '** called routine adjusts the stack '** N.B. fastcall isn't standardised, differing conventions exist. '** This class supports the Microsoft/GCC implementation. '** '** paul_caton@hotmail.com '** '**  First cut....................................................... v1.00 '**  Now using virtual memory to fix a DEP issue..................... v1.01 '**  Hacked from cCDECL, now supports stdcall and ordinals........... v1.02 '**  Added support for callback objects.............................. v1.03 '**  Unicode support for paths\modules where available............... v1.04 '**  Forked from cCallFunc.cls '** Added support for fastcall calling convention '** Added CallPointer '** Changed the interface to be more property like.................. v1.05 '**  Support Byte, Integer, Long, Single and Double return types..... v1.06 '**  Added IsValidDll and IsValidMethod '** Parameter block made global '** Eliminated MAX_ARG, VB has a limit of 60 parameters '** Various optimizations........................................... v1.07 '********************************************************************************** Option Explicit 'API declarations Private Declare Function FreeLibrary Lib "kernel32" (ByVal hLibModule As Long) As Long Private Declare Function GetDesktopWindow Lib "user32" () As Long Private Declare Function GetLastError Lib "kernel32" () As Long Private Declare Function GetProcByName Lib "kernel32" Alias "GetProcAddress" (ByVal hModule As Long, ByVal lpProcName As String) As Long Private Declare Function GetProcByOrdinal Lib "kernel32" Alias "GetProcAddress" (ByVal hModule As Long, ByVal nOrdinal As Long) As Long Private Declare Function IsBadCodePtr Lib "kernel32" (ByVal lpfn As Long) As Long Private Declare Function IsWindowUnicode Lib "user32" (ByVal hWnd As Long) As Long Private Declare Function LoadLibraryA Lib "kernel32" (ByVal lpLibFileName As String) As Long Private Declare Function LoadLibraryW Lib "kernel32" (ByVal lpLibFileName As Long) As Long Private Declare Function VirtualAlloc Lib "kernel32" (ByVal lpAddress As Long, ByVal dwSize As Long, ByVal flAllocationType As Long, ByVal flProtect As Long) As Long Private Declare Function VirtualFree Lib "kernel32" (ByVal lpAddress As Long, ByVal dwSize As Long, ByVal dwFreeType As Long) As Long Private Declare Sub GetMem1 Lib "msvbvm60" (ByVal Addr As Long, RetVal As Byte) Private Declare Sub GetMem4 Lib "msvbvm60" (ByVal Addr As Long, RetVal As Long) Private Declare Sub PutMem1 Lib "msvbvm60" (ByVal Addr As Long, ByVal NewVal As Byte) Private Declare Sub PutMem2 Lib "msvbvm60" (ByVal Addr As Long, ByVal NewVal As Integer) Private Declare Sub PutMem4 Lib "msvbvm60" (ByVal Addr As Long, ByVal NewVal As Long) Private Declare Sub PutMem8 Lib "msvbvm60" (ByVal Addr As Long, ByVal NewVal As Currency) Private Declare Sub SetLastError Lib "kernel32" (ByVal dwErrCode As Long) Public Enum eObjType 'Object type for CallbackObj... also incorporates vTable offsets objCls = &H1C 'Class object callback objFrm = &H6F8 'Form object callback objCtl = &H7A4 'UserControl object callback End Enum ' ' Public Enum eReturnType 'CallFunc/CallPointer return types... also incorporates return type jump values retByte = &H0 'Return Byte retInteger = &H4 'Return Integer retLong = &H9 'Return Long retInt64 = &HD 'Return 64 bit value eg. Currency retSingle = &H14 'Return Single retDouble = &H18 'Return Double retSub = &H1A 'No return value End Enum ' ' Private Const SRC As String = "cCallFunc2." 'Error source ' Private Type tParamBlock 'Parameter block type ParamCount As Long 'Number of parameters Params(0 To 59) As Long 'Array of parameters End Type ' ' Private m_FastCall As Boolean 'FastCall private property value Private m_LastError As Long 'LastError private property value Private bUnicode As Boolean 'Unicode flag ' Private vCode As Long 'Pointer to the machine-code thunks Private vTable As Long 'Class vTable address Private nAddrPb As Long 'Address of the parameter block Private hModule As Long 'Current/last-used dll handle Private strLastDLL As String 'Current/last-used dll name Private strLastFunc As String 'Current/last-used function/sub name Private pb As tParamBlock 'Parameter block 'CallFunc: ' ' strDLL - Name of the DLL ' RetType - Function return type ' strFunc - Name of the function or it's ordinal value preceded by a '#' eg. "#2" ' ParamLongs - Any number [or none] of parameters As Long. ' To pass the address (ByRef) of a string use StrPtr, eg. StrPtr(strPath) ' To pass the address (ByRef) of a variable or UDT use VarPtr, eg. VarPtr(i) Public Function CallFunc(ByRef strDll As String, _ ByVal RetType As eReturnType, _ ByRef strFunc As String, _ ParamArray ParamLongs() As Variant) As Variant ' Dim bNewDll As Boolean 'New dll flag ' If StrComp(strDll, strLastDLL, vbTextCompare) <> 0 Then 'If the module is new Dim hMod As Long ' ' If bUnicode Then 'If unicode hMod = LoadLibraryW(StrPtr(strDll & vbNullChar)) 'Load the module with the unicode version of LoadLibrary Else ' hMod = LoadLibraryA(strDll) 'Load the module with the ascii version of LoadLibrary End If ' ' If hMod = 0 Then 'If the load failed Debug.Assert False 'Halt if running under the VB IDE Err.Raise vbObjectError + 0, SRC & "CallFunc", "DLL failed load" 'Raise an error if running compiled End If ' ' If hModule <> 0 Then 'If a module is already loaded FreeLibrary hModule 'Free the last module End If ' ' hModule = hMod 'Save the module handle strLastDLL = strDll 'Save the new module name bNewDll = True 'Indicate that it's a new module End If ' ' If bNewDll Or StrComp(strFunc, strLastFunc, vbBinaryCompare) <> 0 Then 'If the function or module is new Dim fnAddress As Long 'Function address ' If Asc(strFunc) = 35 Then 'If "#..." eg "#2", ordinal 2 fnAddress = GetProcByOrdinal(hModule, CLng(Mid$(strFunc, 2))) 'Get the address of the function by ordinal Else ' fnAddress = GetProcByName(hModule, strFunc) 'Get the address of the function by name End If ' ' If fnAddress = 0 Then 'If the function wasn't found in the module Debug.Assert False 'Halt if running under the VB IDE Err.Raise vbObjectError + 1, SRC & "CallFunc", "Function not found" 'Raise an error if running compiled End If ' ' strLastFunc = strFunc 'Save the function name PutMem4 vCode + &H19, fnAddress - vCode - (&H19 + 4) 'Patch the code with the relative address to the target function End If ' ' With pb ' Dim i As Long 'Parameter loop vars Dim j As Long 'Parameter loop vars ' j = UBound(ParamLongs) 'Get the upper parameter array bound For i = 0 To j 'For each parameter .Params(i) = ParamLongs(i) 'Store the parameter in the parameter block Next i ' ' .ParamCount = i 'Store the parameter count (j + 1) End With ' ' CallFunc = CallCommon(RetType) 'Call common code End Function ' 'CallPointer: call a function by address ' ' RetType - Function return type ' fnAddress - Address of the target function ' ParamLongs - Any number of parameters As Long, or none. ' To pass the address (ByRef) of a string use StrPtr, eg. StrPtr(strPath) ' To pass the address (ByRef) of a variable or UDT use VarPtr, eg. VarPtr(i) Public Function CallPointer(ByVal RetType As eReturnType, _ ByVal fnAddress As Long, _ ParamArray ParamLongs() As Variant) As Variant ' Dim i As Long 'Parameter loop vars Dim j As Long 'Parameter loop vars ' With pb ' j = UBound(ParamLongs) 'Get the upper parameter array bound For i = 0 To j 'For each parameter .Params(i) = ParamLongs(i) 'Store the parameter in the parameter block Next i ' ' .ParamCount = i 'Store the parameter count (j + 1) End With ' ' strLastFunc = vbNullString 'Ensure we don't clash with CallFunc caching PutMem4 vCode + &H19, fnAddress - vCode - (&H19 + 4) 'Patch the code with the relative address to the target function CallPointer = CallCommon(RetType) 'Call common code End Function 'CallbackCdecl: return a wrapper address for a bas module routine to be used as a callback for a cdecl function. ' Note: stdcall functions don't need a thunk to use a bas module function as a callback, use direct. ' ' nModFuncAddr - The address of the bas module callback function, use AddressOf to get this value ' nParms - The number of parameters that will be passed to the bas module callback function ' nIndex - Allow for multiple simultaneous callbacks Public Function CallbackCdecl(ByVal nModFuncAddr As Long, _ ByVal nParams As Long, _ Optional ByVal nIndex As Long = 1) As Long If nIndex < 1 Or nIndex > 60 Or nParams > 60 Then 'Parameter sanity checks Debug.Assert False 'Halt if running under the VB IDE Err.Raise vbObjectError + 2, SRC & "CallbackCdecl", "Invalid parameter" 'Raise error if running compiled End If ' ' CallbackCdecl = vCode + 128 + ((nIndex - 1) * 64) 'Address of the callback wrapper. Pass this return value as the callback address parameter of the cdecl function ' PutMem8 CallbackCdecl + 0, 2025.6232@ 'Callback wrapper machine code PutMem8 CallbackCdecl + 8, -1718.8339@ ' PutMem8 CallbackCdecl + 16, -9710.9163@ ' ' PutMem4 CallbackCdecl + 10, nModFuncAddr - CallbackCdecl - (10 + 4) 'Patch the code to call the vb bas module callback function PutMem1 CallbackCdecl + 16, nParams * 4 'Patch the code to apply the necessary stack adjustment End Function ' ' 'CallbackObj: return a wrapper address for an object callback from a cdecl or stdcall function ' ' objType - Callback object type ' objCallback - The callback object ' nParams - The number of parameters that will be passed to the object callback function ' nOrdinal - Callback ordinal. 1 = last private function in the callback object, 2 = second last private function in the callback object, etc ' bCDECL - Specifes whether the callback calling function is cdecl or stdcall ' nIndex - Allow for multiple simultaneous callbacks Public Function CallbackObj(ByVal objType As eObjType, _ ByRef objCallback As Object, _ ByVal nParams As Long, _ Optional ByVal nOrdinal As Long = 1, _ Optional ByVal bCDECL As Boolean = False, _ Optional ByVal nIndex As Long = 1) As Long Dim o As Long 'Object pointer Dim i As Long 'vTable entry counter Dim j As Long 'vTable address Dim n As Long 'Method pointer Dim b As Byte 'First method byte Dim m As Byte 'Known good first method byte ' If nIndex < 1 Or nIndex > 60 Or nParams > 60 Then 'Parameter sanity checks Debug.Assert False 'Halt if running under the VB IDE Err.Raise vbObjectError + 3, SRC & "CallbackObj", "Invalid parameter" 'Raise error if running compiled End If ' ' o = ObjPtr(objCallback) 'Get the callback object's address GetMem4 o, j 'Get the address of the callback object's vTable j = j + objType 'Increment to the the first user entry for this callback object type GetMem4 j, n 'Get the method pointer GetMem1 n, m 'Get the first method byte... &H33 if pseudo-code, &HE9 if native j = j + 4 'Bump to the next vtable entry ' For i = 1 To 511 'Loop through a 'sane' number of vtable entries GetMem4 j, n 'Get the method pointer ' If IsBadCodePtr(n) Then 'If the method pointer is an invalid code address GoTo vTableEnd 'We've reached the end of the vTable, exit the for loop End If ' ' GetMem1 n, b 'Get the first method byte ' If b <> m Then 'If the method byte doesn't matche the known good value GoTo vTableEnd 'We've reached the end of the vTable, exit the for loop End If ' ' j = j + 4 'Bump to the next vTable entry Next i 'Bump counter Debug.Assert False 'Halt if running under the VB IDE Err.Raise vbObjectError + 4, SRC & "CallbackObj", "Ordinal not found" 'Raise error if running compiled ' vTableEnd: 'We've hit the end of the vTable GetMem4 j - (nOrdinal * 4), n 'Get the method pointer for the specified ordinal ' CallbackObj = vCode + 128 + ((nIndex - 1) * 64) 'Address of the callback wrapper. Pass this return value as the callback address parameter ' PutMem8 CallbackObj + 0, 2877.6073@ 'Callback wrapper machine code PutMem8 CallbackObj + 8, .7235@ ' PutMem8 CallbackObj + 16, -477.8624@ ' PutMem8 CallbackObj + 24, 4580.0296@ ' PutMem8 CallbackObj + 32, -3240.1323@ ' PutMem4 CallbackObj + 40, &H ' ' PutMem1 CallbackObj + &HD, nParams 'Patch the number of params PutMem4 CallbackObj + &H19, o 'Patch the callback object PutMem4 CallbackObj + &H1E, n - CallbackObj - (&H1E + 4) 'Patch the callback call address PutMem1 CallbackObj + &H28, IIf(bCDECL, 0, nParams * 4) 'Patch the stack correction End Function ' Public Property Get FastCall() As Boolean 'Get FastCall flag FastCall = m_FastCall ' End Property ' ' Public Property Let FastCall(ByVal bValue As Boolean) 'Let Fastcall flag m_FastCall = bValue ' PutMem2 vCode + &H11, IIf(m_FastCall, &H34EB, &H9090) 'Patch the code as per FastCall status End Property ' 'IsValidDll - return whether the passed dll [path\]name is valid ' ' strDLL - [path\]name of the DLL Public Function IsValidDll(ByRef strDll As String) ' Dim hMod As Long ' ' If bUnicode Then 'If unicode hMod = LoadLibraryW(StrPtr(strDll & vbNullChar)) 'Load the module with the unicode version of LoadLibrary Else ' hMod = LoadLibraryA(strDll) 'Load the module with the ascii version of LoadLibrary End If ' ' If hMod Then 'If the library loaded okay FreeLibrary hMod 'Free the library IsValidDll = True 'Indicate success End If ' End Function ' 'IsValidMethod - return whether the passed dll [path\]name / method name is valid ' ' strDLL - [path\]name of the DLL ' strFunc - Name of the function or it's ordinal value preceded by a '#' eg. "#2" Public Function IsValidMethod(ByRef strDll As String, _ ByRef strFunc As String) ' Dim hMod As Long ' ' If bUnicode Then 'If unicode hMod = LoadLibraryW(StrPtr(strDll & vbNullChar)) 'Load the module with the unicode version of LoadLibrary Else ' hMod = LoadLibraryA(strDll) 'Load the module with the ascii version of LoadLibrary End If ' ' If hMod Then 'If the library loaded okay Dim nFuncAddr As Long 'Function address ' If Asc(strFunc) = 35 Then 'If "#..." eg "#2", ordinal 2 nFuncAddr = GetProcByOrdinal(hModule, CLng(Mid$(strFunc, 2))) 'Get the address of the function by ordinal Else ' nFuncAddr = GetProcByName(hModule, strFunc) 'Get the address of the function by name End If ' ' If nFuncAddr Then 'If the function was found in the module IsValidMethod = True 'Indicate success End If ' ' FreeLibrary hMod 'Free the library End If ' End Function ' Public Property Get LastError() As Long 'Get last error LastError = m_LastError ' End Property ' 'CallCommon: common CallFunc/CallPointer code ' ' RetType - Function return type Private Function CallCommon(ByVal RetType As eReturnType) As Variant PutMem1 vCode + &H27, RetType 'Patch the return type jump ' SetLastError 0 'Clear the error code ' 'N.B. we patch the vTable on each call because there could be multiple 'instances of this class. Multiple instances share the same code... 'and would otherwise share the vCode of the last created instance. 'So we re-patch the vTable on each call to ensure the entry is hooked 'to the instance's vCode Select Case RetType 'Select on return type Case eReturnType.retByte 'Return a Byte PutMem4 vTable + (19 * 4), vCode 'Patch the z_CallFunc_i08 entry to point to vCode CallCommon = z_CallFunc_i08(nAddrPb) 'Call ' Case eReturnType.retInteger 'Return an Integer PutMem4 vTable + (20 * 4), vCode 'Patch the z_CallFunc_i16 entry to point to vCode CallCommon = z_CallFunc_i16(nAddrPb) 'Call ' Case eReturnType.retLong 'Return a Long PutMem4 vTable + (21 * 4), vCode 'Patch the z_CallFunc_i32 entry to point to vCode CallCommon = z_CallFunc_i32(nAddrPb) 'Long ' Case eReturnType.retInt64 'Return 64bits (e.g. Currency) PutMem4 vTable + (22 * 4), vCode 'Patch the z_CallFunc_i64 entry to point to vCode CallCommon = z_CallFunc_i64(nAddrPb) 'Call ' Case eReturnType.retSingle 'Return a Single PutMem4 vTable + (23 * 4), vCode 'Patch the z_CallFunc_Sng entry to point to vCode CallCommon = z_CallFunc_Sng(nAddrPb) 'Call ' Case eReturnType.retDouble 'Return a Double PutMem4 vTable + (24 * 4), vCode 'Patch the z_CallFunc_Dbl entry to point to vCode CallCommon = z_CallFunc_Dbl(nAddrPb) 'Call ' Case eReturnType.retSub 'Subroutine, no return value PutMem4 vTable + (25 * 4), vCode 'Patch the z_CallFunc_Sub entry to point to vCode Call z_CallFunc_Sub(nAddrPb) 'Call Case Else 'Undefined return type Debug.Assert False 'Halt if running under the VB IDE Err.Raise vbObjectError + 5, SRC & "CallCommon", "Unknown return type" 'Raise error if running compiled End Select ' ' m_LastError = GetLastError() 'Get the error code End Function 'Class_Initialize: initialize the cCallFunc2 instance Private Sub Class_Initialize() ' vCode = VirtualAlloc(0, &H1000&, &H1000&, &H40&) 'Allocate 4k of read/write/executable memory ' PutMem8 vCode + 0, 7368.6248@ 'Universal function caller machine code PutMem8 vCode + 8, -0175.3831@ ' PutMem8 vCode + 16, -143.4233@ ' PutMem8 vCode + 24, 3417.828@ ' PutMem8 vCode + 32, 5568.6229@ ' PutMem8 vCode + 40, -5560.6392@ ' PutMem8 vCode + 48, -6638.7183@ ' PutMem8 vCode + 56, 752.3025@ ' PutMem8 vCode + 64, -78.4739@ ' PutMem8 vCode + 72, -635.1564@ ' PutMem8 vCode + 80, -7766.4117@ ' ' GetMem4 ObjPtr(Me), vTable 'Get the address of the class vTable ' If GetProcByName(LoadLibraryA("user32"), "IsWindowUnicode") Then 'Is IsWindowUnicode present bUnicode = IsWindowUnicode(GetDesktopWindow()) 'Determine whether we'll use the unicode version of LoadLibrary End If ' ' FastCall = False 'Default to non-Fastcall nAddrPb = VarPtr(pb) 'Address of the parameter block End Sub ' ' 'Class_Terminate: cleanup the cCallFunc2 instance Private Sub Class_Terminate() ' If hModule <> 0 Then 'If a module is loaded FreeLibrary hModule 'Free the loaded module End If ' ' VirtualFree vCode, 0, &H8000& 'Free the allocated memory End Sub '********************************************************************************************************** ' These following function's vTable method pointers are patched to point to vCode in CallFunc & CallPointer ' Note: these functions must be private and cannot be moved within this source file. '********************************************************************************************************** 'z_CallFunc_i08: return Byte Private Function z_CallFunc_i08(ByVal nParmAddr As Long) As Byte ' Debug.Assert False 'Halt if running under the VB IDE End Function ' 'z_CallFunc_i16: return Integer ' ' nParmAddr - address of the parameter block Private Function z_CallFunc_i16(ByVal nParmAddr As Long) As Integer ' Debug.Assert False 'Halt if running under the VB IDE End Function ' 'z_CallFunc_i32: return Long ' ' nParmAddr - address of the parameter block Private Function z_CallFunc_i32(ByVal nParmAddr As Long) As Long ' Debug.Assert False 'Halt if running under the VB IDE End Function ' 'z_CallFunc_i64: return int64 ' ' nParmAddr - address of the parameter block Private Function z_CallFunc_i64(ByVal nParmAddr As Long) As Currency ' Debug.Assert False 'Halt if running under the VB IDE End Function 'z_CallFunc_Sng: return Single ' ' nParmAddr - address of the parameter block Private Function z_CallFunc_Sng(ByVal nParmAddr As Long) As Single ' Debug.Assert False 'Halt if running under the VB IDE End Function ' 'z_CallFunc_Dbl: return Double ' ' nParmAddr - address of the parameter block Private Function z_CallFunc_Dbl(ByVal nParmAddr As Long) As Double ' Debug.Assert False 'Halt if running under the VB IDE End Function ' 'z_CallFunc_Sub: no return value ' ' nParmAddr - address of the parameter block Private Sub z_CallFunc_Sub(ByVal nParmAddr As Long) ' Debug.Assert False 'Halt if running under the VB IDE End Sub 

其他的应用也有很多，但是这两个类最强大，最稳健。