MyCom2 and the CoLib
Include masm32coliboaidl.inc
Include masm32colibcolib.inc
Includelib masm32colibcolib.lib ; new library
It is easier to create an include file to define your interface, as this gives you a running start towards creating the client program to use your new objects:
Include IMyCom2.inc
Finally, we make PUBLIC the single ClassMap so the library modules can also use it:
MyCom2ObjData STRUCT ; MyCom object private data struct Value DWORD 0 ; Value (private data member) MyCom2ObjData ENDS
This structure is inserted into an object definition. Objects MUST be defined to this pattern, with ClassDatafollowed by the custom data, and finallyanObjectEntrylist. This Each interface needs it's own ObjectEntrystructure (this is needed to "cast" the "this_" value returned from QueryInterface)
MyCom2Object STRUCT ClassData0 ClassData { } ; base values MyCom2Data MyCom2ObjData { } ; custom object data ObjectEntry0 ObjectEntry { } ; delegated Unknown ObjectEntry1 ObjectEntry { } ; IMyCom2 MyCom2Object ENDS
The interface map defines how many interfaces are supported by an object, and links to other information the maps supply. Each interface gets it's own MapItem entry. The structure needs to be defined for each object since you may include any number of interfaces in a particular object.
END_CLASS_MAP
Similarly to the InterfaceMap, END_CLASS_MAPis a macro to define a NULL interface to mark the end of theClassMap
The parameters of a ClassItem are defined as follows:
ClassItem1.m_refiid DWORD ; CLSID for the object ClassItem1.m_Flags DWORD ; flags (see below) ClassItem1.m_pTypeLibInfo DWORD ; ptr to the TypeLibInfo struct ClassItem1.m_pIMap DWORD ; ptr to the MC2InterfaceMap ClassItem1.m_pConstructor DWORD ; ptr to the object's constructor function ClassItem1.m_pDestructor DWORD ; ptr to the object's destructor function ClassItem1.m_ObjectSize DWORD ; SIZEOF the object
m_Flags is the sum of the following:
AGGREGATABLEAllows aggregation by other objects
DISPINTERFACEImplements IDispatch through a dual interface
SUPPORT_ERROR_INFOSupports rich error information for vtable clients
SUPPLY_TYPE_INFOType information may be hid with this flag
We create the MyCom2 vtable. Note the use of pvtIDispatch, which is a lib macro to add the addresses of the IUnknown and IDispatch implementations.
vtableIMyCom2 IMyCom2 { pvtIDispatch, GetValue, SetValue, RaiseValue}
We instance the object's 3 required GUIDs here. We also make pointers to these to simplify referencing them (these equated are used above) by using the DeclareGuid macro
DeclareGuid IID_IMyCom2 DeclareGuid CLSID_MyCom2 DeclareGuid LIBID_MyCom2
Similarly to C++, our objects may need custom Constructor and Destructor functions for whatever resources they need. The MyCom constructor simply needs to set the data value to zero.
Code CreateMyCom2 PROC this_:DWORD pObjectData this_, edx ; cast this_ to object data xor eax, eax ; get variable mov (MyCom2ObjData ptr [edx]).m_Value, eax ; store new value
Xor eax, eax ; return S_OK ret CreateMyCom2 ENDP
;------------------------------------------------------------------------------
Only the GetValue method is shown for example, as each work in a similar manor. The pObjectData macro is provided from the lib to convert (cast) this_ into a pointer to the object data. The pointer is placed in the register specified to the macro (here it is placed in ecx)
GetValue PROC this_:DWORD, pval:DWORD ; GetValue for the IMyCom Interface pObjectData this_, edx ; cast this_ to object data mov eax, (MyCom2ObjData ptr [edx]).m_Value ; get object data value mov ecx, pval ; get ptr to var for return mov [ecx], eax ; mov value to variable xor eax, eax ; return S_OK ret GetValue ENDP
;------------------------------------------------------------------------------
That code looks so simple it may be magic. Not really... just the special COM parts of the DLL are stuffed into the lib.
Now's the time to look at the other files required to build our DLL. These are:
· IMyCom2.inc The IMyCom interface definition in asm form
· rsrc.rc standard MASM32 resource file
· MyCom2.IDL Interface Definition File. This is compiled into MyCom.tlb
· MyCom2.def defines the exported functions for the Dynamic Link Library
As before, statements defined by the CoLib library are highlighted in blue.
--------------------------------------------------------------------------------------------------------------------
IMyCom2.inc, the interface definition
VtIMyCom2 MACRO CastName:REQ
IDispatch methods
VtIDispatch CastName
IMyCom2 methods
Amp;CastName&_GetValue comethod2 ?
Amp;CastName&_SetValue comethod2 ?
Amp;CastName&_RaiseValue comethod2 ?
ENDM
IMyCom2 STRUCT
VtIMyCom2 IMyCom2
IMyCom2 ENDS
The interface is defined as per the previous discussions in Creating COM objects in ASM (the orgional MyCom project). It is kept separate from the DLL file so it may be included in other ASM projects.
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rsrc.rc, the resource file
Get standard resources
#include <c:masm32includecolibcoserver.rc>
// type libraries here,
IDD_TypeLib TypeLib MyCom2.tlb
// add subsequent type libraries as such:
IDD_TypeLib + 1 TypeLib MyCom3.tlb
IDD_TypeLib + 2 TypeLib MyCom4.tlb
The one and only registrar script
IDD_RGS_SCRIPT REGISTRY C:masm32MyCom2MyCom2.rgs
Library MyCom2Lib
{
importlib("stdole32.tlb");
[
uuid(F8CE5E41-1135-11d4-A324-0040F6D487D9),
dual,
helpstring("IMyCom2 Dispatch Interface")
]
HKCR
{
MyCom.MyCom2.1 = s 'MyCom2 Class'
{
CLSID = s '{F8CE5E43-1135-11d4-A324-0040F6D487D9}'
}
MyCom.MyCom2 = s 'MyCom2 Class'
{
CLSID = s '{F8CE5E43-1135-11d4-A324-0040F6D487D9}'
CurVer = s 'MyCom.MyCom2.1'
}
MyCom2.def : Declares the module parameters.
LIBRARY "MyCom2.dll"