DLLWrapper user manual - a tool to wrap 32 bit DLLs as 64 bit DLLs
Contents
1. Es DLL Wrapper 32 bit 64 bit SoffComponents industrial quality software DLLWrapper Manual Introduction Thank you for using DLLWrapper a tool that gives you the ability to use 32 bit DLLs in a 64 bit host environment and vice versa It allows you to keep on using software and hardware you bought for a huge pile of money in the past while switching to a 64 bit Windows operating system for instance even when there are no 64 bit DLLs available to access your old software or hardware The only input that the tool needs is the original DLL that it should wrap and a C header file describing the interface functions of the DLL Ideally a suitable header file will have been delivered by the vendor of the DLL if this is not the case you ll have to write a header file by yourself by extracting the necessary information from some form of documentation that should have been provided by the vendor of the DLL at least In order to wrap for instance a 32 bit target DLL so that it can be used again in a 64 bit environment by a host program like the 64 bit version of Matlab for example the tool will generate a 64 bit wrapper DLL providing the same functions as the original 32 bit target DLL as well as a 32 bit wrapper EXE which will link the original DLL and two proxy stub DLLs for inter process communication marshalling When the 64 bit host program loads the wrapper DLL and starts calling a function provided by the DLL the function call wi2. access USBees AX oscillo http www usbee com ax html scope logic analyzer from 64 bit WrapperTestDIl Comprehensive test DLL for DLLWrapper DLL 32 and 64 bit and simply writing function parameters into file source files included sc_dll_wrapper_manual doc 2 12 20 02 2014 DLL Wrapper 32 bit 64 bit SoffComponents industrial quality software Due to legal reasons we couldn t bundle some of the example DLLs with DLLWrapper if you like to build them you ll have to install the respective third party software from the given web site first Preparing a C header file As host application with wrapper DLL on the one hand and wrapper EXE with target DLL one the other hand are running in separate processes with own address spaces all data passed to and from the DLL functions has to be copied from one address space to the other Fortunately the Microsoft COM environment provides means to automatically generate code that will do the necessary coping including packing the data on one side and unpacking it on the other side for us the so called marshalling code However the tools generating this marshalling code need precise information about the size of the memory chunks to be copied If the DLL you d like to wrap only provides functions with basic parameter and return types like int float etc all the necessary information for the marshalling is already present in a C header file describing the
3. and name necessary if header file name is different from dll file name or placed in different folder L lt path gt log file path and name for the wrapping process will lead to log code generation in the wrapping process which is very useful to investigate problems using the generated wrapper DLL generate idl file only for manual modifications possible only with full license generate products from existing idl file possible only with full license exchange wrapping direction from 32 gt 64 to 64 gt 32 bit register products after building activate logging directly only together with option R build an installation package possible only with full license set the maximal size for character strings default 1024 E X R A P C U lt size gt set the maximal size for data buffers default 1024 Interactive GUI The interactive GUI provides the same features as the command line interface version of DLLWrapper but might offer a more intuitive way of using the tool Below the Main tab of the GUI is depicted sc_dll_wrapper_manual doc 6 12 20 02 2014 Softcomponents ofp DLL Wrapper industrial quality software 32 bit gt 64 bit DLLWrapperGui a om oe id ee File License Help Main Log SoftComponents DLL Wrapper I Paths Config Path to header file 64bit to 32bit Public Documents DLL Wrapper Examples Wr
4. as an argument second level pointer or pointer to pointer DLLWrapper assumes by default that all memory pointers returned by a function are pointing to statically allocated memory and it will allocated the same amount of memory statically in the replacement DLL as there is no way for DLLWrapper anyway to find out when and how dynamically allocated memory should be freed again In case of a function returning statically allocated memory it is again essential to provide precise information for DLLWrapper about the size of the memory returned Please note if this information is wrong DLLWrapper might try to copy data beyond a valid memory chunk with might lead to an access violation in the wrapper EXE leading to a crash of it and a timeout of the inter process communication with the wrapper DLL Returning a C character string like in the case char foo void is rather uncritical as the wrapping code can determine the length of the string by searching the terminating null character it only has to be insured that the configuration parameter MAX_STR is large enough for all possible strings passed as otherwise some strings might be truncated but no access violation will occur Return pointer to a data buffer like in the case unsigned char bar void requires special care as the configuration parameter MAX_BUF has to be set exactly to the size of the returned buffer if it s set to smaller value the returned buffer will be truncated if i
5. to provide a path directly pointing to the output directory used by DLLWrapper so that copying the wrapper DLL to some other directory might not be necessary at all Please note if you re using the trial version of DLLWrapper a generated wrapper DLL will only run for 24 hours after it has been build afterwards it either has to be rebuild or you have to buy a full license 5 Furthermore it is possible to automatically generate an installation package for the built wrapper DLL using the corresponding option of the GUI or comand line interface in order to distributed it to other systems This feature is not available with the trial version of DLLWrapper sc_dll_wrapper_manual doc 5 12 20 02 2014 SoffComponents industrial quality software Es DLL Wrapper 32 bit 64 bit Command line interface The command line version of DLLWrapper expects the name and the path of a header file describing the DLL interface to be wrapped as a command line parameter Furthermore a number of additional command line options which can be prefaced by either or are supported H a help page V verbose mode echo all invocations of external tools useful to investigate problems with the build process due to failing tool invocations O lt path gt output path for products B lt path gt build path for intermediates intermediates visible only with full license D lt path gt explicit DLL file path
6. DLL interface and no modifications to the header file will be necessary in order to use it with DLLWrapper If the DLL functions use pointers to pass arrays to and from the host application by reference some modifications might be necessary however in order to provide information about the actual array size Furthermore modifications might be necessary if a header file includes some nested headers so that they can be found by DLLWrapper If you think that you might need to make modifications to a header file provided by your DLL vendor we recommend that you ll make a local copy of this header file first before starting to modify it If your DLL vendor didn t provide a C header file for the DLL at all you ll have to write one by yourself in order to provide the necessary information to DLLWrapper by extracting the information from the DLL interface documentation DLLWrapper uses the following default assumptions regarding parameter passing when parsing a given header file 1 All non pointer and non array parameters that includes struct and union types are pure inputs this is not an assumption but rather a fact as C passes all first level parameters by value and therefore must be copied only from host application to target DLL 2 All pointer parameters effectively maybe hidden by some typedefs pointing to basic data type char are assumed to be C strings with maximal length of MAX_STR 1 this configuration parameter can be changed and passe
7. able the registration of the generated wrapper during the build in order to be able to test it directly afterwards For the registration you ll need admin rights however Furthermore if registration is enabled you can activate the logging right away too With a fully licensed DLLWrapper you ll be able to stop the build process after the generation of the IDL file in order to be able to make manual modifications to it before continuing the build with an already existing IDL file Please note that in this case the IDL file is expected to be located in the sub directory lt target gt _wrapper lt target gt _idl in the build directory into which the generated idl file will be placed initially no different location can be selected sc_dll_wrapper_manual doc 7 12 20 02 2014 SoftComponents ofp DLL Wrapper industrial quality software 32 bit 64 bit Furthermore you ll be able to generate an installation package for the generated wrapper DLL in order to be able to distribute it to other systems For this additional feature you ll have to install Inno Setup as external tool to generate installation packages however Finally you can change the default maximal size for strings MAX_STR and buffers MAX_BUF in the Config section see below for an explanation of these values In the Log tab depicted below you ll be able to see messages produced by DLLWrapper and the external tools invoked by DLLWrapper like the MIDL compiler and the C c
8. additional generic function will always be generated into the wrapper DLL which can be used to directly read and write memory in the address space of the target DLL void lt target gt ReadMem void buffer unsigned long addr unsigned long size void lt target gt WriteMem unsigned long addr void buffer unsigned long size At this point the compatibility of the wrapper DLL with the target DLL is of course not 100 and programs or scripts using the DLL functions that have been written for a 32 bit host environment will have to be adopted in this case Attention please take special care when using the above function to read and or write memory in the target DLLs address space that you are providing a valid address and a valid length if the memory access will fail due to invalid address and or length the wrapper EXE server will crash and the ReadMem WriteMem function will return without result after an inter process communication timeout sc_dil_wrapper_manual doc 9 12 20 02 2014 Es DLL Wrapper 32 bit 64 bit SoffComponents industrial quality software Memory returned by function In some cases DLL functions are returning pointer to memory chunk allocated by the called function itself either statically as global but function local memory or dynamically from some form of memory heap Such a pointer could be returned as a function result or by changing a pointer which address has been passed to the function
9. apperTestDLL wrapperTestDLL32 h ese F Build only idl file Path to dill file Use existing idl file 2ublic Documents DLL Wrapper Examples WrapperTestDLL wrapperTestDLL 32 dll jess V Register after building needs admin Build path f Test jase V Activate logging Output path F Build install package f Test eal JF Default buffer size Logging 1024 E Generate logging code Default string size Logging file for wrapping exe 1024 z C Users TK Documents dilwrapper log eas Status IDLE In the Paths section of the GUI you can select or enter the path to and the name of the header file describing the DLL exports the path to and the name of the target DLL that should be wrapped the build path where the intermediate files should be placed and the output path where the final products should be placed Note that in the trail version of the tool you can t select a build path because all intermediate files will be deleted right away during the build In the Logging section of the GUI you can activate the generation of logging code into the wrapper EXE server which is very helpful in finding problems with wrapped DLL functions see the chapter Troubleshooting below Furthermore you can select a path and a name for the logging file In the Config section you can change some settings for the wrapping procedure You can reverse the wrapping direction to wrap 64 bit DLLs as 32 bit DLLs and you can en
10. as well as one item to close the tool Under the License menu you ll find two items to buy or update to a full license for DLLWrapper The Buy license item will lead you to our web site where you can directly purchase a full license for DLLWrapper We ll deliver a license file to you via e mail after receiving your payment and you ll be able to upgrade your installed trail version of DLLWrapper to a full featured version without any limitations by using the Update license item to select the license file you received and saved somewhere in your file system Finally under the Help menu you ll find one item to open this DLLWrapper user manual in the chm help file format used by recent Windows versions a link to a PDF version of this sc_dll_wrapper_manual doc 8 12 20 02 2014 DLL Wrapper 32 bit 64 bit SoftComponents industrial quality software document can be found in the start menu Furthermore you ll find a menu item giving you information about you ll license type trail or full and our contact e mail address Limitations Handle like function parameters As DLLWrapper is trying to convert in process function calls to a target DLL in the same process environment into out of process COM calls with two processes in different environments there are some limitations regarding the indirect passing of memory As there is no single address space any more between the wrapped target DLL and the host application memory ad
11. bit host application the replacement DLL will be called lt target gt _32 dll while the replacement process will be called lt target gt _64 exe Please note if you re using the trial version of DLLWrapper the successful building of a wrapper will only be possible for thirty times afterwards you ll have to buy a full license Using a wrapper DLL After generating a wrapper DLL and the accompanying files the new COM objects realizing the inter process communication between 64 bit host application and 32 bit target DLL have to be registered with the Windows COM system For that you ll have to execute the generated batch file lt target gt _reg bat or you can choose to directly register the COM objects after building a wrapper by using the respective GUI or command line option Please note that you ll need at least temporary admin rights on your machine for that Afterwards the wrapper DLL can be used by a host application by simply copying it to a place where it can be found by the host application you can either copy the DLL to the system32 subdirectory of your windows installation in case it s a 64 bit DLL otherwise you ll have to copy it to the syswow64 directory in case it s a 32 bit DLL or into the directory where the exe file of the host application is located Please note that you might need temporary admin rights on your machine for that If your host application uses run time linkage instead of load time linkage it might be possible
12. d by inter process communication significantly If you retrieve from the documentation of your DLL that the function foo does not change the contents of the array tab passed to it for instance you should change void foo int tab 16 into void foo const int tab 16 sc_dll_wrapper_manual doc 4 12 20 02 2014 Es DLL Wrapper 32 bit 64 bit SoffComponents industrial quality software Generating a wrapper DLL After you have prepared the necessary C header file you can either use the command line version of DLLWrapper or a little GUI to generate a wrapper DLL for your given original target DLL Both the command line interface and the GUI are described in detail below In both cases you can pass an output directory in which the final products should be placed For a DLL named lt target gt dll with a corresponding header file lt target gt h the following products will be generated when wrapping a 32 bit DLL lt target gt _64 dll 64 bit wrapper DLL replacement DLL for 32 bit target DLL lt target gt _32 exe 32 bit wrapper EXE replacement process to host 32 bit target DLL lt target gt _stub dll 32 bit marshalling code lt target gt _proxy dll_ 64 bit marshalling code lt target gt _reg bat Batch file to register COM objects needs for inter process communication lt target gt _unreg bat Batch file to unregister COM objects When wrapping a 64 bit target DLL to be called from a 32
13. d in the Log tab You can copy and paste this command line setting to a console window and add the verbose mode command line switch there sc_dll_wrapper_manual doc 11 12 20 02 2014 Es DLL Wrapper 32 bit 64 bit SoffComponents industrial quality software Logging code You can enable the generation of logging code into the wrapper EXE This code will not be active by default but can be activated by writing a registry key specific to the wrapper DLL This can easily been done either for testing purposes right after building the wrapper DLL by using the respective GUI option or the command line option A or later maybe even on a different target machine by calling the generated lt DLL Name gt _reg bat batch file with the option Logging to switch it on or without the option to switch logging of again If logging code has been generated and the logging feature has been activated every function invocation made through the generated wrapper EXE server to the original target DLL is logged with the values of all function parameters passed and the return value given back This can be very helpful in order to find problems that occur when calling specific wrapped functions through the wrapper DLL from a 64 bit host application for instance Of course this logging of every single function call can slow the DLL functions and possible the whole system down quite significantly so the logging feature should be deactivated again after finding a p
14. d via GUI or command line interface Furthermore it is considered that the pointer could also be a NULL pointer 3 All pointer parameters effectively maybe hidden by some typedefs pointing to basic data type unsigned char are assumed to be raw data buffers with maximal length of MAX_BUF this configuration parameter can be changed and passed via GUI or command line interface too Furthermore it is considered that the pointer could also be a NULL pointer 4 All other pointers are assumed to point to exactly one object of the referred data type that means it is NOT assumed that pointer types other than in the two cases above are pointer to arrays by default Furthermore it is considered that the pointer could also be a NULL pointer 5 Arrays with a given size passed as function parameters which are always passed by reference in C are handled as such 6 If a pointer points to a data type marked as const it is assumed that this memory will be read only for the function it is passed to and therefore it will only be copied from sc_dll_wrapper_manual doc 3 12 20 02 2014 Softcomponents Sfp DLL Wrapper industrial quality software 32 bit gt 64 bit host application to target DLL If a pointer points to a data type NOT marked as const however it is assumed that the called function will change the contents of the memory passed and therefore it will also be copied from target DLL to host application again after the call 7 Pointer
15. dresses passed directly and unchanged from the host application to the target DLL and vice versa wouldn t have a useful meaning in the respective other address space However there are cases in which it is necessary to pass an unchanged memory address from the target DLL to the host application if this memory address is used as a kind of handle for later calls to other DLL functions for instance see our USBAXLA example for the USBee AX Oscilloscope Logic Analyzer where such a case occurred In this case you ll have to change the data type of the respective pointer parameters into unsigned long if wrapping a 32 bit target dll or unsigned long long if wrapping a 64 bit target DLL In the USBAXLA example we had to change the following function prototypes for instance extern unsigned long MakeBuffer unsigned long size extern int DeleteBuffer unsigned long buffer into this extern unsigned long MakeBuffer unsigned long size extern int DeleteBuffer unsigned long buffer as the pointer returned by the function MakeBuffer is used as a pointer to data but also as a handle for an allocated buffer which has to be passed to the function DeleteBuffer later on to free the buffer after usage In order to be able to access contents at the memory address passed by the target DLL in case that the address is not used as a handle exclusively but also use as a memory buffer for instance as in the USBAXLA example two
16. e VisualStudio 2010 Express Edition but of the 2012 and 2013 version Please note that if you are installing the additional service pack for VisualStudio 2010 from http www microsoft com de de download details aspx id 23691 which we recommend especially if you experience some problems after installing the SDK this will accidentally remove the 64 bit compiler again You ll then have to reinstall it using the hotfix that Microsoft provided under http support microsoft com kb 2519277 en us for this installation bug If you re planning to distribute wrapping DLLs to some other people like colleagues or customers you also need to install the installer generator InnoSetup from http www jrsoftware org isinfo php After installing DLLWrapper with the respective option checked you ll find some real world examples in the public document folder in the directory DLL Wrapper Examples simply follow the link created in the start menu We have installed those files in this directory so that you or other users are able to build the examples even without admin rights At the moment the following examples are provided Example Description Web site K8055D Wrapper to access Velleman s K8055D http Awww velleman eu VM110 USB Multi I O Board from 64 bit products view id 404998 PCSGU250 Wrapper to access Velleman s PCSGU250 http www velleman eu oscilloscope generator from 64 bit products view id 37 7622 USBAXLA Wrapper to
17. first have to install some necessary third party build tools that DLLWrapper is relying on All of those tools are available free of charge but due to legal reasons we weren t able to bundle them with DLLWrapper so you have to install those tools manually before System requirement for DLLWrapper is a PC with a 64 bit Windows operating system like Windows Vista Windows 7 or Windows 8 it can t be used on a 32 bit Windows operating system As it is deprecated we don t support Windows XP 64 bit too At first you should install a version of the free VisualStudio Express Edition from Microsoft s web site http www visualstudio com downloads download visual studio vs you can use either the 2010 version which is the last version that can be installed under Windows Vista or the 2012 or the 2013 version of VisualStudio Express If you already have other editions of VisualStudio Professional Premium Ultimate installed they should work too but we can t guarantee that If you ve installed the 2010 version of VisualStudio Express you ll have to install the Windows SDK 7 1 from Microsoft s web site _http www microsoft com en us download details aspx id 8279 too or if you prefer an ISO lmage from http www microsoft com en us download details aspx id 8442 in which case you ll need the image GRMSDKX_EN_DVD iso for the 64 Bit SDK as it includes the needed 64 bit C C compiler and some other tools like the MIDL compiler which are not part of th
18. ll be mapped to the invocation of a COM object method passing the barrier between the 64 bit process environment of the host application and the 32 bit process environment of the target DLL by executing the call in the environment of the wrapper EXE as shown below n a 64 bit host gt a lt target gt _proxy dll 64 bit environment 4 lt target gt _64 dll 32 bit environment lt target gt _stub dll 14 gt lt target gt _32 exe a gt lt target gt dll For the rest of this document it is assumed that you re able to read and possibly write C header files if you re not at home in this you should find someone who is We d like to emphasize that this tool is designed for experts with some programming experience as deepened understanding of the Windows operating system as well as procedure call and parameter passing mechanism are vital to achieve a smoothly running wrapper DLL Attention as it is not possible to guarantee for any of a literally infinite number of combinations that DLLWrapper will generate error free resulting software you as the user are responsible for testing the correct behavior of the generated wrapper DLL in all of your use cases we can t take that off your shoulders sc_dll_wrapper_manual doc 1 12 20 02 2014 Es DLL Wrapper 32 bit 64 bit SoffComponents industrial quality software Installation Before installing and using DLLWrapper you
19. n point of time unions can only be passed as chunks of memory that will be copied from one address space to the other without further marshalling This implies that using unions with pointers in it will not work as the memory the pointer is pointing to is itself not copied and the value of the pointer will be of no meaning in the other address space This is only a minor limitation as union are rarely used as DLL function parameters Bitfields Bitfields are passed from one address space to the other simply by copying the contents of the memory cells they occupy There is no guarantee that the bit order is compatible in this case normally it should be but using bitfields as DLL function parameters is no good idea anyway because there placement is dependent on the programming language and even on the compiler version use to build the original DLL Troubleshooting If you experience trouble with the installation of DLLWrapper please read the installation section of this manual carefully as it includes some necessary preconditions for a successful installation of the tool Especially you should be sure that you ve installed all required external tools before installing DLLWrapper itself If you encounter problems during the building of a wrapper DLL please read the messages in the log tab of the GUI or on the console output carefully as they may give you some vital hints on what s going wrong Typical sources for problems during the build of a wra
20. ompiler 0 ower i E ee File License Help man tog SoftComponents DLL Wrapper ind software wrapperTestDLL 32 idl 64 bit Processing C Program Files x86 Microsoft SDKs Windowss v7 0A Indude unknwn idl unknwn idl 64 bit Processing C Program Files x86 Microsoft SDKs Windowss v7 0A Indude wtypes idl wtypes idl 64 bit Processing C Program Files x86 Microsoft SDKs Window s v7 0A Indlude basetsd h basetsd h 64 bit Processing C Program Files x86 Microsoft SDKs Windowss v7 0A Indude guiddef h quiddef h dildata c wrapperTestDLL32_i c wrapperTestDLL32_p c Generating Code Creating library f Test Wrapper_wrapperTestDLL32 Wrapper_proxy wrapperTestDLL32_proxy lib and object f Test Wrapper_wrapperTestDLL32 Wrapper_proxy wrapperTestDLL32_proxy exp Info 11105 Starting dil generation wrapperTestDLL32_64 c wrapperTestDLL32_i c Generating Code Creating library f Test Wrapper_wrapperTestDLL32 Wrapper_dil wrapperTestDLL32_64 lib and object f Test Wrapper_wrapperTestDLL32 Wrapper _dll wrapperTestDLL32_64 exp Info 11108 Starting generation of reg and unreg batch file m Info 11106 Coping the products to output path wrapperTestDLL32_reg c Activating logging eT f Wrapper success X Under the File menu you ll find two items to clear all settings or the reload the last settings that were stored when closing the tool the last time
21. or wrapping the specific DLL interface that you need Please note however that we typically won t be able to test the wrapping DLL in any way as we usually would need more than only the DLL to wrap but also the complete software and or hardware environment in which the DLL is supposed to run for this Therefore the test of the wrapping DLL is never part of our wrapping service but your responsibility if you ll find bugs during your test which can t be ruled out because no tests can t be run by us and inform us accordingly we ll provide a fixed version of the wrapping DLL as part of the wrapping service until it is tested error free by you Finally please be aware that it might not be possible to wrap all DLL functions transparently see the chapter Limitations for some explanation In such a case we ll try to provide the best possible work around sc_dll_wrapper_manual doc 12 12 20 02 2014
22. pper DLL are wrong path entries made either during the installation or during the build or missing read and write access rights on selected folders If you experience trouble when trying to use a wrapper DLL you should first check that the build wrapper DLL has actually been placed in a folder were it can be found by the host application if not the host application should issue a warning that for instance the file lt target gt _64 dll could not be located If you re getting error message boxes from the wrapper DLL like CoCreatelnstance failed with error 800 you might have forgotten to register the COM objects using the lt target gt _reg bat batch file which requires admin rights and will fail without further notice if you don t have them If you still have problems building or using a wrapper DLL the tool provides some helpful diagnostic features that you can use to solve even complicated issues Verbose mode The command line version of DLLWrapper has a command line switch V to activate verbose mode in which all command invocations are echoed to the standard console output If you re already using the command line version of DLLWrapper simply add this option to your command line and hopefully you ll be able to find out which external tool is not running as it should and why If you re using the GUI version of DLLWrapper you ll find the command line information which is used by the GUI at the beginning of the messages displaye
23. roblem Be aware that there is no size limit for the logging file right now which means that it will grow and grow until being deleted manually or until there is no space left on the storage device Service and Support If the troubleshooting information above didn t help we ll provide 90 days e mail support with 48 hours maximal response time for all customers that purchased a full license of DLLWrapper regarding installation and building issues after date of purchase that means you can get quick free of charge help if DLLWrapper is not installing or running as it should Please understand that we can t provide support of any kind for the free of charge trail version of DLLWrapper However we can NOT provide free support for wrapping a certain 32 bit DLL that you like to call from a 64 bit host of course as there are trillions of possible use cases which are all individual and might lead to specific problems that have to solved individually too For such cases or if you simply don t like to do the wrapping by yourself we provide a wrapping service for an additional fee which will build a wrapper package for a DLL provided by you according to your needs as long as you can provide the necessary header file and or documentation to the DLL as well If you re interested to make use of this wrapping service please contact us under service DLLWrapper com and attach some files like header files or documentation that ll allow us to make a quote f
24. s to memory chunks returned by a DLL function are assumed to be pointing to statically allocated memory inside the original function Especially if the functions described in your header file are using pointers to pass arrays from and to the host application with types different from char and unsigned char which is quite common praxis in C you ll have to modify the function prototype in order to provide the correct information for DLLWrapper you have to get DLLWrapper to use assumption 5 instead of 4 In case you know from the DLL documentation that function foo is called with an integer array with a fixed number of 16 elements you ll have to change void foo int tab into void foo int tab 16 In case an array has a variable size depending on some other function parameters you can change void foo int len int tab into void foo int len int tab len In the rare case that the size of an array is neither fixed nor can be determent by other function parameters a wrapping of this function is not possible with DLLWrapper If you don t need the function anyway you can simply delete it from the header file otherwise you ll have a problem now For the sake of efficiency it is recommended to add the const modifier to pointer function parameters that are knowingly not modified by the called function You should check your DLL documentation to extract this information as this will reduce the unavoidable overhand impose
25. t s set to a larger value an access violation might be the result In general it s better to rewrite the function prototype to unsigned char bar void 512 in case the buffer is 512 bytes in size for instance This is mandatory anyway for functions returning arrays of other types than char and unsigned char as DLLWrapper will assume that a pointer returned by the function will only point to a single type instance by default If a DLL function is actually returning dynamically allocated memory the approach described in the section above has to be used and the pointer values should be passed unchanged directly from one a address space to the other as they are used as handles too In case such memory chunks were allocated from the default Windows process head or a DLL function expects a memory chunk that has been allocated on the default process heap and will free it during the function call two additional generic function will always be generated into the wrapping DLL which can be used to directly allocate and free memory on the default process heap in the address space of the target DLL unsigned long lt target gt AllocMem unsigned long size void lt target gt FreeMem unsigned long addr sc_dll_wrapper_manual doc 10 12 20 02 2014 Es DLL Wrapper 32 bit 64 bit SoffComponents industrial quality software Unions As there is usually no generic way to find out which element of a union is the valid one ata give
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