marshal complex structures to native C dll

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Hi All,

I have a problem with marshaling complex structures (containing numbers,
strings, arrays of another structures) to native C function in dll.
I have already posted same question to .compactframework thread, but nobody
helped.

main problem is that I have tried all the workarounds I have found in the
Inet but nothing worked...
I tried passing IntPtr, Byte Arrays, Serialisation, even used OpenNETCF, but
all failed.

I have even compiled own C dll (eVC 4.0) with same structures and functions,
and there I
can see what is passed in params and can return needed values. Result - the
structure I pass to the function is empty and the structure I return from
the function is not retrieved to outside (I have same structure that passed
to function with no changes)

any ideas?

I need to do it on VB.NET for Compact Framework

thanks in advance for any help.
Ivan.

--------------------

typedef struct tagACROSS_CLUE {
unsigned int numClue; /* Clue number */
LPCWSTR strClue; /* The clue - clue number not included in the string */
} ACROSS_CLUE;

typedef struct tagACROSS_EXTDATA {
unsigned char extDataSignature[4]; /* Four byte character signature */
unsigned int dataSize; /* Size of extended data in bytes */
char * extData; /* uninterpreted bytes of data */
} ACROSS_EXTDATA;

typedef struct tagACROSS_HEADER {
BYTE bytes[44]; /* Uninterpreted bytes from the header */
} ACROSS_HEADER;

typedef struct tagACROSS_PUZZLE_DATA {
unsigned int struct_size; /* size of the data structure passed in bytes
must be initialized */
unsigned int szAcross; /* Grid size - No. of cells across */
unsigned int szDown; /* Grid Size - No. of cells down */
unsigned int numAClues; /* Total No. of Across clues */
unsigned int numDClues; /* Total No. of Down clues */
int flagsDescr; /* Puzzle flags */
int numCodeSet; /* Character code set used for the puzzle */
unsigned int numPtrSolnKey; /* For saving, if solution is to be locked,
the 4 digit lock key is returned here For reading, this is not used */
LPCWSTR strTitle; /* Puzzle Title */
LPCWSTR strAuthor; /* Puzzle Author */
LPCWSTR strCopyright; /* Puzzle Copyright */
LPCWSTR charsGrid; /* Puzzle Grid with solution */
LPCWSTR strNote; /* Puzzle notepad entry. Max length 1023 characters */
ACROSS_CLUE * cluesAcross;/* Pointer to array of Across clues */
ACROSS_CLUE * cluesDown; /* Pointer to array of Down clues */
unsigned int numExtData; /* Number of extended data structures */
ACROSS_EXTDATA * extDataList; /* Pointer to array of extended data
structures */
} ACROSS_PUZZLE_DATA;

ACLIB_API int ACROSS_InputPuzzle(LPCWSTR filename,

ACROSS_PUZZLE_DATA * puzzleDescriptor);

/* filename - Complete path name of file to read puzzle from */

/* puzzleDescriptor - Pointer to structure that will contain puzzle
data. */
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Re: marshal complex structures to native C dll by Bernhard

Bernhard
Fri Jul 22 15:47:28 CDT 2005

Hello,

I would recommend you to write another custom C dll wich
exports some sort of getters and setters for the structure.

LPWCSTR getTitle_PuzzleData(ACROSS_PUZZLE_DATA* data) {
return data->strTitle;
}

void setTitle_PuzzleDate(ACROSS_PUZZLE_DATA* data, LPWCSTR title) {
data->strTitle = title;
}

One the one hand you've got a great number of DllImports and
on the other a complex structure which has to be marshalled.

hth

On Wed, 20 Jul 2005 16:39:37 +0200, Ivan <ivande@ukr.net> wrote:
> Hi All,
>
> I have a problem with marshaling complex structures (containing numbers,
> strings, arrays of another structures) to native C function in dll.
> I have already posted same question to .compactframework thread, but
> nobody
> helped.
>
> main problem is that I have tried all the workarounds I have found in the
> Inet but nothing worked...
> I tried passing IntPtr, Byte Arrays, Serialisation, even used OpenNETCF,
> but
> all failed.
>
> I have even compiled own C dll (eVC 4.0) with same structures and
> functions,
> and there I
> can see what is passed in params and can return needed values. Result -
> the
> structure I pass to the function is empty and the structure I return from
> the function is not retrieved to outside (I have same structure that
> passed
> to function with no changes)
>
> any ideas?
>
> I need to do it on VB.NET for Compact Framework
>
> thanks in advance for any help.
> Ivan.
>
> --------------------
>
> typedef struct tagACROSS_CLUE {
> unsigned int numClue; /* Clue number */
> LPCWSTR strClue; /* The clue - clue number not included in the
> string */
> } ACROSS_CLUE;
>
> typedef struct tagACROSS_EXTDATA {
> unsigned char extDataSignature[4]; /* Four byte character signature
> */
> unsigned int dataSize; /* Size of extended data in bytes */
> char * extData; /* uninterpreted bytes of data */
> } ACROSS_EXTDATA;
>
> typedef struct tagACROSS_HEADER {
> BYTE bytes[44]; /* Uninterpreted bytes from the header */
> } ACROSS_HEADER;
>
> typedef struct tagACROSS_PUZZLE_DATA {
> unsigned int struct_size; /* size of the data structure passed in
> bytes
> must be initialized */
> unsigned int szAcross; /* Grid size - No. of cells across */
> unsigned int szDown; /* Grid Size - No. of cells down */
> unsigned int numAClues; /* Total No. of Across clues */
> unsigned int numDClues; /* Total No. of Down clues */
> int flagsDescr; /* Puzzle flags */
> int numCodeSet; /* Character code set used for the puzzle */
> unsigned int numPtrSolnKey; /* For saving, if solution is to be
> locked,
> the 4 digit lock key is returned here For reading, this is not used */
> LPCWSTR strTitle; /* Puzzle Title */
> LPCWSTR strAuthor; /* Puzzle Author */
> LPCWSTR strCopyright; /* Puzzle Copyright */
> LPCWSTR charsGrid; /* Puzzle Grid with solution */
> LPCWSTR strNote; /* Puzzle notepad entry. Max length 1023 characters
> */
> ACROSS_CLUE * cluesAcross;/* Pointer to array of Across clues */
> ACROSS_CLUE * cluesDown; /* Pointer to array of Down clues */
> unsigned int numExtData; /* Number of extended data structures */
> ACROSS_EXTDATA * extDataList; /* Pointer to array of extended data
> structures */
> } ACROSS_PUZZLE_DATA;
>
> ACLIB_API int ACROSS_InputPuzzle(LPCWSTR filename,
>
> ACROSS_PUZZLE_DATA * puzzleDescriptor);
>
> /* filename - Complete path name of file to read puzzle from */
>
> /* puzzleDescriptor - Pointer to structure that will contain puzzle
> data. */
Top