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digitalmars.D.learn - htod problems

reply Scott <sas4z yahoo.com> writes:
I'm currently trying to access some functions in the cards.dll library from a D
library.  I'm an ok programmer but not an expert by any means.  

A explanation of the C interfaces are at this URL.  
http://www.catch22.net/tuts/cardtut.asp  

Essentially they provide a cards.h example and I tried to run htod on that
file.  But I was getting a few errors due to some fancy function pointer.  

I also have used implib to convert cards.dll to cards.lib.  Essentially how can
I properly make the function calls from a D file?
Oct 03 2007
parent reply Gilles G. <schaouette free.fr> writes:
working with DLLs using D is simple:
I will make a simple example for this function:
BOOL WINAPI cdtInit (int *width, int *height)

if you want to use that function in a D program, you have to declare its
prototype as extern(Windows) (because it use the WINAPI). For example:
extern(Windows) alias int function(int*,int*) CDTINIT;
(note: the BOOL type was replaced by int because I guess this BOOL type is not
equivalent to D's bool)

Then, in the main programm you must load the DLL before using it:
import std.c.windows.windows;
/* some more imports and external defines */
int main()
{
        HMODULE h;     // the DLL handle
        h = LoadLibraryA("StepArray.dll");
        /*  do something */
        FreeLibrary(h);
        return 0;
}

Now, in order to access the function, you have to know how the names exported
by the DLL are "mangled" by the compiler. A simple way to know this is to use
the program "Dependency walker" that you will find easily on the internet. for
example, the mangled name for cdtInit could be: _cdtInit 8 or just cdtInit.
Once you know the name for the function you can get an instance of the function
by using:
auto cdtInit = cast(CDTINIT) GetProcAddress(h,"_cdtInit 8");

And you can use cdtInit just as a function, for example:
int width, height;
auto returnCode = cdtInit(&width,&height);

Good luck!

--
Gilles

Scott Wrote:


 I'm currently trying to access some functions in the cards.dll library from a
D library.  I'm an ok programmer but not an expert by any means.  
 
 A explanation of the C interfaces are at this URL.  
 http://www.catch22.net/tuts/cardtut.asp  
 
 Essentially they provide a cards.h example and I tried to run htod on that
file.  But I was getting a few errors due to some fancy function pointer.  
 
 I also have used implib to convert cards.dll to cards.lib.  Essentially how
can I properly make the function calls from a D file?  
 
 #ifndef _CARDS_INCLUDED
 #define _CARDS_INCLUDED
 
 typedef BOOL (WINAPI *pfcdtInit)(int *, int *);
 typedef BOOL (WINAPI *pfcdtDraw)(HDC, int x, int y, int card, int type, DWORD
color);
 typedef BOOL (WINAPI *pfcdtDrawEx)(HDC, int x, int y, int dx, int dy, int
card, int type, DWORD color);
 typedef BOOL (WINAPI *pfcdtAnimate)(HDC hdc, int cardback, int x, int y, int
frame);
 typedef void (WINAPI *pfcdtTerm) (void);
 
 #define ecbCROSSHATCH  53
 #define ecbWEAVE1      54
 #define ecbWEAVE2      55
 #define ecbROBOT       56
 #define ecbFLOWERS     57
 #define ecbVINE1       58
 #define ecbVINE2       59
 #define ecbFISH1       60
 #define ecbFISH2       61
 #define ecbSHELLS      62
 #define ecbCASTLE      63
 #define ecbISLAND      64
 #define ecbCARDHAND    65
 #define ecbUNUSED      66
 #define ecbTHE_X       67
 #define ecbTHE_O       68
 
 #define ecsCLUBS    0
 #define ecsDIAMONDS 1
 #define ecsHEARTS   2
 #define ecsSPADES   3
 
 #define ectFACES		0
 #define ectBACKS		1
 #define ectINVERTED		2
 
 #define MAKE_CARD_VALUE(face, suit) (face + suit*4)
 


#endif
Oct 04 2007
parent Gilles G. <schaouette free.fr> writes:
Of course you should read:

         h = LoadLibraryA("cards.dll");


sorry for the typo...
Oct 04 2007