hi all,

i am pretty new to Python(a very new to this forum). have been programming in C & C++.

i have a DLL written in C which i need to use. i would like to access it through Python instead of using Visual C++.

i am having a problem with this though. i hope someone here can help.

lemme start with my DLL definition:

#ifndef DLL_ABC_H
#define DLL_ABC_H

//Exported functions
#ifndef DLL_ABC
   #ifdef __BORLANDC__
      #define DLL_ABC   _export 
   #else
      #define DLL_ABC __declspec(dllexport) __stdcall 
   #endif
#endif

extern "C"
{
   //Version of the DLL
   extern void DLL_ABC Info_Version_ABC(char *sVersion);

   extern BYTE DLL_ABC B_ABC_Function01(BYTE *pbParam1);

   extern BYTE DLL_ABC B_ABC_Function02(BYTE * pbParam2,BYTE *pbParam3);

   extern BYTE DLL_ABC ABC_Function03(char * sFileNameIn, char * sFileNameOut,BYTE * pbParam4);

}
#endif

basically, its the byte pointers that are causing the problem. i need to work in hexadecimal here.
(param 4 is to be read in. Funtions 01 and 02 set params that wld be used by function 3 to calculate param4.)
example of use of DLL is as such:

BYTE pbParam4[16];
BYTE pbParam1[16]={0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F};
BYTE pbParam2[16]={0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F};
BYTE pbParam3[16]={0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F,0x0F};

B_ABC_Function02(pbParam2,pbParam3);
B_ABC_Function01(pbParam1);

ABC_Function03("FileIn.txt", "FileOut.txt",pbParam4);

in my Python script, i have the following:

abc = ctypes.windll.DLL_ABC

p2 = 0x0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F
p3 = 0x0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F
byte = ctypes.c_byte()
byte = abc.B_ABC_Function02(ctypes.byref(ctypes.c_void_p(p2)), ctypes.byref(ctypes.c_void_p(p3)))

p1 = 0x0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F
byte = abc.B_ABC_Function01(ctypes.byref(ctypes.c_void_p(p1)))

p4 = 0x0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F
byte = abc.Function03(ctypes.byref(ctypes.c_char_p(FileIn)), ctypes.byref(ctypes.c_char_p(FileOut)), ctypes.byref(ctypes.c_void_p(p4)))

i suppose call to functions 01 and 02 are OK. however, at Function03 call, i get an error that says "error: (10054, 'Connection reset by peer')".

i am then brought to Stream.py and a statement in "def read(self, count):" is highlighted. the statement is "buf = self.sock.recv(count)".

i believe the filenames are alright. thats pretty simple.

any advice? i'm stuck here and if this cant be solved, then i will have to use this DLL in C++.

thanx in advance.

Where are your FileIn and FileOut strings?

hi,

thanx for your interest.

FileIn and fileOut string are read in from commandline arguments. they were the problem afterall.

byte = abc.Function03(FileIn, FileOut, ctypes.byref(ctypes.c_void_p(p4)))

the above line works. but it looks like the p1 - p3 i'm sending in and the p4 i'm reading out are not correct. the content of FileOut and p4 are not as expected.

perhaps my passing or references are not good.

i tried this, result is different but not as expected either.

byte = abc.B_ABC_Function02(hex(p2), hex(p3))

i tried this, result is different but not as expected either.

byte = abc.B_ABC_Function02(hex(p2), hex(p3))

Do you need to convert the returned value to hex perhaps??
i.e.

byte = hex( abc.B_ABC_Function02(hex(p2), hex(p3)) )

The above code should set the value of byte to be a hexadecimal representation of the value returned by your abc.B_ABC_Function02() call.
Does that give you the expected result?
Jas.

hi,

i'm sorry, but it looks like i wasn't clear enough.

my app is such that i use functions 01 & 02 to set params in the DLL. then i use function 03 to process the input file(FileIn). and i will get an output file(FileOut) and p4 which is used with the output file. the return from all the functions are just the status.

now, what i find is that the output file and p4 has not been processed as expected. i suspect this is due to incorrect settings of p1 - p3. most likely because i am not sending them in correctly.

as you can see from the example of use i have posted earlier, using a BYTE array in C/C++ works fine with the DLL. if only i could define this in Python.

hi all,

solution was quite simple actually. i had to create a 16 byte BYTE array and then pass it thru DLL function call.

to do that i had to define:
sixteen_bytes = ctypes.c_ubyte * 16
array = sizteen_bytes(0x0F, 15, 15... 15)

problem solved! :)