creating dll for autoit

[dantay9]

Since the use of this dll is for autoit and I know there are some c++ experts here, I will ask here first. I am trying to put _PreviousPrime from here into a dll. I found an example on the internet with everything created already; all I had to do was change the function to what I wanted. There is something going wrong with the "long long" part of my function. At the very beginning of my function, I am returning the same value as the parameter. The return value here is a negative number so it is looping back on itself like it would if you assign a big number to an int. I also made sure the dll file was in the correct spot. I don't know much about c++, so can someone help me out a bit?

Here is the autoit code:

$a = DllCall(@ScriptDir & "\example1.dll", "int64", "previousprime", "int64", 9223372036854775783)
ConsoleWrite(@error & @CRLF)
_ArrayDisplay($a)

Here is the code for example1.cpp:

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#include "stdafx.h"
#include <math.h>

BOOL APIENTRY DllMain( HANDLE hModule, 
    DWORD ul_reason_for_call, 
    LPVOID lpReserved
                 )
{
    return TRUE;
}

long long _stdcall previousprime(long long s_number)
{
    return (long long) s_number; // I am returning the parameter so it should return whatever was entered

    if(s_number == 3)
        return 2;
    if(s_number < 6)
        return 3;
    if(s_number < 8)
        return 5;

    long long i;
    long long number = 0;
    if(s_number % 2 == 0)
        number = s_number + 1; //make the number odd

    while(true)
    {
        number -= 2;
        if(number % 3 == 0)
            number -= 2;
        long long s_limit = (long long) sqrt((double) s_number);

        for(i = 5; i <= s_limit; i+= 2)
        {
            if(number % i == 0)
                break;
        }
        if(s_limit < i)
            return number;
    }
    return -1;
}

Here is example1.def:

LIBRARY example1

EXPORTS

previousprime @1

There are other files, but I think that is all you need. If you need other files, I will post them.

Edited October 22, 2009 by dantay9

[Authenticity]

You didn't specify you're exporting the function using the __declspec keyword.

Edit: Yeah, I see the problem, it's definitely not __declspec.

What is more funny is that sending it 2^63-1 results in -(2^63) and the return value is 2^31...

Edited October 22, 2009 by Authenticity

[dantay9]

OK. Read through that page and tried a bit out, but it didn't work. I tried putting "__declspec(dllexport)" in front of the function and also tried putting "__declspec(dllexport) long long _stdcall test(long long s_number);" right after the includes. Neither of these worked. Can you provide me with an example?

Edit: Just saw your edited post. Do you have any other ideas? Here are are the files before I built the dll.

Edited October 22, 2009 by dantay9

[dantay9]

I found out that if I use DllCall(@ScriptDir & "\example1.dll", "int", "previousprime", "int64", 65), it seems to work. Of course it only works for numbers below 2 billion though. But it works more than the original. Don't know why.

Edited October 22, 2009 by dantay9

[GEOSoft]

This seems to be the day for people to post non-autoit support questions in the AutoIt General Help and Support forum.

[Authenticity]

I see that using a MessageBox you can confirm that the dll receives the true value but when the value is returned something is buggy, I'm tending to think it's something about how AutoIt expects the return value. Not every compiler return the value as EAX:EDX so it's hard to predict.

Example:

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LONGLONG __stdcall previousprime(LONGLONG s_number)
{
    TCHAR szBuff[80];

    swprintf(szBuff, _T("%lld"), s_number);
    MessageBox(NULL, szBuff, _T("Test"), MB_OK);
    return s_number; // I am returning the parameter so it should return whatever was entered

    if(s_number == 3)
        return 2;
    if(s_number < 6)
        return 3;
    if(s_number < 8)
        return 5;

    long long i;
    long long number = 0;
    if(s_number % 2 == 0)
        number = s_number + 1; //make the number odd

    while(true)
    {
        number -= 2;
        if(number % 3 == 0)
            number -= 2;
        long long s_limit = (long long) sqrt((double) s_number);

        for(i = 5; i <= s_limit; i+= 2)
        {
            if(number % i == 0)
                break;
        }
        if(s_limit < i)
            return number;
    }
    return -1;
}

..don't forget to include stdio.h and tchar.h.

What I think you can do right now is to return a pointer or require additional parameter which will be something like:

$tagLargeInteger = DllStructCreate('int64')

; Or
$tagLONGLONG = DllStructCreate('int;int')

; Or
$tagInt64 = DllStructCreate('int[2]')

[dantay9]

Thank you for your help. I will try that out.

[Zedna]

I used extern "C" __declspec(dllexport)

in one of my DLL files which I called from Autoit.

So try to add: extern "C"

[Authenticity]

It might be the problem, Zedna.

But even without checking to see first, I've made a test using only AutoIt's number system and ConsoleWrite() types representations. If the third result is what dantay9 is getting then something is not correct about how EAX:EDX is expected or restored back to the original meaningful value:

ConsoleWrite(9223372036854775807 & @CRLF) ; 0x7FFFFFFFFFFFFFFF
ConsoleWrite(2147483647*4294967296+4294967295 & @CRLF) ; 0x7FFFFFFF << 32 | 0xFFFFFFFF
ConsoleWrite(4294967295*4294967296+2147483647 & @CRLF) ; 0xFFFFFFFF << 32 | 0x7FFFFFFF

[monoceres]

extern "C" is needed otherwise the exported name would be scrambled beyond recognition. Also, if you use stdcall (which is better than cdecl) your functions names will be decorated. For example int test(int) will be test@4 and int test(int,int) would be test@8 (it's simply the parameter size in bytes after the @ sign, it's a linker thing). You can avoid this with a definition file in your project.

Quck guide here to compiling and using dll.

http://www.autoitscript.com/forum/index.php?showtopic=87287&view=findpost&p=626480

[dantay9]

I did a little more testing and found out that it seems to only be a problem when "int64" is used as a return value when calling the dll function in autoit. From what I can conclude, there isn't anything wrong with the c++ function, it is autoit's dllcall. There could be something wrong with the compiling of the dll and that might be what is being discussed now. I can't be of much support because all this talk is WAY over my head.

Edit: returning an unsigned long works

Edited October 22, 2009 by dantay9

[Authenticity]

I think that you should submit a bug track because there is a problem when the return value is int64 and I think that you can assume what is the problem. AutoIt swaps the dwords on function. Take this for example:

example.dll

extern "C"{
    LONGLONG __stdcall test(LONGLONG val)
    {
        LONGLONG temp = (((val & 0xFFFFFFFF) << 32) | (val >> 32));

        return temp;
    }
}

The code is built without any warnings and is perfectly correct. Also, a .def module file was added to export the function without name mangling and the result in AutoIt is of course, LO_DWORD becomes HI_DWORD, vice versa.

$a = DllCall(@ScriptDir & '\example.dll', 'int64', 'test', 'int64', 9223372036854775807)
If Not @error Then ConsoleWrite($a[0] & @CRLF)

[dantay9]

I think it would be better if you were to submit the bug track because you know a lot more about this than I do. I have only been using c++ for a week and a half.