Re^2: Correct call for dll with Win32::API

This is the line from the sample C-code:
int HCE300_Read(int TrackNo, char *ReadData);

I have no readable documentation of the dll. The data is read from an usb device. Re-reading the documentation of Win32::API I changed the line to:

my $readdevice = Win32::API->new (
                    'HCE300_API.DLL', 'HCE300_Read','NP','N') or die $
+^E;
if(not defined $readdevice) {
        die "Can't import API HCE_Read: $!\n";
    }
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I am not sure what it does, but it did not help. Perl still crashes.

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Re^3: Correct call for dll with Win32::API
by ikegami (Patriarch) on Dec 04, 2008 at 20:24 UTC

If int HCE300_Read(int TrackNo, char *ReadData); is the prototype, then it uses the default calling convention. It my understanding that's __cdecl for MS compilers. Win32::API uses the __stdcall calling convention since that's what the Win32 API (kernel32.dll, etc) uses.

Argument-passing order Stack-maintenance responsibility

__stdcall Right to left Called function pops its own arguments from the stack

__cdecl Right to left Calling function pops the arguments from the stack

Win32::API expects the DLL function to reset the stack, but the DLL function expects its caller to reset the stack.

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Re^4: Correct call for dll with Win32::API

by walto (Pilgrim) on Dec 04, 2008 at 20:38 UTC

Thanks for your help and patience with my lack of C, but does this mean I can not use Win32::API?

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Re^5: Correct call for dll with Win32::API

by BrowserUk (Patriarch) on Dec 04, 2008 at 20:53 UTC

Do you have dumpbin.exe on your system? If so, could you post the output from the command:

dumpbin /exports HCE300_API.DLL
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Re^6: Correct call for dll with Win32::API

by walto (Pilgrim) on Dec 05, 2008 at 05:40 UTC

Re^7: Correct call for dll with Win32::API

by BrowserUk (Patriarch) on Dec 05, 2008 at 13:48 UTC

Some notes below your chosen depth have not been shown here

Re^5: Correct call for dll with Win32::API

by ikegami (Patriarch) on Dec 04, 2008 at 20:57 UTC

If there's a difference in calling conventions, yes. Unresolvable protocol differences.

It could be a number of other things too.

You have the wrong prototype.
You are using the library in a manner it doesn't expect.
There's a bug in the library.
etc.

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