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DllCall in x64 with 'double' and 'string' in parameters list

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When I use DllCall function to call a 64bits dll, I encounter a strange behavior. If the dll has to receive a string in first parameter and a 'double' in second parameter, this 2nd one is NOT received by the called function.

I have done some tests, and :

  • x64 + string + double ==> double NOT received
  • x64 + double ==> double succesfully received
  • x86 + string + double ==> double succesfully received
  • x86 + double ==> double succesfully received
The test dll is compiled with MinGW32 (for x86 dll version) / MinGW64 (for x64 version).

My objective is to use a DLL that is already compiled in x64 and having string+double+others parameters (in this order).

Attached files are a simple example of what is ok/ko. Here's the result of what I get when running the test_double.au3 script:

[font=courier new,courier,monospace]Result
call_float__________ => MyFloatValue_ = 0.005000
call_float_filename_ => MyFloatValue_ = 0.005000 - filename = test
call_double_________ => MyDoubleValue = 0.005000
call_double_filename => MyDoubleValue = 0.000000 - filename = test
call_double_filename => MyDoubleValue = 0.000000 - filename = test[/font]

As you can see, both last result report null value...

Files :

  • test_call.c : source code for the simple dll

  • makefile (rename it to .bat)

  • test_double.au3 : script code to call dll & execute

  • test_double_dll.7z : compiled DLL (if you cannot recompile C to DLL)
Thanks in advance for your help

Best Regards





Edited by jlf

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