Calling A FORTRAN DLL From Excel & VBA

Using: Windows 8.1 © 2013 64 bit OS, x64-based processor MS Office 2013 x64

Download the example from https://myengineeringworld.net/2014/03/fortran-dll-excel-vba.html

Copy the “Calling A FORTRAN DLL From Excel & VBA.xlsm” to the folder ..\MySample\Release\x64

Open the .xlsm Click on the “Enable Content” button

In VBA window, add “PtrSafe” to both Public Declare… Save and Close

As seen in https://www.silverfrost.com/32/ftn95/ftn95_personal_edition.aspx just downloaded the compiler FTN95 Personal Edition (FTN95PE) version 8.61 from http://www.ftn95.co.uk/ftn95/ftn95-8.61/ftn95_personal.exe

Run 'C:\Program Files (x86)\Silverfrost\FTN95\plato.exe'

File > New > Project: Project Type: Fortran DLL Name: MySample

OK

In “Project Explorer”, right click on “Source Files”, click on “Add New Item”

Type: Free format Fortran file Name: MyCode

And paste the content of the downloaded MyCode.f90 in a new .f95 source file

Configuration: Release Platform: x64

Build > Build

So far so good: “Compiling file: MyCode.f95 C:\Users\BarRErA\Documents\MySample\MyCode.F95(17) : warning 197 - Variable C has been declared but not used C:\Users\BarRErA\Documents\MySample\MyCode.F95(17) : warning 197 - Variable D has been declared but not used C:\Users\BarRErA\Documents\MySample\MyCode.F95(51) : warning 197 - Variable I has been declared but not used Compilation completed with no errors. Linking... Creating dynamic link library C:\Users\BarRErA\Documents\MySample\Release\x64\MySample.dl”

When opening the .xlsm, Excel crashes or a exception is thrown.

“FATAL ERROR > Silverfrost exception handler has failed”

Commenting the FRICTIONFACTOR on the .f95 code, compiling again, then going to Excel > tab Sub > clicking RUN (i.e. running the VBA Sub CallDoubleArray()), it works. The problem is with the function call.

I have no clue about what to do. It is my first contact with FORTRAN, I’m an engineer that wants to translate some thermodynamic calculations from VBA to Fortran.

And I got this log:

'Silverfrost 64-bit exception report on C:\Program Files\Microsoft Office 15\Root\Office15\EXCEL.EXE Wed Apr 29 15:08:57 2020

Unknown exception (c004f012) at address 7ffd8cec908c

Within file KERNELBASE.dll In RaiseException at address 6C In RpcRaiseException at address 51 Within file RPCRT4.dll In RpcRaiseException at address 14 In NdrClientCall3 at address F6A In NdrClientCall3 at address FE Within file sppc.dll In SLUnregisterPlugin at address 993 In SLGetPolicyInformation at address 63 In Ordinal7162 at address 12B8 Within file mso.dll In Ordinal7162 at address 11B4 In Ordinal7162 at address 14C0

RAX = 000000391254e420 RBX = 00000000c004f012 RCX = 00007ffd8ecec750 RDX = 0000000000000000 RBP = 0000000000000003 RSI = 0000000000000000 RDI = 000000391254eaf0 RSP = 000000391254e670 R8 = 000000391254e420 R9 = 00007ffd66dc1438 R10 = 00007ffd8ecfe844 R11 = 000000391254e420 R12 = 0000000000000000 R13 = 0000000000000001 R14 = 000000391254ef28 R15 = 000000391254f228

7ffd8cec908c) mov_q RCX,[c0+RSP]'

You will find some information on using Visual Basic here https://forums.silverfrost.com/Forum/Topic/133 and in ftn95.chm under Win32 platform >Mixed language programming > Calling C/C++ from FTN95 >Calling an FTN95 DLL from Visual Basic.

But this is for 32 bits. If you are working with 64 bit DLLs then you may be in uncharted territory. The only potential useful information I can provide is that 64 bits does not use the STDCALL protocol. 64 bit FTN95 allows the use of this keyword but it is ignored for 64 bits and the protocol reverts to C_EXTERNAL.