R help - Oct 2003 - Acces violation ???

Dear R-listers,

I have created a "dll" and I call it from a R function. However R
stops and
shows the message:

"Unhandled exception in Rgui.exe (R.DLL): 0xC0000005: Access
Violation"

I get this error in other situations and I solved it verifying that all
parameters are called fine. (e.g., double precision -> as.double, integer
->
as.integer,...). I have verify this. Then, I have tried to debug Fortran
program in order to verify why (or where) function doesn't work.
Surprisingly the subroutine arrives until the end.

What is happening?

Thank you in advance

Juan

On Wed, 1 Oct 2003 16:17:42 +0200, "Juan Ramon Gonzalez"
<jrgonzalez at ico.scs.es> wrote :
>Dear R-listers,
>
>I have created a "dll" and I call it from a R function. However R
stops and
>shows the message:
>
>"Unhandled exception in Rgui.exe (R.DLL): 0xC0000005: Access
Violation"
>
>I get this error in other situations and I solved it verifying that all
>parameters are called fine. (e.g., double precision -> as.double, integer
->
>as.integer,...). I have verify this. Then, I have tried to debug Fortran
>program in order to verify why (or where) function doesn't work.
>Surprisingly the subroutine arrives until the end.
>
>What is happening?
Most likely it's a clash of calling conventions.  R uses the
"cdecl"
calling convention, which means it expects to clean up the stack after
a call.  If your Fortran uses the more common "stdcall" convention, it
will have already removed parameters from the stack.  Removing things
twice is bad.

I've got a web page
<http://www.stats.uwo.ca/faculty/murdoch/software/compilingDLLs/> that
gives some advice on writing DLLs for R.  It also gives pointers to
the existing documentation in the R manuals, etc.

Duncan Murdoch