Re: [Help-smalltalk] C Callouts issue

[Gwenaël Casaccio]

On 10/07/2013 08:15, Stephen Woolerton wrote:
> > OKay, so you would like to have something like a intOut.. or does
> > CInt help here? Sorry, I am guessing. Or something like #selfSmallalk?
> >
> >     holger
> Thanks holger.
>
> I had two issues in the last post.
> One was a typo, the call to initializeNote was missing a # in the 
> definition, i.e. #(#self)
Hi,

You need to pass a CUInt object and not an integer since the function 
expect a pointer.

| note retVal |
retVal := CUInt value: 0.
note := CNote newBlankNote: retVal.

Gwen

> However, I am still working on how to pass a "pointer to an unsigned 
> int" as a C callout. The page 
> http://www.gnu.org/software/smalltalk/manual/gst.html#C-data-types 
> shows how to pass a pointer to a scalar when in a struct, e.g. 
> (#example (#ptr #long)).
> So I changed my script to have a similar definition:
>
>   CNote class >> newBlankNote: retVal [
>      <cCall: 'newBlankNote' returning: #{CNote} args: #((#ptr #uint)>
>   ]
>
> And here is the result when the library is called... (the first two 
> lines come from printf statements inside the C library. The second 
> line shows that the pointer was not actually passed into the library, 
> it is nil)
>
>  Inside newBlankNote: Size in bytes allocated to struct 'Note': 8
>  Inside newBlankNote: resultCode pointer: [(nil)]
> ./ccall2.st:30: Aborted
> ./ccall2.st:30: Error occurred while not in byte code interpreter!!
> /usr/local/lib64/libgst.so.7(+0x71ca7)[0x7f8d8d996ca7]
> /lib64/libc.so.6(+0x37c50)[0x7f8d8ceb2c50]
> /lib64/libc.so.6(gsignal+0x35)[0x7f8d8ceb2bd5]
> /lib64/libc.so.6(abort+0x17b)[0x7f8d8ceb404b]
> /usr/local/lib64/libgst.so.7(+0x2c9bb)[0x7f8d8d9519bb]
> /usr/lib64/libsigsegv.so.2(+0xe7c)[0x7f8d8cc77e7c]
> /lib64/libc.so.6(+0x37c50)[0x7f8d8ceb2c50]
> /home/stephenw/devel_gst/ccall2/bug1/libccall2.so(newBlankNote+0x74)[0x7f8d8b7196d0] 
>
> /usr/lib64/libffi.so.6(ffi_call_unix64+0x4c)[0x7f8d8ca74ecc]
> /usr/lib64/libffi.so.6(ffi_call+0x19d)[0x7f8d8ca7489d]
> Aborted
>
> Regards
> Stephen
>
>
>
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