ctypes, function pointers and a lot of trouble
nick at craig-wood.com
Wed Jun 4 16:30:21 CEST 2008
Matt <mr.edel at gmx.at> wrote:
> Hm, thanks, now I can access my data in the functions and also write
> them but the program keeps terminating right at the point when the
> "open" function finishes. Unfortunately everything closes and I get no
> error messages.
> I did some additional work in the meantime and changed my code so it has
> the correct datatypes now:
> def pystreamopen (contextH, mode, pErr):
> print "opening..."
> print contextH.contents.dwBufferSize #just to check the structure
> print mode #tells about what the DLL wants to do with this stream
You program is crashing somewhere after here since mode is printed but
nothing else is
> contextH.contents.mode = c_byte(5) #5=Permission to read and write
> contextH.contents.lPos = c_uint(0) #start position
> print pErr.contents
> pErr.contents = c_uint(0)
Try commenting out these lines and see if it works, then uncomment one
at a time.
Also is that supposed to be returning something?
> Anyway, meanwhile decided to try a different approach. Maybe I have
> more luck by having the function write the data directly into a file on
> the HDD.
> Doe anyone know how to translate the following into Python/ctypes?
> I googled quite a lot before but all topic-related I found was my own
> posting here in this NG :S
> pFilStrm->hFile = CreateFile( pFilStrm->szFileName,
> dwDesiredAccess, dwShareMode, NULL,
> NULL );
use os.read os.write and os.open which will give you OS handles rather
than python file objects, ie I think these are a fairly direct
interface to CreatFile etc (but I could be wrong - I'm not a windows
Nick Craig-Wood <nick at craig-wood.com> -- http://www.craig-wood.com/nick
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