searching: example of C extension implementing port

searching: example of C extension implementing port

[Marco Maggi]

Ciao,

  is there a sample extension implementing an input/output
channel?

I'm thinking of a memory channel (not an interface
to a file or hardware port), something like the string
port; is the channel API of Guile worth learning for this,
or is it better to write something of my own?

I only need the open/close/read/write/end operations, no
events, no seek.

--
Marco Maggi

"They say jump!, you say how high?"
Rage Against the Machine - "Bullet in the Head"



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Re: searching: example of C extension implementing port

[Ludovic Courtès]

Hi,

"Marco Maggi" <marco.maggi-ipsu@poste.it> writes:

> I'm thinking of a memory channel (not an interface
> to a file or hardware port), something like the string
> port; is the channel API of Guile worth learning for this,
> or is it better to write something of my own?

Perhaps you can look at the file ports or string ports in Guile itself
(fports.c and strports.c).  Guile-gnome contains an example, too, but I
couldn't find it.

Hope this helps,
Ludovic.


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Re: searching: example of C extension implementing port

[Kevin Ryde]

"Marco Maggi" <marco.maggi-ipsu@poste.it> writes:
>
> is there a sample extension implementing an input/output
> channel?

You'll have seen the "Soft Ports" node in the manual, it's pretty
straightforward.

> I'm thinking of a memory channel (not an interface
> to a file or hardware port), something like the string
> port; is the channel API of Guile worth learning for this,

If it's for a lot of bytes, then the scheme-level bits will be very
slow (read/write only 1 byte at a time) and you might have to break
out some C.  (Getting that C level bits into scheme would be a good
thing one day.)

> or is it better to write something of my own?

For reading OLE file contents I did my own read func.  But whether
that's good probably depends what and how much other code is going to
use the port.


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Re: searching: example of C extension implementing port

[Marco Maggi]

"user42@zip.com.au" wrote:
>You'll have seen the "Soft Ports" node in the manual,
>it's pretty straightforward.

Yes, it is straightforward with pure Scheme; but I have
to filter a stream of bytes (binary data not strings)
thru a C implemented algorithm.





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Re: searching: example of C extension implementing port

[Marco Maggi]

>"Marco Maggi" <marco.maggi-ipsu@poste.it> writes:
>> If, dunno when, I come up with a simple example channel
>> implementation: is there an "official" place where I can
>> put it?
>I don't think so.  Well, depends on what you mean by
>"official" I guess.  ;-)  And BTW, what do you mean
>by "channel"?

I come from TCL:

* in the TCL world it is known that the sample
  extension is a module in the CVS repository of
  the TCL core project at SourceForge; if one goes
  to the TCL'ers Wiki and does a search he quickly
  finds it;

* in the TCL world a channel is a generalisation
  of Guile ports; not only it does I/O on file,
  sockets and memory (strings), but channels can be
  stacked to do compression, encryption, etc.

With TCL a channel is somewhat complex because: there
is also the event loop to take into account; so simpler
stacking is what I'm trying to do in a C only library and
I would like to build an interface for Guile.

  If someone wants to take a look at what I've done so
far (it is only half written, it is tough to do reverse
engineering):

http://web.tiscali.it/marcomaggi/tmp/gee--alpha--0.1.tar.gz

--
Marco Maggi

"They say jump!, you say how high?"
Rage Against the Machine - "Bullet in the Head"



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