Thanks! Doing the (make-cdata struct-mosquitto_message* message) as well as changing cdata-ref to cdata*-ref works fine.
Obviously, what someone should do is to write a nice schemey interface on top of what you get with (ffi mosquitto). Best regards, Mikael On Fri, Nov 1, 2024 at 3:05 PM Matt Wette <matt.we...@gmail.com> wrote: > And one more thing. There is a manual for cdata. There is a link on > this page > > https://www.nongnu.org/nyacc/ > > > On 11/1/24 6:37 AM, Matt Wette wrote: > > I got this wrong. Sorry! This is it. What I gave previously was > > the old fh syntax. > > > > (msg (make-cdata struct-mosquitto_message* message)) > > > > > > > > On 11/1/24 6:32 AM, Matt Wette wrote: > >> assuming message is a Guile pointer: > >> > >> (define (receive-message mosq obj message) > >> (let ((msg (make-struct-mosquitto_message* message)) > >> (size (cdata-ref msg '* 'payloadsize)) > >> (payload (cdata-ref msg '* 'payload)) > >> (pointer->string payload size))) > >> > >> > >> On 10/31/24 4:49 PM, Mikael Djurfeldt wrote: > >>> Hi Matt, > >>> > >>> This is very nice indeed! :-) > >>> > >>> I got a small client working, but I found the unpacking of values in > >>> the message callback function a bit cumbersome. I now have: > >>> > >>> (define (pointer->struct-mosquitto_message pointer) > >>> (let* ((size (ctype-size struct-mosquitto_message)) > >>> (bvec (pointer->bytevector pointer size))) > >>> (Xcdata-ref bvec 0 struct-mosquitto_message))) ;The only > >>> way I found that worked! :) > >>> > >>> (define (receive-message mosq obj message) > >>> (let* ((message (pointer->struct-mosquitto_message message)) > >>> (payload (cdata-ref message 'payload)) > >>> (size (cdata-ref message 'payloadlen)) > >>> (payload (pointer->string payload size))) > >>> (display payload) > >>> (newline))) > >>> > >>> Is there some more convenient/right way to do that? > >>> > >>> Best regards, > >>> Mikael > >>> > >>> On Thu, Oct 31, 2024 at 1:02 PM Matt Wette <matt.we...@gmail.com> > >>> wrote: > >>> > >>> On 10/31/24 1:48 AM, Ricardo G. Herdt wrote: > >>> > Hi, > >>> > > >>> > never did it myself, but you can create some bindings to > >>> libmosquitto > >>> > for your usecase. There are bindings for chicken, one can take > >>> some > >>> > inspiration from there: > >>> http://wiki.call-cc.org/eggref/5/mosquitto#api > >>> > > >>> > Regards, > >>> > > >>> > Ricardo > >>> > > >>> > Am 31.10.2024 03:24 schrieb Alan Wedel: > >>> >> I have been working on a controller that uses a > >>> microcontroller to > >>> >> read some sensors and publish their data to a mqtt broker. I > >>> would > >>> >> like to have a guile program subscribe to the mqtt broker and > >>> log the > >>> >> sensor readings to a file. Is there anyone using guile with > >>> mqtt like > >>> >> this? If so, how are you doing it? > >>> > > >>> > >>> Here is a dot-ffi file for mosquitto using nyacc: > >>> > >>> (define-ffi-module (ffi mosquitto) > >>> #:pkg-config "libmosquitto" > >>> #:include '("mosquitto.h")) > >>> > >>> > >>> I just uploaded nyacc-2.01.2, needed to compile above. > >>> > >>> refs: > >>> https://savannah.nongnu.org/projects/nyacc > >>> https://www.nongnu.org/nyacc/nyacc-fh-ug.html > >>> > >>> Matt > >>> > >>> > >>> > >>> > >>> > > > > > >
