[PD-dev] signal external and IOhannes's tutorial

Adam T. Lindsay atl at comp.lancs.ac.uk
Wed Sep 25 15:13:39 CEST 2002

Hi all.

I've been trying to work through Johannes's useful tutorial on PD
externals. In the signal example, English version, he says:

>Optimization of the DSP-tree tries to avoid unnecessary copy-operations.
>Therefore it is possible, that in- and out-signal are located at the same
>address in the memory. In this case, the programmer has to be careful not
>to write into the out-signal before having read the in-signal to avoid
>overwriting data that is not yet saved.


To me, this is a bit ambiguous (and my German officemate couldn't help
with the lang-de version). Who does the optimization? Does PD optimize
the DSP tree such that it creates in-place operations, and therefore the
programmer must be aware of this happening? Or does it mean that the
programmer has the option of optimizing the DSP tree by doing
computations in place, as long as they do it carefully?

I'm sorry if I come across as pedantic about language. I'm honestly
confused, and the API I'm trying to write a glue to actually encourages
in-place DSP computation. So if there is a way of interfacing with PD in
that way, I'd be really happy.


 Adam T. Lindsay                      atl at comp.lancs.ac.uk
 Computing Dept, Lancaster University   +44(0)1524/594.537
 Lancaster, LA1 4YR, UK             Fax:+44(0)1524/593.608

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