[PD-dev] Variable amount of signal inlets and outlets

[Roman Haefeli]

On Sat, 2020-05-23 at 12:57 +0200, Christof Ressi wrote:
> One word of warning about externals with multiple signal
> inputs/outputs (quoting from 
> https://github.com/pure-data/externals-howto#signal-classes):
> "Optimisation 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."
> This is still a bit vague, though, I would rephrase it like this:
> "In this case, the programmer has to be careful not to write into
> *any* out-signal before having read *all* in-signals"

Sounds to me like:

 "In order to be absolutely sure to avoid unnecessary copy operations,
you must perform copy operations."

I'm no C programmer, but I don't see how you can read *all* data before
writing *without* copying it around.

Roman
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