On Jun 15, 2005, at 1:23 PM, Mathieu Bouchard wrote:
On Wed, 15 Jun 2005, Hans-Christoph Steiner wrote:
So now that there are some people using [hid], I want to ask a
question about how its working for people, specifically about the use
of symbols rather than integers for the event naming scheme (i.e.
"abs" vs. "2"; "rel_rx" vs. "5", etc.). It definitely takes more CPU
power to use symbols, so I have two questions: Do you notice the extra CPU load from [hid]? Do you find the symbolic names useful, versus numbers?I think that as long as integers still can be used, there is no
problem with supporting symbols. I mean I've seen cases where the
enforcing of symbols means having to use [sprintf] all over the place
in a less-than-elegant way.
Integers/floats are not supported in [hid] because that would defeat
one of the main purposes that inspired me to write it: to have a clean,
straightforward API. For example, you probably won't need to use a
lookup table to understand [route abs_x abs_y abs_throttle] but most
people would need it for [route 1 3 14]. I can't think of anytime
where you'd need to use [sprintf] with [hid] data, but please try out
strange, unorthodox configurations and let me know if the symbol scheme
causes problems. Its an experiment, every HID API I have seen uses
integers, but almost all are aimed at people who think in terms of
struct, io_service_t, ioctl, etc.
I am planning on writing [darwinhid], [windowshid], and [linuxhid],
which will output the data straight from the OS, i.e. integers. Those
objects are for getting data from very esoteric devices, but I would
discourage using them for anything but the situations where [hid] would
not work.
Comparing symbols is fast. [route foo bar baz] is just as fast as
[route 55 242 666]. This is because gensym() ensures that if two
symbols refer to the same text then they necessarily have the same
pointer value. This is a standard: LISP/Smalltalk/Ruby/etc all do it
the same.Actually comparing symbols is much faster than comparing floats, if
you run Pd on a 386 or on a PDA.
That good to know. I was thinking strcmp() versus ==. That makes me
very happy. So comparing symbols in Pd is basically a == operation
using the pointer integers, right? I was thinking I needed to keep
these symbols as short as possible for efficiency's sake. Now I can
happily eliminate the unixy abbrvs:
syn = sync
snd = sound
msc = misc
rep = repeat
pwr = power
These would probably be too long tho:
abs = absolute
rel = relative
btn = button
ff = force_feedback
If you ever feel like checking out my [hid] code, matju, I'd love
advice on optimization. Since it can run up to once every 1ms,
optimization is key.
.hc
Comparing strings would be slower but Pd doesn't have strings.
(I haven't used [hid] yet though.)
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-o------------o-------------o-' | | Mathieu Bouchard (Montréal QC) | | téléphone:+1.514.383.3801---' `-o-- http://artengine.ca/matju -'
If you are not part of the solution, you are part of the problem.
- Eldridge Cleaver