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Nothing uses libs/sig yet, but this will probably become an issue
once that changes.
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This is a first approximation of separating the core modules and
threaded rendering from the cli-centric rototiller program and
its sdl+drm video backends.
Unfortunately this seemed to require switching over to libtool
archives (.la) to permit consolidating the per-lib and
per-module .a files into the librototiller.a and linking just
with librototiller.a to depend on the aggregate of
libs+modules+librototiller-glue in a simple fashion.
If an alternative to .la comes up I will switch over to it,
using libtool really slows down the build process.
Those are implementation/build system details though. What's
important in these changes is establishing something resembling a
librototiller API boundary, enabling creating alternative
frontends which vendor this tree as a submodule and link just to
librototiller.{la,a} for all the modules+threaded rendering of
them, while providing their own fb_ops_t for outputting into, and
their own settings applicators for driving the modules setup.
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Added a triangle wave
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This builds minimally upon the existing sine wave code,
just use the sign to drive the signal high or low.
Wikipedia shows a third state for 0 values, but that's for a -1..+1
signal. I'm producing all 0-1 signals as it's more convenient for
this application, but it seems like it would be awkward to return
.5f for the 0 case. So 0 is being treated as just another positive
value; high.
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Provides improved ergonomics when using the bulitin ops, and much
appreciated arity and type checking.
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Added some rudimentary refcounting so sig_t's can be readily shared
by multiple sig_t's.
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Seems broken, fix it correctly later.
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off by one order of magnitude
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map 0-1 inputs to their inverse 1-0
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Rename inv->neg, preparation for a new sig_ops_inv for inverting
0..1 to 1..0
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Included a little hack to defend against divide by zero, seems
reasonable given the intended use cases.
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This is a specialized version of sig_ops_scale which assumes a
min..max range of -1..+1
nvidia register combiners docs describe this operation as "expand
normal", and they have several variants, but I don't want to go
too crazy here right now. Plain expand it is.
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This assumes the input value is always 0-1, but may be used to produce
values in any signed range, mapped linearly to the input.
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aka negation
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The whole idea was to produce values 0-1, except of course
sig_ops_{mult,const} where one could deliberately get out of
these bounds.
Everything else should stay within 0-1 as it makes everything
much more composable.
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Supply two sig_t *'s: a, b
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Supply three sig_t *'s: value, min, max
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Added a simple test exercising pow and round
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The flexible array of void *'s would just align to a pointer,
which may not be safe for all members of whatever gets shoved in
here.
In an effort to make it more robust, make it an array of a junk
drawer union of types.
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Comment was vestigial from ops_mult.c which ops_lerp.c was derived
from.
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(Ab)uses rand_r by feeding ticks_ms as seedp for pseudo-random
numbers deterministically derived from ticks_ms.
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Make sig_ops_t.destroy functions consistently after init, no
functional changes.
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This takes three signals; a, b, and t
t controls the weight interpolating between a and b, they all key
off the same time ticks_ms.
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Now hz can vary with time as well...
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The simplest of signals: a constant value.
The immediate need for this is to convert ops_sin_ctxt_t.hz to
another sig_t enabling varying hz with time, while still being
able to have a fixed hz as well.
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This adds a small framework of sorts for creating and composing signal
generators.
Two generators are implemented at this time; sig_ops_sin and sig_ops_mult
sig_ops_sin accepts a hz variable and will produce a sine wave of that
frequency.
sig_ops_mult accepts two sig_t generators and multiplies their outputs
Callers may construct their own sig_ops_t ops structs and supply them to
sig_new(), but it's expected that libs/sig will grow a collection of
commonly used generators which can then be used by simply passing their
sig_ops_$foo to sig_new().
See the test code at the bottom of libs/sig/sig.c for some contrived
sample usage. Note by composing multiple sig_ops_sin generators with
a sig_ops_mult generator, one can already easily construct a synth-like
LFO generator.
Some obvious todos are to add triangle/sawtooth/square wave generators.
More compositional generators may be interesting as well, like additive
and subtractive for example. Those will need to implement clipping, as
it's expected that the generators *always* stay within unity (0-1).
No modules use this yet, but I expect to wire this up to rtv for driving
knobs.
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