Nuclear powered audio ;)
More seriously, use _Atomic on a few fields that very obviously need it.
That is, channel's buffer pointer (used to signal to the mixer that the
channel is ready for use) and "flow control" flags (stop, done and
pause), and head and tail in the buffer itself. Since QF has been
working without _Atomic (admittedly, thanks to luck and x86's strong
memory model), this should do until proven otherwise. I imagine getting
stream reading out of the RT thread will highlight any issues.
This improves the locality of reference when mixing and removes the
proxy sfx for streamed sounds.
The buffer for streamed sounds is allocated when the stream is opened
(since streamed sounds can't share buffers), and freed when the stream
is closed.
For block sounds, the buffer is reference counted (with the sfx holding
one reference, so currently block buffers never get freed), with their
reference count getting incremented on open and decremented on close.
That the reference counts get to 1 has been confirmed, so all that
should be needed is proper destruction of the sfx instances.
Still need to sort out just why channels leak across level changes.
This is part of a process to shrink channel_t so it doesn't waste locked
memory when it gets moved there. Eventually, only the fields the mixer
needs will be in channel_t itself: those needed for spacialization will
be moved into a separate array.
In the process, I found that channels leak across level changes, but
this appears to be due to the cached sounds being removed during loading
and the mixer never marking them as done (it sees the null sfx pointer
and assumes the channel was never in use). Having the mixer mark the
channel as done seems to fix the leak, but cause a free channel list
overflow. Rather than fight with that, I'll leave the leak for now and
fix it at its root cause: the management of the sound samples
themselves.
The scaling up of the volumes when setting a channel's volume bothered
me. The biggest issue being it hasn't been necessary for over a decade
since the conversion to a float-mixer. Now the volume and attenuation
scaling from protocol bytes is entirely in the client's hands.
This is an extremely extensive patch as it hits every cvar, and every
usage of the cvars. Cvars no longer store the value they control,
instead, they use a cexpr value object to reference the value and
specify the value's type (currently, a null type is used for strings).
Non-string cvars are passed through cexpr, allowing expressions in the
cvars' settings. Also, cvars have returned to an enhanced version of the
original (id quake) registration scheme.
As a minor benefit, relevant code having direct access to the
cvar-controlled variables is probably a slight optimization as it
removed a pointer dereference, and the variables can be located for data
locality.
The static cvar descriptors are made private as an additional safety
layer, though there's nothing stopping external modification via
Cvar_FindVar (which is needed for adding listeners).
While not used yet (partly due to working out the design), cvars can
have a validation function.
Registering a cvar allows a primary listener (and its data) to be
specified: it will always be called first when the cvar is modified. The
combination of proper listeners and direct access to the controlled
variable greatly simplifies the more complex cvar interactions as much
less null checking is required, and there's no need for one cvar's
callback to call another's.
nq-x11 is known to work at least well enough for the demos. More testing
will come.
I had forgotten to test with shared libs and it turns out jack and alsa
were directly accessing symbols in the renderer (and in jack's case,
linking in a duplicate of the renderer).
Fixes#16.
This brings the alsa driver in line with the jack render (progress
towards #16), but breaks most of the other drivers (for now: one step at
a time). The idea is that once the pull model is working for at least
one other target, the jack renderer can become just another target like
it should have been in the first place (but I needed to get the pull
model working first, then forgot about it).
Correct state checking is not done yet, but testsound does produce what
seems to be fairly good sound when it starts up correctly (part of the
state checking (or lack thereof), I imagine).
The sounds are down-mixed to 2 channels (qf does not (yet) support more than
2 channel output), but this allows pretty much anything to be used for a
source of music. Only 5.1 (6 channel), stereo and mono have been tested, but
the others should work (any issues would be mis-interpretation/implementation
of the channel layout).
the resampler is being badly abused for streams, and it's not yet properly
autoconfiscated, but things are working. Better yet, at the correct pitch and
speed.
