In addition to now using the framework the playback is triggered by a
timer. For now it is a periodic timer that triggers every 11 ms which
is roughly the current Audio:out period (*).
The driver now also behaves like the other BSD Audio_out driver, i.e,
it always advances the play pointer. That is vital for the Audio_out
stack above the driver to work properly (e.g. the mixer).
(*) It stands to reason if it would be better to use the async ALSA
timer interface instead of using the Timer session.
Fixes#1892.
Instead of only hardcoding "hw" read 'alsa_device' attribute from the
config node to determine the proper playback device. The default value
is still "hw" in case the attribute is not present.
Fixes#1884.
Instead of holding SPEC-variable dependent files and directories inline
within the repository structure, move them into 'spec' subdirectories
at the corresponding levels, e.g.:
repos/base/include/spec
repos/base/mk/spec
repos/base/lib/mk/spec
repos/base/src/core/spec
...
Moreover, this commit removes the 'platform' directories. That term was
used in an overloaded sense. All SPEC-relative 'platform' directories are
now named 'spec'. Other files, like for instance those related to the
kernel/architecture specific startup library, where moved from 'platform'
directories to explicit, more meaningful places like e.g.: 'src/lib/startup'.
Fix#1673