axfer: add an option to dump available hardware parameters
In ALSA PCM interface, before configuring hardware actually, applications
can request available set of hardware parameters for runtime of PCM
substream. The set of parameters are represented and delivered by a
structure.
In alsa-lib PCM API, the above design is abstracted by a series of
snd_pcm_hw_params_xxx() functions. An actual layout of the structure is
hidden from applications by an opaque pointer.
In aplay, '--dump-hw-params' option is for this purpose. With this option,
the command output available set of the hardware parameters.
This commit adds support for the option. Unlike aplay, this commit takes
this program to finish after dumping the parameters for simplicity of
usage.
I note that all of combinations in the set are not necessarily available
when the PCM substream includes dependencies of parameters described by
constraints and rules.
git://git.alsa-project.org / alsa-utils.git / commit