topology: Add option to pass pre-processor definitions

[GitHub pull_request - opened <github@xxxxxxxxxxxxxxxx>]

alsa-project/alsa-utils pull request #117 was opened from ranj063:

Add a -D switch to be able to pass pre-processor definitions that will
be used to expand arguments in the input config file. This will be
useful to generate multiple topology binaries from the same input config
file with different argument values.

For example: if we had a pipeline config as follows:

Object.Pipeline {
	volume-playback.1 {
		dynamic_pipeline $DYNAMIC_PIPELINE
	}
}

We can define an argument for DYNAMIC_PIPELINE as:

@args [ DYNAMIC_PIPELINE ]
@args.DYNAMIC_PIPELINE {
	type integer
	default 0
}

And when pre-processin the conf file pass "-D DYNAMIC_PIPELINE=1" to enable
dynamic pipeline in the topology.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan@xxxxxxxxxxxxxxx>

Request URL   : https://github.com/alsa-project/alsa-utils/pull/117
Patch URL     : https://github.com/alsa-project/alsa-utils/pull/117.patch
Repository URL: https://github.com/alsa-project/alsa-utils