Extend the ControlValue class with a reserve() function to set the value
without actually copying data, and a non-const data() function that
allows writing data directly to the ControlValue storage. This allows
allocating memory directly in ControlValue, potentially removing a data
copy.
Note that this change was implemented before ByteStreamBuffer gained the
zero-copy read() variant, and doesn't actually save a copy in the
control serializer. It however still simplifies
ControlSerializer::loadControlValue().
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
8daf20485b