sbus: Add sbus_vtable and update codegen to support it

Each interface is a vtable structure derived from
sbus_vtable, in the sense that it has an sbus_vtable
struct as its first argument. This lets us upcast the
interface vtable structure to an sbus_vtable and dispatch
to it dynamically and cleanly.

The interface metadata contains information about which
vtable offset in the interface metadata should be dispatched
to for a given function. This is a common scheme, not only
among dbus implementations, but also compiled languages.

Currently all the vtable functions are of type
sbus_msg_handler_fn. These are the handlers we are familiar
with and perform raw processing of the message. Later commits
will introduce type safe handlers that levelage compile checking
and automatic argument packing/unpacking.

Although this may seem contrived now, the remainder of the
dbus infrastructure work will build on this, including
ofd.Properties, ofd.ObjectManager, ofd.Introspect, compiler
checked type safe unpacking/packing, etc.

The codegen now generates vtable structures for each interface
along-side the metadata, and fills in vtable offsets
appropriately.

It is obviously still possible to hand-craft such vtables and
metadata if needed for a special case.

Once again examples output can be found at:

  src/tests/sbus_codegen_tests_generated.h

Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
Reviewed-by: Sumit Bose <sbose@redhat.com>
Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/Makefile.am b/Makefile.am
index d7e624367..18f7a40af 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -680,7 +680,7 @@ SUFFIXES = .xml _generated.h _generated.c
 .xml_generated.h:
 	$(srcdir)/$(SBUS_CODEGEN) --mode=header --output=$@ $<
 .xml_generated.c:
-	$(srcdir)/$(SBUS_CODEGEN) --mode=source --output=$@ $<
+	$(srcdir)/$(SBUS_CODEGEN) --mode=source --include=$(@:.c=.h) --output=$@ $<
 
 # Regenerate when codegen changes
 CODEGEN_CODE = \