Due to the way the headers are organized changing a single change in an
inertial sensor driver would trigger a rebuild for most of the files in
the project. Time could be saved by using ccache (since most of the
things didn't change) but we can do better, i.e. re-organize the headers
so we don't have to re-build everything.
With this patch only AP_InertialSensor/AP_InertialSensor.h is exposed to
most users. There are some corner cases to integrate with some example
code, but most of the places now depend only on this header and this
header doesn't depend on the specific backends.
Now changing a single header, e.g. AP_InertialSensor_L3G4200D.h triggers
a rebuild only of these files:
$ waf copter
'copter' finished successfully (0.000s)
Waf: Entering directory `/home/lucas/p/dronecode/ardupilot/build/minlure'
[ 80/370] Compiling libraries/AP_InertialSensor/AP_InertialSensor.cpp
[ 84/370] Compiling libraries/AP_InertialSensor/AP_InertialSensor_L3G4200D.cpp
[310/370] Linking build/minlure/ArduCopter/libArduCopter_libs.a
[370/370] Linking build/minlure/bin/arducopter
Waf: Leaving directory `/home/lucas/p/dronecode/ardupilot/build/minlure'
Lucas De Marchi
Andrew Tridgell