<systemlib/err.h> --> "systemlib/err.h" that fix_headers.sh
would miss because it comes after code it doesn't understand.

Effectively remove the '__EXPORT extern perf_counter_t perf_alloc('
line, because currently perf_alloc is defined to be NULL, and
after running fix_headers.sh that happens *before* this header
is included (the order of headers will be changed).

Do not define NULL to be (void*)0: that only works for C.
In fact, the conversions needed for NULL are so full of exceptions
that standard C++ introduced a new *keyword*: nullptr.
That's what we really should be using for C++ code.
In this case I just include the correct header to define NULL
the correct way.

Not really related to the header line:
Removed an #include <time.h> because I noted that px4_time.h
was already included... and moved a #include <sys/time.h>
to the top of the file (not really a fan of including headers
in the middle unless absolutely necessary).
Removed a include of queue.h because I noted it wasn't used.

Added missing functions that were added for other targets but not for qurt.

Added workaround for missing sem_timedwait(). This may have a performance
impact until a sem_timedwait is supported.

std::to_string is not supported by the hexagon compiler

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Updated DSPAL version.
Fixed missing lib in config.
Fixed heafers for missing timespec definition.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Workaround required Eigen downgrade to 3.2. Hexagon toolchain does
not support C++11 features of newest version of Eigen.

Running make qurt_fixup will downgrade and patch Eigen for qurt.
Running make restore will revert the patch and do a git submodule update
to restore the expected Eigen version.

Added a "restore" target to undo qurt_fixup

Before doing a qurt build run:

    make qurt_fixup

That will downgrade Eigen to 3.2 and apply the require patch.
To build another target after downgrading:

    make restore

Them make the desired target (other than qurt).

Fixed type used in orb_priority to be consistent with the code
(int* was used in declaration but int32_t* used in code)

Removed unused class member variable in sensors.cpp

Added cmake fix for unit tests. The location of px4_log.c changed.

Fixed the qurt drv_hrt.c implementation to use us instead of ms for time resolution

Added px4_led.c to nuttx platform layer
Use the posix version of px4_led.c for nuttx so we don't end up with
duplicate files. It was moved out of common because it is not used by qurt.

Changed PX4_DEBUG to PX4_WARN when checking for the error condition for store_poll_waiter in vdev.cpp

Updated the px4_log.h file to make calls to the qurt_log functions.
The qurt_log function is defined in the platforms/qurt layer.

Added an option to control starting the commander module in HIL mode.

Moved the flight specific drivers to the configuration file instead of adding them
to the common tool chain file because HIL mode does not need them.

Added the uorb Subscriber and Publisher classes

Call PX4_ISFINITE macro instead of isfinite().

Added px4_led.c to nuttx platform layer
Use the posix version of px4_led.c for nuttx so we don't end up with duplicate files.
It was moved out of common because it is not used by qurt.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Changes to support QuRT intrgration with DSPAL and
move from simulator to real HW.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

The posix layer implementations should work on QuRT.

QuRT needs to provide a way for getting the current time.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

A stub for hrt_sleep was removed. Will add back when DSPAL supports
sleep.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

DSPAL for QuRT is still missing the pthreads exports and there is no
exported sleep function. These functions are stubbed out for the time being.

This is based on the 6.4.05 version of the Hexagon tools.

The Hexagon tools and DSPAL are needed to build the qurt target.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Also fixed naming of mavlink files for NuttX build.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Added more queue support to linux/px4_layer.

Use virt char devices for ms5611, and mavlink.

Added more HRT functionality. uORB latency test
now fails. Likely due to bad HRT impl for Linux.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

The High Resilution Timer functions are stubbed out for now.

Certain queue functions are required to compile uORB so adding
the queue.c from NuttX.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

hrt_call_init() can be used to initialise (zero) a hrt_call structure
to ensure safe usage. The hrt_call_every() interface calls this
automatically.

hrt_call_delay() can be used to delay a current callout by the given
number of microseconds

hrt_call_init() can be used to initialise (zero) a hrt_call structure
to ensure safe usage. The hrt_call_every() interface calls this
automatically.

hrt_call_delay() can be used to delay a current callout by the given
number of microseconds

Add an interrupt-safe way of storing the current time into a timestamp.