The Mutex on the RTL data reader thread does not "force" the data
processing thread to execute. Therefore, if the processor is busy, it is
possible for a second RTL callback to occur before the data from the
first has been processed. This will cause the loss of the first data,
but worse, it will cause a slip in the timestamp. This upsets Beamfinder
and MLAT operation in PlanePlotter.
To solve this, keep a Fifo buffer which is filled by the callback
thread, and emptied by the data processing thread. The fifo is the same
size as the number of buffers requested in the call to
rtlsdr_read_async().
Note - we only put the value of the pointer supplied in the callback
into the fifo. We do not attempt to cache the data in the buffer pointed
to by the pointer. This would require us to memcopy() 2Mbytes per
second, which we don't want to do if we don't have to because it will
only make the processor loading worse. Instead, we assume that the data
in the buffer will remain valid after the callback returns, at least
until it is overwritten by new data.
It is still possible for us to lose data if we can't process it quickly
enough. However, we can now detect this loss of data when the fifo is
almost full, and correct the timestamp for the lost block/blocks.
Create separate makefiles for dump1090, view1090 and ppup1090. These can
be run with the command line "make -f makedump1090", "make -f
makeview1019" and "make -f makeppup1090"
Pass dump1090 version number into ppup1090 uploader so that coaa1090.obj
doesn't need re-compiling between versions.
Remove ppup1090 from general Makefile - it's not intended for anything
other than RPi, so gives linker errors on other (non Linux raspian)
systems.
Updated the way socket handles are used in View1090 to maintain
compatibility between UNIX and Windows.
Added the initial attempt at a Planeplotter uploader
No changes to dump1090, (except the version number)
Include a sample Linux batch start file called dump1090.sh for use when
running dump1090 headless. This file needs to be copied to the
/etc/init.d/ subdirectory on your raspberry pi, and marked as
executable. Then when you re-start your RPi, dump1090 will start-up
auto-magically and run as a sort of server to allow both local and
remote connection to it's various internet ports.
Modified the Makefile to build a new headless helper application called
view1090
Added view1090. This is an executable that allows you to connect to
dump1090 when it is running and 'see' the interactive screen display.
The default is to try and connect to dump1090 on IP address 127.0.0.1
port 30005. This should work if you are running on the same RPi as
dump1090 and using the default dump1090 port settings. However, if
you're running on a different machine you will have to specify the IP
address of the RPi running dump1090 using the --net-bo-ipaddr switch.
Something like "view1090 --net-bo-ipaddr 192.168.2.65" . You may also
have to sudo it, depending on your privilige settings.
I've also compiled view1090 as a Wiin32 exe, so you should be able to
run it under any 32 bit version of Microsoft Windows - i.e. Win95, Win
2K, Win XP, Win 7 etc. It may work on Win 8 and 64 bit Windows, but I
haven't tried it. The Win32 version is compiled from the same source, so
takes all the same command line switches.
The modesReadFromClient() funtion is called from modesReadFromClients(),
which in turn is called from backgroundTasks(). backgroundTasks() is
called from within the main processing loop.
However, modesReadFromClient() can and does block. It attempts to read
characters from the input stream, and loops whilst there was no error.
This stalls the main RTL processing loop until an error occurs. In order
to support simultaneous local reception (via our RTL dongle) and remote
forwarding (data received from the interweb) we cannot allow this
internet read to stall.
To fix this, in modesReadFromClient() attempt to read a buffer of data
(currently 0x400 bytes). If we get a full buffer of bytes, then process
them, and attempt to read another full buffer. Keep doing thios untill
we read only a partial buffer (less than 0x400 bytes). Process the
partial buffer bytes and return.
This allows us to occasionally process data that is arriving from the
internet (which is buffered anyway in the TCP stack), without blocking
local RTL dongle decoding.
Ok - this is likely to upset some people. Up until now, the vast
majority of the code has been in just one file - dump1090.c. This file
has grown so that it was approaching of 5000 lines long, and it was
becoming unmanagable. So I've split the file into several modules,
hopefully along fairly logical boundaries. The files are :
1) dump1090.c : Basically just the main() entry function, the help
function, the RTL dongle hardware interface, and a few orphan functions
that don't really fit anywhere else.
2) mode_s.c : This contains all the mode S / ADSB decoding functions.
3) mode_ac.c : This contains all the mode A & C decoding functions
4) interactive.c : This contains all the functions to maintain an
internal list of aircraft seen over the last period, and functions to
print them out to the local console.
5) net_io.c : This contains all the network input/output functions
allowing data to be passed in/out to/from other receivers, in formats
such as SBS-1/3, Beast, AVR and JavaScript.
Hopefully this should provide an easier way forward if/when more
functions are added.
Create two different Time-To-Live parameters for the interactive display
list.
1) Modes.interactive_display_ttl defines for how long the display of an
aircraft persists after the last received message. The default is
MODES_INTERACTIVE_DISPLAY_TTL, which is set to 60 seconds. This replaces
the previous Modes.interactive_ttl/MODES_INTERACTIVE_TTL settings (which
were also 60 seconds)
2) Add an additional Modes.interactive_delete_ttl parameter, and
default it to MODES_INTERACTIVE_DELETE_TTL, shich is set to 300
seconds/5 minutes. This defines for how long an aircraft persists in the
list structure after the last received message before being deleted.
Also tidy up a few comments.
This is the start of breaking the main dump109.c file into smaller
modules to make it a bit more maintainable.
Move all the #define and structure declarations into dump1090.h
