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Add support for a binary output mode.

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This commit is contained in:
ehofman 2006-04-29 11:15:44 +00:00
parent ff52ed5072
commit 5594b110e3
1 changed files with 23 additions and 9 deletions
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32
docs-mini/README.protocol
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@ -1,7 +1,6 @@
The generic communication protocol for FlightGear provides a powerfull way
of adding a simple ASCII based output only protocol, just by defining an
XML encoded configuration file and placing it in the $FG_ROOT/data/Protocols
directory.
of adding a simple ASCII based or binary protocol, just by defining an
XML encoded configuration file.
The definition of the protocol consists of variable separators, line separators,
and chuncks of text.
@ -17,8 +16,9 @@ Each chunck defines:
%s string
%i integer (default)
%f float
(not used or needed in binary mode)
<factor> an optionale multiplication factor which can be used for
<factor> an optional multiplication factor which can be used for
unit conversion. (for example, radians to degrees).
<offset> an optional offset which can be used for unit conversion.
(for example, degrees Celsius to degrees Fahrenheit).
@ -45,6 +45,16 @@ any other charachters just need to be added to "Network/generic.cxx"
The var_separator is placed between each variable, while the line_separator is
placed at the end of each lot of variables.
To enable binary mode, simply include a <binary_mode>true</binary_mode> tag in
your XML file. The format of the binary output is tightly packed, with 1 byte
for bool, 4 bytes for int, and 8 bytes for double. At this time, strings are not
supported. A configurable footer at the end of each "line" or packet of binary
output can be added using the <binary_footer> tag. Options include the length
of the packet, a magic number to simplify decoding. Examples:
<binary_footer>magic,0x12345678</binary_footer>
<binary_footer>length</binary_footer>
<binary_footer>none</binary_footer> <!-- default -->
A simple protocol configuration file then could look something like the
following:
@ -52,10 +62,13 @@ following:
<?xml version="1.0"?>
<PropertyList>
<output>
<generic>
<output>
<line_separator>newline</line_separator>
<var_separator>newline</var_separator>
<binary_mode>false</binary_mode>
<chunk>
<name>speed</name>
@ -64,18 +77,19 @@ following:
</chunk>
<chunk>
<name>heading (rad)</name>
<name>heading</name>
<format>H=%02d</format>
<node>/orientation/heading-deg</node>
<factor>57.29578</factor> <!-- degrees to radians -->
<factor>57.29578</factor> <!-- radians to degrees -->
</chunk>
<chunk>
<name>pitch angle (deg)</name>
<name>pitch angle</name>
<format>P=%05.1f</format>
<type>float</type>
<node>/orientation/pitch-deg</node>
</chunk>
</output>
</generic>
</PropertyList>