Merge branch 'cpp_prefs'

1 files changed, 73 insertions, 0 deletions

diff --git a/docs/doxygen/other/main_page.dox b/docs/doxygen/other/main_page.dox
index abdc21b0c..e7d4685f7 100644
--- a/docs/doxygen/other/main_page.dox
+++ b/docs/doxygen/other/main_page.dox
@@ -329,4 +329,77 @@ they can also serve as examples. See the gr_complex_to_xxx.h file for
 examples of various blocks that make use of Volk.
 
 
+\section prefs Configuration / Preference Files
+
+GNU Radio defines some of its basic behavior through a set of
+configuration files located in
+${prefix}/etc/gnuradio/conf.d. Different components have different
+files listed in here for the various properties. These will be read
+once when starting a GNU Radio application, so updates during runtime
+will not affect them.
+
+The configuration files use the following format:
+
+\code
+# Stuff from section 1
+[section1]
+var1 = value1 
+var2 = value2 # value of 2
+
+# Stuff from section 2
+[section2]
+var3 = value3
+\endcode
+
+In this file, the hash mark ('#') indicates a comment and blank lines
+are ignored. Section labels are defined inside square brackets as a
+group distinguisher. All options must be associated with a section
+name. The options are listed one per line with the option name is
+given followed by an equals ('=') sign and then the value. All section
+and option names must not have white spaces (actually, all white
+spaces are ignored).
+
+The value of an option can be a string or number and retrieved through
+a few different interfaces. There is a single preference object
+created when GNU Radio is launched. In Python, you can get this by
+making a new variable:
+
+\code
+p = gr.prefs()
+\endcode
+
+Similarly, in C++, we get a reference to the object by explicitly
+calling for the singleton of the object:
+
+\code
+  gr_prefs *p = gr_prefs::singleton();
+\endcode
+
+The methods associated with this preferences object are (from class gr_prefs):
+
+\code
+  bool has_section(string section)
+  bool has_option(string section, string option)
+  string get_string(string section, string option, string default_val)
+  bool get_bool(string section, string option, bool default_val)
+  long get_long(string section, string option, long default_val)
+  double get_double(string section, string option, double default_val)
+\endcode
+
+When setting a Boolean value, we can use 0, 1, "True", "true",
+"False", "false", "On", "on", "Off", and "off".
+
+All configuration preferences in these files can also be overloaded by
+an environmental variable. The environmental variable is named based
+on the section and option name from the configuration file as:
+
+\code
+  GR_CONF_<SECTION>_<OPTION> = <value>
+\endcode
+
+The "GR_CONF_" is a prefix to identify this as a GNU Radio
+configuration variable and the section and option names are in
+uppercase. The value is the same format that would be used in the
+config file itself.
+
 */