PSI sics-cvs-psi_pre-ansto

doc/programmer/fowrite.tex

@@ -0,0 +1,22 @@
+\subsection{FOCUS Data File Writing}
+FOCUS writes NeXus files. This file writing is impleneted in the files
+fowrite.h and fowrite.c. So these files contain the code for writing
+FOCUS NeXus files. But there is more to it: FOCUS has a scheme where
+the data file is updated any 20 minutes during the course of an
+measurement. This scheme is implemented with the following bits and
+pieces:
+\begin{itemize}
+\item Data file updating is triggered by a special task function,
+FoTask, which is installed into the SICS tasker when counting starts. 
+\item The module registers callbacks with the histogram memory which
+ are invoked when counting starts or ends. These callback functions
+ take care of craeting a new file and updating it. 
+\item There is a special command which allows to start and update the
+ data file manually.  
+\end{itemize}
+ 
+As is it not likely that more then one FOCUS writing object is ever
+needed, all the data structures are file statics in fowrite.c. The
+external interface of this module is just a interpreter initialisation
+function and a interpreter interface function for interacting with the
+data file writing object.