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tricsnex.w

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+\subsection{TRICS NeXus Data Files}
+This section describes the data file handling for the four circle
+diffractometer TRICS at SinQ. TRICS collects a lot of detector frames in
+time intervalls of days or weeks. The data writing scheme has to adress the
+issue, that the HDF routines  cannot ensure that there is no data corruption
+when writing data files. 
+
+Thus the following scheme is implemented: With a special command, the user
+enforces a new file. At that time header information is written. After that
+the file is closed. With another command, the file is reopened and a frame
+is added to it. Each frame data group will hold a flag which decides if the
+frame is valid or not. After writing the frame, the file is closed again.
+This scheme minimises the danger of data corruption.
+
+The current frame number is kept in a non NeXus standard field in the data file
+itself. This allows to reopen files and append data to it. 
+
+The interface to this object looks like this:
+
+@d nxtrics @{
+    typedef struct __NexTrics *pNexTrics;
+
+/*----------------------------- live & death -----------------------------*/
+  pNexTrics CreateNexTrics(pDataNumber pNum, char *pRoot, char *pDict,
+                           SicsInterp *pSics);
+  void      DeleteNexTrics(void *pData);
+
+  int NexTricsFactory(SConnection *pCon, SicsInterp *pSics, void *pData,
+                      int argc, char *argv[]);
+/*----------------------------- interaction ------------------------------*/
+
+  int StartFile(pNexTrics self, SConnection *pCon);
+ 
+  int ReopenFile(pNexTrics self, char *filename);
+
+  int DumpFrame(pNexTrics self, SConnection *pCon);
+
+  int NexTricsAction(SConnection *pCon, SicsInterp *pSics, void *pData,
+                      int argc, char *argv[]);
+ 
+@}
+
+\begin{description}
+\item[CreateNexTrics] creates a new TRICS NeXus data file writing object.
+Parameters are a data number object for the automatic creation of file names
+and the directory name where the data files ought to live. The next
+parameter is the name of the NeXus dictionary file to use for writing.
+\item[DeleteNexTrics] deletes a NexTrics object. The last parameter is the
+name of the SICS interpreter to search for objects. NexTrics will maintain a
+cache of frequently used SICS objects for writing. 
+\item[NexTricsFactory] is the interpreter wrapper function for the command
+to install the nexus data writing object for Trics into the system.
+\item[StartFile] will automatically create a new file and write the header
+information to it.
+\item[DumpFrame] will dump a frame worth of data to the file. Thereby
+reopening and closing it. This will be called for each detector shot, i.e.
+in the end three frames will be written when all three detectors have been
+installed at TRICS.
+\item[NexTricsAction] is the command interface to the TRICS NeXus data file
+writing object.
+\end{description}
+
+@o nextrics.h @{
+/*----------------------------------------------------------------------------
+                           N E X T R I C S
+ 
+  An object for writing NeXus data files for the four ciclre diffractometer
+  TRICS at PSI. Can be used as basis for writing files for other four
+  circles equiped with a PSD as well.
+
+  copyright: see copyright.h
+
+  Mark Koennecke, April 1998
+------------------------------------------------------------------------------*/
+#ifndef NEXTRICS
+#define NEXTRICS
+@<nxtrics@>
+#endif
+@}