Initial revision

danu.w

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+\subsection{Data Number}
+In some points of its life SICS has to write data files. The file names 
+usually consist of a header, a serial number and an indicator for the 
+year. The serial number must be unique and steadliy increasing. In order to
+achieve this, the serial number are written into a file after any change.
+Incrementing the serial number thus involves the following steps:
+\begin{itemize}
+\item Open file and read current number.
+\item Increment number
+\item Write File and close
+\end{itemize}
+This little task is implemented in this module.
+
+The interface to this looks like:
+@d dni @{
+    typedef struct __DataNumber *pDataNumber;
+
+    pDataNumber CreateDataNumber(char *pFilename);
+    void        DeleteDataNumber(void *pData);
+
+    int IncrementDataNumber(pDataNumber self, int *iYear);
+
+    int DecrementDataNumber(pDataNumber self);
+
+    int DNWrapper(SConnection *pCon, SicsInterp *pSics, void *pData,
+                  int argc, char *argv[]);
+
+    int DEWrapper(SConnection *pCon, SicsInterp *pSics, void *pData,
+                  int argc, char *argv[]);
+
+    int DNFactory(SConnection *pCon, SicsInterp *pSics, void *pData,
+                  int argc, char *argv[]);
+@}
+\begin{description}
+\item [CreateDataNumber] creates a data number data structure. It checks if
+the file requested as parameter exists and asserts if not. Returns a pointer
+on success, NULL else.
+\item [DeleteDataNumber] deletes a data number structure form memory. 
+\item [IncrementDataNumber] is the main working function of this module.
+It performs the steps listed above. It returns a new id for the data number
+in case of success, a negative value otherwise. iYear is filled with a value
+for the year. 
+\item[DecrementDataNumber] decrements the data number and is used for 
+ implementing the killdata function. Whis is the invalidation of a 
+ data file by overwriting it.
+\item[DNWrapper] is the wrapper function which makes DataNumber accessible
+from within SICS. 
+\item[DEWrapper] is the wrapper for the killdata functionality.
+\item [DNFactory] is the SICS factory function which creates a Data Number
+object from the initialisation file. Only parameter is the filename.
+\end{description}
+
+@o danu.h -d @{
+/*-----------------------------------------------------------------------
+                        D A T A N U M B E R
+
+  A module to provide a unique data number for data file writing.
+
+  Mark Koennecke, Juli 1997
+  
+  copyright: see implementation file.
+
+---------------------------------------------------------------------------*/
+#ifndef SICSDATANUMBER
+#define SICSDATANUMBER
+
+@<dni@>
+
+#endif
+@}
+
+
+
+
+
+
+