2 USER's GUIDE

2.1 THE VARIOUS TYPES OF FILES

The data on which the slx is operating are:

· Setup files and single setup parameters.

· Instrument Specific Dictionaries.

· Alias Conversion Tables.

· Data file FITS header information.

The various types are shortly described in the following.

2.1.1 Environment Variables

SLX uses the following INS environment variables

· INS_ROOT. Defines the root directory of the INS directory structure.

· INS_SETUPPATH. Colon separated list of paths where Setup-Files can be located.

· INS_USER. Defines the INS user in the INS Directory Tree.

· INS_USER_PATH. Colon separated list of paths where the user's `private' files can be located. This should refer to directories in the $INS_ROOT/$INS_USER/MISC directory.

A subroutine slxLocateSetUpFile() is provided to search for set-up files and set-up related files. Furthermore a utility, slxFindSetUp, is provided which can be called from a shell to perform the location of a set-up file.

Note, that in case of files with redundant names, the first occurrence located will be used.

2.2 SLX DYNAMIC BUFFER

Operations on setup parameters can be done either directly on files or using a static buffer in memory which is handled locally by the various set-up manipulation functions. A variable of the type slxDYN_BUF must be declared. Before starting to use it, the function slxInitDynBuf() should be called using the variable as input. Afterwards various operations can be carried out on the buffer, such as loading of a setup (slxLoadSetup()), merging setup files (slxMergeSetupBuf()), and retrieval/search of keywords (slxGetKeywordBuf(), slxGetNextLineBuf()). Storing a line in a buffer is done using slxStoreLineBuf().

Note that when storing a line in a buffer, this corresponds to merging with the present contents in the buffer. In may be desirable to reset the buffer from time to time, e.g. after a setup operation has been performed and a new one is carried out; this is done using the function slxResetDynBuf().

When a Dynamic Buffer is not used any longer, the memory occupied should be freed, by calling slxResetDynBuf().

Using Dynamic Buffers, increases the performance quite a lot, and it is therefore recommendable to use it whenever possible. It is possible to have as many Dynamic Buffers as desirable.

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