P8.9 CFITSIO, v2.0: A New Full-Featured Data File API

William D. Pence (NASA/GSFC HEASARC)

Reference URL: http://heasarc.gsfc.nasa.gov/fitsio

CFITSIO has evolved over 7 years into a very rich and powerful data file API which combines many of the best features of other data interfaces. Version 2.0 of CFITSIO has just been released and is the result of a large collaborative effort by many groups and individuals. It offers a high level of data abstraction by hiding most of the data structural details from the application program and provides an `object oriented' view of the data. It is also extremely fast, producing typical data throughput rates of 5 - 10 MB/s on magnetic disk and of order 100 MB/s when the data file is stored in shared or core memory. Some of the new features in CFITSIO are:

• Supports direct network assess to http:// or ftp:// FITS files.
• Supports I/O to FITS files in memory or shared memory for better performance.
• Tables may be filtered or modified at run time by adding qualifiers to the file name using a general syntax that supports arbitrarily complex expressions.
• Tables may be filtered at run time using Good-Time-Interval files (GTIs) and SAOimage region files. The application only sees the table rows that satisfy the filtering expression.
• Any 2 table columns may be binned into a 2-dimensional FITS image at run time. The application program then just sees and opens the FITS image, not the original table.
• A single FITS file may be opened multiple times by an application, which can then read or write to different extensions in the FITS file simultaneously.
• FITS files may be piped between tasks using the stdin and stdout streams.
• CFITSIO is now Y2000 compliant and supports the new FITS date+time format.
• New routines for dealing with large sets of hierarchically organized data files have been added.
• A fully functional Fortran-callable API is available.
• CFITSIO now uses `plug-in' drivers for reading or writing files on each different `device'. In the future, new drivers will be provided for tape devices, to support new data compression algorithms, and even to read other data formats besides FITS (e.g., IRAF-format images and tables).