FXGREAD Name
FXGREAD
Author
Craig B. Markwardt, NASA/GSFC Code 662, Greenbelt, MD 20770
craigm@lheamail.gsfc.nasa.gov
UPDATED VERSIONs can be found on my WEB PAGE:
http://cow.physics.wisc.edu/~craigm/idl/idl.html
Purpose
Perform an unformatted read on a generic resource.
Major Topics
File I/O, Pipes, URLs, FITS Calling Sequence
FXGREAD, UNIT, BUFFER, TRANSFER_COUNT=TC
Description
FXGREAD performs an unformatted read on the unit UNIT. The UNIT
must have previously been opened by FXGOPEN.
Currently only unformatted reads are permitted because the precise
number of bytes to read must be known ahead of time.
In other respects, this procedure is similar to the READU built-in
IDL procedure.
You must use the specialized 'FXG' style functions to read, write
and seek on file units opened with FXGOPEN:
FXGOPEN - open resource
FXGCLOSE - close resource
FXGREAD - read from resource
FXGWRITE - write to resource
FXGSEEK - seek on resource (i.e., perform POINT_LUN)
FXGFILTERED - determine if resource is a normal file.
Inputs
UNIT - the unit number to operate on. The unit must have been
previously opened by FXGOPEN.
BUFFER - an array of the desired type and size is passed upon
input to FXGREAD. Only basic types are permitted. Upon
output, the array will have been filled with data from
the resource. The full extent of the transfer can be
determined by examining the TRANSFER_COUNT.
Keyword Parameters
TRANSFER_COUNT - upon output, contains the number of elements
transferred to BUFFER.
Modification History
Written, 1999, CM
Documented, 02 Oct 1999, CM
Changed copyright notice, 21 Sep 2000, CM