void dlabbs_c ( SpiceInt handle,
SpiceDLADescr * descr,
SpiceBoolean * found )
Begin a backward segment search in a DLA file.
Variable I/O Description
-------- --- --------------------------------------------------
handle I Handle of open DLA file.
descr O Descriptor of last segment in DLA file.
found O Flag indicating whether a segment was found.
handle is the integer handle associated with the file to be
searched. This handle is used to identify the file in
subsequent calls to other DLA or DAS routines.
descr is the descriptor of the last DLA segment in the
file associated with `handle'.
`descr' is valid only if the output argument `found' is
found is a logical flag indicating whether a segment was
found. `found' has the value SPICETRUE if the file
contains at least one segment; otherwise `found' is
1) If the input file handle is invalid, the error will be
diagnosed by routines in the call tree of this routine.
2) If an error occurs while reading the DLA file, the error
will be diagnosed by routines in the call tree of this
3) If the input descriptor is invalid, this routine will
fail in an unpredictable manner.
See description of input argument `handle'.
DLA files are built using the DAS low-level format; DLA files are
a specialized type of DAS file in which data are organized as a
doubly linked list of segments. Each segment's data belong to
contiguous components of character, double precision, and integer
This routine supports backward traversal of a DLA file's segment
list. Note that it is not necessary to call this routine to
conduct a backward traversal; all that is necessary is to have
access to the last descriptor in the file, which this routine
1) Open a DLA file for read access, traverse the segment
list from back to front, and display segment address
and size attributes.
#define FILSIZ 256
SpiceChar fname [ FILSIZ ];
Prompt for the name of the file to search.
prompt_c ( "Name of DLA file > ", FILSIZ, fname );
Open the DLA file for read access. Since DLA
files use the DAS architecture, we can use DAS
routines to open and close the file.
dasopr_c ( fname, &handle );
Begin a backward search. Let `descr' contain
the descriptor of the last segment.
segno = 0;
dlabbs_c ( handle, &descr, &found );
while ( found )
Display the contents of the current segment
printf ( "\n"
"Segment number (offset from end of file) = %d\n"
" Backward segment pointer = %d\n"
" Forward segment pointer = %d\n"
" Integer component base address = %d\n"
" Integer component size = %d\n"
" D.p. component base address = %d\n"
" D.p. component size = %d\n"
" Character component base address = %d\n"
" Character component size = %d\n"
Find the previous segment.
current = descr;
dlafps_c ( handle, ¤t, &descr, &found );
Close the file using the DAS close routine.
dascls_c ( handle );
return ( 0 );
N.J. Bachman (JPL)
-CSPICE Version 1.0.0, 10-JAN-2017 (NJB)
begin backward search in dla file