Index Page dlafns_c

A B C D E F G H I J K L M N O P Q R S T U V W X

Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries

#### Procedure

       void dlafns_c ( SpiceInt               handle,
                       ConstSpiceDLADescr   * descr,
                       SpiceDLADescr        * nxtdsc,
                       SpiceBoolean         * found    )

#### Abstract

       Find the segment following a specified segment in a DLA file.

#### Required_Reading

       DAS
       DLA

#### Keywords

       DAS
       DLA
       FILES
       SEARCH

#### Brief_I/O

       Variable  I/O  Description
       --------  ---  --------------------------------------------------
       handle     I   Handle of open DLA file.
       descr      I   Descriptor of a DLA segment.
       nxtdsc     O   Descriptor of next segment in DLA file.
       found      O   Flag indicating whether a segment was found.

#### Detailed_Input

       handle      is the DAS 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 a DLA segment in the file
                   associated with `handle'.

#### Detailed_Output

       nxtdsc      is the descriptor of the next DLA segment following the
                   segment associated with the input argument `descr'.

                   `nxtdsc' is valid only if the output argument `found' is
                   SPICETRUE.

       found       is a logical flag indicating whether the next segment was
                   found.  `found' has the value SPICETRUE if the segment was
                   found; otherwise `found' is SPICEFALSE.

#### Parameters

       None.

#### Exceptions

       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
          routine.

       3) If the input descriptor is invalid, this routine will
          fail in an unpredictable manner.

#### Files

       See description of input argument `handle'.

#### Particulars

       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
       type.

       This routine supports forward traversal of a DLA file's segment
       list.  A forward traversal may be started from any segment in
       the file; it is not necessary to call dlabfs_c first.  The role
       of dlabfs_c is simply to return the descriptor of the first
       segment in the file.

#### Examples

       1)  Open a DLA file for read access, traverse the segment
           list from front to back, and display segment address
           and size attributes.

              #include "SpiceUsr.h"
              #include "SpiceDLA.h"
              #include <stdio.h>

              int main()
              {
                 /.
                 Local parameters
                 ./
                 #define FILSIZ           256

                 /.
                 Local variables
                 ./
                 SpiceBoolean            found;
                 SpiceChar               fname  [ FILSIZ ];
                 SpiceDLADescr           current;
                 SpiceDLADescr           descr;
                 SpiceInt                handle;
                 SpiceInt                segno;

                 /.
                 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 forward search.  Let `descr' contain
                 the descriptor of the first segment.
                 ./
                 segno = 0;

                 dlabfs_c ( handle, &descr, &found );

                 while ( found )
                 {
                    /.
                    Display the contents of the current segment
                    descriptor.
                    ./

                    ++segno;

                    printf ( "\n"
                             "\n"
                             "Segment number = %d\n"
                             "\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",
                             (int)(segno),
                             (int)(descr.bwdptr),
                             (int)(descr.fwdptr),
                             (int)(descr.ibase),
                             (int)(descr.isize),
                             (int)(descr.dbase),
                             (int)(descr.dsize),
                             (int)(descr.cbase),
                             (int)(descr.csize)                                  );

                    /.
                    Find the next segment.
                    ./
                    current = descr;

                    dlafns_c ( handle, &current, &descr, &found );
                 }

                 /.
                 Close the file using the DAS close routine.
                 ./
                 dascls_c ( handle );

                 return ( 0 );
              }

       The program outputs:

          Name of DLA file > /kernels/gen/dsk/phobos_3_3.bds

          Segment number = 1

             Backward segment pointer         = -1
             Forward segment pointer          = -1
             Integer component base address   = 11
             Integer component size           = 3311271
             D.p. component base address      = 0
             D.p. component size              = 494554
             Character component base address = 0
             Character component size         = 0

#### Restrictions

       None.

#### Literature_References

       None.

#### Author_and_Institution

       N.J. Bachman    (JPL)

#### Version

       -CSPICE Version 1.0.0, 09-JAN-2017 (NJB)(EDW)

          Removed unnecessary include statements.
          Updated header example.

       DSKLIB Version 1.0.1, 23-JAN-2013 (NJB)

          Added third exception description to the Exceptions
          header section.

       DSKLIB Version 1.0.0, 17-NOV-2009 (NJB)

#### Index_Entries

       find next segment in dla file

#### Link to routine dlafns_c source file dlafns_c.c

    Wed Apr  5 17:54:31 2017