Procedure

   dafgsr_c ( DAF, get summary/descriptor record ) 

   void dafgsr_c  ( SpiceInt        handle,
                    SpiceInt        recno,
                    SpiceInt        begin,
                    SpiceInt        end,
                    SpiceDouble   * data,
                    SpiceBoolean  * found  )

Abstract

   Read a portion of the contents of a summary record in a DAF file.

Required_Reading

   DAF

Keywords

   FILES

Brief_I/O

   VARIABLE  I/O  DESCRIPTION
   --------  ---  --------------------------------------------------
   handle     I   Handle of DAF.
   recno      I   Record number.
   begin      I   First word to read from record.
   end        I   Last word to read from record.
   data       O   Contents of record.
   found      O   SPICETRUE if record is found.

Detailed_Input

   handle      is the handle associated with a DAF.

   recno       is the record number of a particular double precision
               record within the DAF, whose contents are to be read. DAF
               record numbers start at 1.

   begin       is the first word in the specified record to be returned.
               Word numbers range from 1 to 128.

   end         is the final word in the specified record to be returned.
               Word numbers range from 1 to 128.

Detailed_Output

   data        contains the specified portion (from `begin' to `end',
               inclusive) of the specified record from the specified
               file.

   found       is SPICETRUE when the specified record is found, and is
               SPICEFALSE otherwise.

Parameters

   None.

Exceptions

   1)  If `handle' does not belong to any file that is currently open,
       an error is signaled by a routine in the call tree of this
       routine.

   2)  If an error occurs while reading the record, the error is
       signaled by a routine in the call tree of this routine.

   3)  Bad values for `begin' and `end' ( begin < 1, end > 128,
       end < begin ) are not diagnosed. See -Particulars and
       -Restrictions for the effect of this routine in this case.

Files

   The input `handle' must refer to a DAF file that is open for read
   or write access.

Particulars

   dafgsr_c checks the DAF record buffer to see if the requested
   record can be returned without actually reading it from
   external storage. If not, it reads the record and stores
   it in the buffer, typically removing another record from
   the buffer as a result.

   Once in the buffer, the specified portion of the record is
   returned, using the following control loop.

      for ( j = 0, i = max(1,begin);  i <= min(128,end);  i++, j++ )
      {
         data[j] =  buffered_DAF_record[i];
      }

   Therefore bad values for `begin' and `end' (begin < 1, end < begin,
   etc.) are not signaled as errors, but result in the actions
   implied by the above.

Examples

   The following code fragment illustrates one way that dafgsr_c
   and dafwdr_ can be used to update part of a summary record.
   If the record does not yet exist, we can assume that it is
   filled with zeros.

      #include "SpiceUsr.h"
      #include "SpiceZfc.h"

      SpiceInt    size   = 128;
      SpiceInt    recno;
      SpiceInt    handle;
          .
          .
          .
      dafgsr_c ( handle, recno, 1, 128, drec, &found );

      if ( !found )
      {
          cleard_ ( &size, drec );
      }

      for ( i = first;  i <= last;  i++ )
      {
          drec[i] = new_value[i];
      }

      dafwdr_ ( &handle, &recno, drec );

   Note that since only entire records may be written using dafwdr_,
   the entire record needs to be read also.

Restrictions

   1)  Bad values for `begin' and `end' ( begin < 1, end > 128,
       end < begin ) are not signaled as errors. The effects of
       such assignments on the returned data are defined by the
       following control structure:

          for ( j = 0, i = max(1,begin);  i <= min(128,end);  i++, j++ )
          {
             data[j] =  buffered_DAF_record[i];
          }

Literature_References

   None.

Author_and_Institution

   N.J. Bachman        (JPL)
   J. Diaz del Rio     (ODC Space)
   F.S. Turner         (JPL)

Version

   -CSPICE Version 1.1.0, 08-AUG-2021 (JDR) (NJB)

       Bug fix: now the number of records read is not incremented once
       it reaches intmax_c, if it does.

       Edited the header to comply with NAIF standard.

       Updated -Detailed_Input, -Exceptions, -Particulars and -Restrictions
       sections.

   -CSPICE Version 1.0.0, 17-JUN-2009 (NJB) (FST)

Index_Entries

   read DAF summary record