Procedure

     DASRCR ( DAS, remove comment records )

     SUBROUTINE DASRCR ( HANDLE, N )

Abstract

     Decrease the size of the comment area in a DAS file to reclaim
     space freed by the removal of a specified number of comment
     records.

Required_Reading

     DAS

Keywords

     DAS
     FILES
     UTILITY

Declarations

     IMPLICIT NONE

     INTEGER               HANDLE
     INTEGER               N

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     HANDLE     I   A DAS file handle.
     N          I   Number of comment records to remove.

Detailed_Input

     HANDLE   is the handle of an existing DAS file opened for
              comment area modification by DASOPC.

     N        is the number of records to remove from the end of
              the comment area. of the specified file. If NCOMR
              is the number of comment records present in the
              file on input, then on output the number of comment
              records will be MAX ( 0,  NCOMR - N ).

Detailed_Output

     None. See $Particulars for a description of the effect of this
     routine.

Parameters

     None.

Exceptions

     1)  If the input handle is invalid, an error is signaled by a
         routine in the call tree of this routine.

     2)  If an I/O error occurs during the removal process, the error
         is signaled by a routine in the call tree of this routine. The
         DAS file will probably be corrupted in this case.

Files

     See the description of the argument HANDLE in $Detailed_Input.

Particulars

     This routine is used to reclaim freed space in the comment area
     of a DAS file subsequent to removal of comments from the file.
     Any existing directory records and data records will be shifted
     up by N records.

     This routine updates the file record of the specified DAS file
     to reflect the addition of records to the file's comment area.
     Also, the file summary obtainable from DASHFS will be updated to
     reflect the addition of comment records.

     The disk space occupied by the specified DAS file will not
     decrease as a result of calling this routine, but the number of
     records occupied by meaningful data will decrease. The useful
     records in the file can be copied by DAS routines to create a
     new, smaller file which contains only the meaningful data.

     This routine may be used only on existing DAS files opened by
     DASOPC.

     The association of DAS logical addresses and data within the
     specified file will remain unaffected by use of this routine.

     Normally, SPICELIB applications will not call this routine
     directly, but will remove comments by calling DASRC.

     This routine has an inverse DASACR, which appends a specified
     number of records to the end of the comment area.

Examples

     C
     C     Open an existing DAS file for modification of
     C     the comment area. We'll presume that the file
     C     contains 20 comment records.
     C
           CALL DASOPC ( DAS, HANDLE )

     C
     C     Remove the last 10 comment records from the file.
     C
           CALL DASRCR ( HANDLE, 10  )

     C
     C     Close the file.
     C
           CALL DASCLS ( HANDLE )

Restrictions

     1)  The DAS file must have a binary file format native to the host
         system.

Literature_References

     None.

Author_and_Institution

     N.J. Bachman       (JPL)
     J. Diaz del Rio    (ODC Space)
     W.L. Taber         (JPL)

Version

    SPICELIB Version 1.3.0, 02-JUN-2021 (JDR)

        Added IMPLICIT NONE statement.

        Edited the header to comply with NAIF standard.

    SPICELIB Version 1.2.0, 05-FEB-2015 (NJB)

        Updated to support integration with the handle
        manager subsystem.

        Cleaned up use of unnecessary variables and unneeded
        declarations.

    SPICELIB Version 1.0.0, 15-NOV-1992 (NJB) (WLT)