Procedure

     LNKFSL ( LNK, free sublist of a list  )

     SUBROUTINE LNKFSL ( HEAD, TAIL, POOL )

Abstract

     Free a specified sublist in a list.

Required_Reading

     None.

Keywords

     LIST

Declarations

     IMPLICIT NONE

     INTEGER               LBPOOL
     PARAMETER           ( LBPOOL = -5 )

     INTEGER               HEAD
     INTEGER               TAIL
     INTEGER               POOL ( 2,  LBPOOL : * )

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     HEAD,
     TAIL       I   Head and tail nodes of a sublist to be freed.
     POOL      I-O  A doubly linked list pool.

Detailed_Input

     HEAD,
     TAIL     are, respectively, the head and tail nodes of a
              sublist to be extracted.

     POOL     is a doubly linked list pool.

Detailed_Output

     POOL     is the input pool, with the following
              modifications:

                 -- All of the nodes of the sublist bounded by
                    HEAD and by TAIL have now been returned to
                    the free list.

                 If on input, HEAD was preceded by the node
                 PREV, and tail was followed by the node
                 NEXT, then on output

                 -- The successor of PREV is NEXT.
                 -- The predecessor of NEXT is PREV.

Parameters

     LBPOOL   is the lower bound of the column indices of the POOL
              array. The columns indexed LBPOOL to 0 are reserved
              as a control area for the pool.

Exceptions

     1)  If either of HEAD or TAIL are not valid node numbers, the
         error SPICE(INVALIDNODE) is signaled. POOL will not be
         modified.

     2)  If either of HEAD or TAIL are valid node numbers but are not
         allocated, the error SPICE(UNALLOCATEDNODE) is signaled. POOL
         will not be modified.

     3)  If TAIL cannot be reached by forward traversal of the list
         containing HEAD, the error SPICE(INVALIDSUBLIST) is signaled.
         POOL will not be modified.

Files

     None.

Particulars

     Deleting a sublist from a list returns all of the nodes in
     the sublist to the free list.

     To remove a sublist from a list and retain the sublist
     as a second list, use the routine LNKXSL ( LNK, extract
     sublist ).

Examples

     1)  Let POOL be a doubly linked list pool containing the list

            1002 <--> 3 <--> 7 <--> 88 <--> 2

         To delete the sublist

            3 <--> 7 <--> 88

         the call

            CALL LNKFSL ( 3, 88, POOL )

         can be used. The resulting list will be:

            1002 <--> 2

         The nodes 3, 7, and 88 will now be on the free list.



     2)  Let POOL be a doubly linked list pool containing the list

            1002 <--> 3 <--> 7 <--> 88 <--> 2

         To free the entire list, the call

            CALL LNKFSL ( 1002, 2, POOL )

         should be used.

Restrictions

     1)  Linked list pools must be initialized via the routine
         LNKINI. Failure to initialize a linked list pool
         will almost certainly lead to confusing results.

Literature_References

     None.

Author_and_Institution

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

Version

    SPICELIB Version 1.0.1, 24-NOV-2021 (JDR)

        Edited the header to comply with NAIF standard.

    SPICELIB Version 1.0.0, 19-DEC-1995 (NJB) (WLT)