Procedure

     LNKNFN ( LNK, number of free nodes )

     INTEGER FUNCTION LNKNFN ( POOL )

Abstract

     Return the number of free nodes in a doubly linked list pool.

Required_Reading

     None.

Keywords

     LIST

Declarations

     IMPLICIT NONE

     INTEGER               LBPOOL
     PARAMETER           ( LBPOOL = -5 )

     INTEGER               POOL ( 2,  LBPOOL : * )

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     POOL       I   A doubly linked list pool.
     LBPOOL     P   Lower bound of pool column indices.

     The function returns the number of free nodes in the pool.

Detailed_Input

     SIZE     is the number of nodes in the pool.

     POOL     is a doubly linked list pool.

Detailed_Output

     The function returns the number of free nodes in the pool.

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

     Error free.

Files

     None.

Particulars

     This routine allows the caller to find the number of free nodes
     available in a doubly linked list pool, without having to make
     use of knowledge of the internal structure of the pool.

     Routines that allocate nodes can use this routine to determine
     how many nodes can be allocated safely---an attempt to allocate
     a node when no free nodes are available causes a SPICELIB error
     to be signaled.

Examples

     1)  Let POOL be a doubly linked list pool containing 5 nodes.
         If POOL contains the list

            4 <--> 5 <--> 1 <--> 2


         and the node 3 is unallocated, then the function reference

            NFREE  =  LNKNFN ( POOL )


         will assign the value 1 to NFREE.

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)