PTRI_SPLAY_LINKS
TriSubtreePredecessor(
  IN  PTRI_SPLAY_LINKS Links
  );

Routine Description:

    This SubTreePredecessor function takes as input a pointer to a splay link
    in a tree and returns a pointer to the predecessor of the input node of
    the subtree rooted at the input node.  If there is not a predecessor,
    the return value is NULL.

Arguments:

    Links - Supplies the pointer to a splay link in a tree

Return Values:

    PRTI_SPLAY_LINKS - Returns a pointer to the predecessor in the subtree