These contain source code from an implementation of
an array based concurrent priority queue heap.
The TR describing this algorithm is TR560 titled
"An Efficient Algorithm for Concurrent Priority Queue Heaps." 
by Galen C. Hunt, Maged M. Michael, Srinivasan Parthasarathy
and Michael L. Scott.
It was implemented on on a SGI-Challenge 12 processor
(MIPS 4000 architecture) machine.
