hbitmap: add hbitmap_merge
We add a bitmap merge operation to assist in error cases where we wish to combine two bitmaps together. This is algorithmically O(bits) provided HBITMAP_LEVELS remains constant. For a full bitmap on a 64bit machine: sum(bits/64^k, k, 0, HBITMAP_LEVELS) ~= 1.01587 * bits We may be able to improve running speed for particularly sparse bitmaps by using iterators, but the running time for dense maps will be worse. We present the simpler solution first, and we can refine it later if needed. Signed-off-by: NJohn Snow <jsnow@redhat.com> Reviewed-by: NMax Reitz <mreitz@redhat.com> Reviewed-by: NEric Blake <eblake@redhat.com> Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com> Message-id: 1429314609-29776-8-git-send-email-jsnow@redhat.com Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com> Signed-off-by: NKevin Wolf <kwolf@redhat.com>
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