At the low level, only unions can cause a set to grow. Of course, things
get interesting at the higher level when infinite (inverted) sets are
mixed in.
Instead of printing every representable member of an infinite set (ie,
up to element 63 in a set that can hold 64 elements), only those
elements up to one after the last non-member are listed. For example,
{...} - {2 3} -> {0 1 4 ...}
This makes reading (and testing!) infinite sets much easier.
Most of the set ops were always endian-agnostic since they were simply
operating on multiple bits in parallel, but individual element
add/remove/test was very endian-dependent. For the most part, this
didn't matter, but it does matter very much when loading external data
into a set or writing the data out (eg, for PVS).
I knew counting bits individually was slow, but it never really mattered
until now. However, I didn't expect such a dramatic boost just by going
to mapping bytes to bit counts. 16-bit words would be faster still, but
the 64kB lookup table would probably start hurting cache performance,
and 32-bit words (4GB table) definitely would ruin the cache. The
universe isn't big enough for 64-bits :)
After seeing set_size and thinking it redundant (thought it returned the
capacity of the set until I checked), I realized set_count would be a
much better name (set_count (node->successors) in qfcc does make much
more sense).
Having set_expand exposed is useful for loading data into a set.
However, it turns out there was a bug in its size calculation in that
when the requested set size was a multiple of SET_BITS (and greater than
the current set size), the new set size one be SET_BITS larger than
requested. There's now some tests for this :)
set_bits_t is now 64 bits for x86_64 machines (in linux, anyway). This gave
qfvis a huge speed boost: from ~815s to ~720s.
Also, expose some of the set internals so custom set operators can be
created.
Rather than prefixing free_ to the supplied name, suffix _freelist to the
supplied name. The biggest advantage of this is it allows the free-list to
be a structure member. It also cleans up the name-space a little.
Getting everything right with an enum proved to be too difficult if not
impossible. Also use better tests for equivalence and intersection.
Many more tests have been added. All pass :)
Also move the ALLOC/FREE macros from qfcc.h to QF/alloc.h (needed to for
set.c).
Both modules are more generally useful than just for qfcc (eg, set
builtins for ruamoko).
Bill Currie