Rename to insertion_sort so to avoid confusion
with std::sort, also move it to movepicker.cpp
and use the bit slower std::stable_sort in
search.cpp where it is used in not performance
critical paths.
No functional change.
Surprisingly this rare case was not considered
when scoring a capture.
Also take in account that in the promotion case
we gain a new piece (typically a queen) but we
lose the promoting pawn.
These small issues were present since Glaurung times!
Found while browsing DiscoCheck sources
bench: 5400063
Handling of History and Gains is almost the same, with
the exception of the update logic, so unify both
classes under a single Stats struct.
No functional change.
Templetize MovePicker::next_move() member function instead. It
is easier and we also avoid the forwarding of MovePicker() c'tor
arguments in the common case.
Suggested by Rein Halbersma.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Instead of by SEE. Almost no ELO change but it is
a bit easier and is a more natural choice given
that good captures are ordered in the same way.
After 10424 games
Mod vs Orig 1639 - 1604 - 7181 ELO +1 (+-3.8)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Integrate TT_MOVE step into the first state. This allows to
avoid the first call to next_phase() in case of a TT move.
And use overflow detection instead of the bunch of STOP_XX
states to detect end of moves.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Almost no functional change because multiple recaptures
to same square are very rare, but neverthless it seems
the correct thing to do.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
The aim is to have shorter names without losing
readibility but, if possible, increasing it.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Follow the suggested Qt style:
http://doc.qt.nokia.com/qq/qq13-apis.html
It seems to me simpler and easier to read.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Consider negative captures as good if
still enough to reach beta.
After 7502 games:
Mod vs Orig 1225 - 1158 - 5119 ELO +3 (+- 4.5)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
They don't add any value given that the corresponding
table has global visibility anyhow.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Functional change due to the fact that now pick_best() is
stable, but should be no change in strenght.
Example code and ideas by Rein Halbersma.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
We miss to account as a capture a promotion capture !
Incredible bug in this critical function that is here
since a long time (b50921fd5c of 21/10/2009 !!)
This patch fixes the bug and readds the faster
move_is_capture_or_promotion() that slightly increases
overall speed.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This avoids search explosion in qsearch for some
patological cases like:
r1n1n1b1/1P1P1P1P/1N1N1N2/2RnQrRq/2pKp3/3BNQbQ/k7/4Bq2 w - - 0 1
After 9078 games 20"+0.1 QUAD:
Mod vs Orig 1413 - 1319 - 6346 ELO +3 (+- 4)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
In case we have more than one promotion move, prefer
the one that captures the biggest piece.
Almost no functional change, anyhow I don't expect any
ELO change, it is just the correct thing to do.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
It seems much worst in number of nodes seacrhed to reach
the depth and anyhow does not give any advantage to the
Onno's oroginal one.
So revert by now and perhaps readd when we find something
clearly better.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
After 12613 games at 20"+0.1 on QUAD
Mod vs Orig 1870 - 1863 - 8880 ELO +0 (+- 3.3)
So no performance change but it is a code semplification
and also is more easy to understand.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Here the idea is to test probcut not only after bad
captures, but after any bad move, i.e. any move that
leaves the opponent with a good capture.
Ported by a patch from Onno, the difference from
original version is that we have moved probcut after
null search.
After 7917 games 4 threads 20"+0.1
Mod vs Orig: 1261 - 1095 - 5561 ELO +7 (+- 4.2) LOS 96%
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
