It is not equivalent because the check for the
50 moves rule get badly affected.
// Draw by the 50 moves rule?
if (st->rule50 > 100 || (st->rule50 == 100 && !is_check()))
return true;
So we _really_ need two counters.
Thanks to Joona and Tord to be patience with a silly guy ;-)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
In case we reach ply == PLY_MAX we exit the function
writing
pv[PLY_MAX] = MOVE_NONE;
And because SearchStack is defined as:
struct SearchStack {
Move pv[PLY_MAX];
Move currentMove;
.....
We end up with the unwanted assignment
SearchStack.currentMove = MOVE_NONE;
Fortunatly this is harmless because currentMove is not used where
extarct_pv() is called. But neverthless this is a bug that
needs to be fixed.
Thanks to Uri Blass for spotting out this.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Null moves can artificially create a repetition
draw where instead there is no one.
So use a second counter to reset history after
a null move.
Idea from Joona.
After 999 games at 1+0
Mod vs Orig +238 =553 -208 51.50% 514.5/999 +10 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
When pondering InfiniteSearch == false but myTime == 0 so that
NodesBetweenPolls = 1000 instead of the standard.
The patch fixes the bug and is more robust because checks
directly myTime for a non-zero value, without relying on
an indirect test (InfiniteSearch in this case).
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Instead of checking the time every 100 nodes in the last second,
and every 1000 nodes in the last five seconds, Stockfish now checks
every 1000 nodes in the last second and every 5000 nodes in the last
five seconds. This was tested in 1036 games at a time control of
40 moves/10 seconds, and no losses on time occured.
Also fixed a bug pointed out by Marco: In infinite mode, myTime
is actually 0, but of course we still don't want to check the time
more frequently than the standard once per 30000 nodes in this
case.
In RootMoveList c'tor we allocate a search stack and then
call directly qsearch.
There is called init_node() that clears all the fields of the search
stack array that refers to current ply but not the the killer moves.
The killer moves cleared correspond to ply+2.
In id_loop() this is not a problem because killer moves of
corresponding ply are cleared anyway few instructions later,
but in RootMoveList c'tor we leave them uninitialized.
This patch fixes this very old bug. It comes direclty
from Glaurung age.
Bug spotted by Valgrind.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
In particular don't use an array of StateInfo, this
avoids a possible overflow and is in any case redundant.
Also pass as argument the pv[] array size to avoid a second
possible overflow on this one.
Fix suggested by Joona.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
It turned out that we used do_move_bb to update the king and rook
bitboards when making and unmaking castling moves, which obviously
doesn't work in Chess960, where the source and destination squares
for the king or rook could be identical.
No functional change in normal chess.
If an enemy piece is defended by a pawn don't give the
extra mobility bonus in case we attack it.
Joona says that "Paralyzing pawn" is usually worth of nothing.
On Joona QUAD after 964 games:
Orig - Patch_2: 191 - 218 - 555 (+ 10 elo)
On my PC after 999 games at 1+0:
Mod vs Orig +227 =550 -222 50.25% 502.0/999 +2 ELO
In both cases we tested against the original version (without
increased mobility), not against the previous patch that instead
seems to fail on Joona QUAD:
Orig vs. Prev.Patch: 237 - 217 - 627 (-6 elo)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Now in mobility we count enemy attacked pieces as
empty squares.
With this patch we try to give an higher score to positions
where the number of attacked pieces is higher.
After 999 games at 1+0
Mod vs Orig +262 =517 -219 52.15% 520.5/998 +15 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
They are pawn structure invariant so has a sense to
store togheter with pawn info instead of recalculating
them each time evaluate() is called.
Speed up is around 1%
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This satisfies a specific user request of 28/8/2009
"The only issue I have is that during multiPV analysis, the depth 1
best move score is not reported by the engine (reporting for the best
move begins at depth 2). I need it at depth 1 also. Would it be
possible to make this modification in future versions? This would be
of great help as otherwise I will have to use a lesser engine.
The goal of my project is to calculate the ELO performance in a game
and also the ELO rating of individual moves. For this I need depth 1
scores for lower rated performances. I intend to distribute the program
for free upon completion.
Thanks, Jack Welbourne"
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Is used only in weight_option() so inline there.
Unroll color loop also for evaluate_space() and
finally also some assorted code style fixes.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Use templates to manually unroll the loops so that
many values could be calculated at compile time or at
runtime but with a fast direct memory access instead of
an indirect one.
This change gives a speed up of 3.5 % on pgo build !!! :-)
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Move to what we already do in generate_piece_moves()
This simple patch gives a spped up of 1.4% !!
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Use equivalent Windows function _ftime() instead.
This patch also removes two long standing warnings
under MSVC.
No functional change and no change for non-Windows systems.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This patch make the piece list always terminated by SQ_NONE,
so that we can use a simpler and faster loop in move
generation.
Speedup is about 0.6%.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
With this very simple patch we get a speed boost
of 0.8% on my PC !
Sometime we find the most complex tricks to increase speed
when instead the best results come from the simplest solutions.
No functional change of course ;-)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
A better and more specific name. Also a bit of code reshuffle.
Verified No functional change and No performance change
for the whole series.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Rewrite in the form normally used in other similar
functions like generate_pawn_noncaptures()
This allow an easier reading of the pawn moves generators
and simplify a bit the code.
No functional change (tested on more then 100M nodes).
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
A bunch of trivial code style and comment fixes.
Among them there is a real fix for a subtle case
involving promotion moves.
We currently check that a pawn push to 8/1th rank
must be a promotion, but we don't check the contary,
i.e. that a pawn push on a different rank must NOT be
a promotion. Note that, funny enough, we perform this
control for all the other pieces, but not for the pawns!
This patch fixes this really corner case.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Remove a bunch of difficult and tricky code to test
legality of castle and ep moves and instead use a slower
but simpler check against the list of generated legal moves.
Because these moves are very rare the performance impact
is small but code semplification is ver big: almost 100 lines
of difficult code removed !
No functionality change. No performance change (strangely enough
there is no even minimal performance regression in pgo builds but
instead a slightly and unexpected increase).
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
In qsearch at depth 0 we generate only captures and checks.
Queen promotion moves are generated among the captures, but
under-promotion moves (both captures and non-captures) are
never generated even if they could give a discovery check.
This patch fixes this limitation extending generate_pawn_noncaptures()
to generate also check moves when required.
Apart for adding the (rare) case of an under-promotion that gives
discovery check, the patch is also a good cleanup because removes
generate_pawn_checks() altoghter.
This patch does the code clean-up but not enables the functional
change so to allow an easier debug.
No functional change and no performance change (actually a very
very small speed increase).
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
We are generating also king moves that give check !
Of course these moves are illegal so are in any case
filtered out in MovePicker. Neverthless we should avoid
to generate them.
Also simplify a bit the code.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Idea from Joona.
After 999 games at 1+0 on my Intel Core 2 Duo
Orig - Mod: +215 =538 -226 (+11 ELO)
On Joona QUAD after 845 games at 1+0
Orig - Mod: 151 - 181 - 513 (+13 elo)
So it seems a good change !
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
When a node fails low and bestValue is still equal to
the original static node evaluation, then save this
in TT along with usual info.
This will allow us to avoid a future costly evaluation() call.
This patch extends to failed low nodes what we already do
for failed high ones.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
