StepAttacks[] is misdesigned, the color dependance is specific
to pawns, and trying to generalise to king and knights, proves
neither useful nor convinient in practice.
So this patch reformats the code with the following changes:
- Use PieceType instead of Piece in attacks_() functions
- Use PseudoAttacks for KING and KNIGHT
- Rename StepAttacks[] into PawnAttacks[]
Original patch and idea from Alain Savard.
No functional change.
Closes#1086
This patch removes the empty rows at the beginning and at the end of
MobilityBonus[] and Protector[] arrays:
• reducing the size of MobilityBonus from 768 bytes to 512 bytes
• reducing the size of Protector from 1024 to 512 bytes
Also adds some comments and cleaner code for the arrays in pawns.cpp
No speed penalty (measured speed-up of 0.4%).
No functional change.
Closes#1018
Order the enum and the array the same way they appear around line 250.
Makes it much easier to follow.
Add comments in the array definition and critical rows.
Use same terminology as elsewhere in pawns.cpp
No functional change.
This patch tweaks some pawn values to favor flank attacks.
The first part of the patch increases the midgame psqt values of external pawns to launch more attacks (credits to user GuardianRM for this idea), while the second part increases the endgame connection values for pawns on upper ranks.
Passed STC:
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 34997 W: 6328 L: 6055 D: 22614
and LTC:
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 13844 W: 1832 L: 1650 D: 10362
Bench: 5884767
Rename shift_bb() to shift(), and DELTA_S to SOUTH, etc.
to improve code readability, especially in evaluate.cpp
when they are used together:
old b = shift_bb<DELTA_S>(pos.pieces(PAWN))
new b = shift<SOUTH>(pos.pieces(PAWN))
While there fix some small code style issues.
No functional change.
If the opponent has a cramped position, opening a file often
helps him/her to exchange pieces, so it makes sense to reduce
the space bonus if there are open files.
Credits: Leonardo Ljubičić for the strategic idea, Alain Savard for the
implementation of the open files calculation, "CrunchyNYC" for the
compensation of the numerator.
STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 49112 W: 9239 L: 8900 D: 30973
LTC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 89415 W: 12014 L: 11601 D: 65800
Bench: 7591630
On top of the usual conditions
a) some opponent in front (but no lever)
b) some neighbours (in front) (but no neighbour behind or same rank)
c) < rank_5
to find out if a pawn is backward we look at the squares in front of this pawn to reach the same rank as the next neighbour.
In current master, a pawn is backward if any of those squares is controlled by an enemy pawn on an adjacent file
In this version, a pawn is ALSO backward if any of those squares is occupied by an enemy pawn.
STC:
http://tests.stockfishchess.org/tests/view/56fe7efd0ebc59301a3541f1
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 19051 W: 3557 L: 3433 D: 12061
LTC:
http://tests.stockfishchess.org/tests/view/56febc2d0ebc59301a354209
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 40810 W: 5619 L: 5526 D: 29665
Bench: 7525245
Resolves#614
Also a speedup(about 1%) on 64-bit w/o hardware popcnt
Retire Max15 and Full template parameters
(Contributed by Marco Costalba)
Now that we have just SW and HW versions, use
template default parameter to get rid of explicit
template parameters.
Retire bitcount.h and move the only defined
function to bitboard.h
No functional change
Resolves#620
Also inline defintions of SpaceMask and CenterBindMask.
Verified from assembly that compiler computes the values
at compile time, so it is also theoretical faster.
While there factor out scale factor evaluation.
No functional change.
Using less parameters and code to compute Threats
Includes also a few spacing edits.
Run as a simplification.
Passed STC 10+0.1
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 18879 W: 3725 L: 3600 D: 11554
Passed LTC 60+0.4
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 74116 W: 11001 L: 10958 D: 52157
bench: 8004751
Use Position::square and Position::squares instead.
This allow us to remove king_square(), simplify
endgames and to have more naming uniformity.
Moreover, this is a prerequisite step in case
in the future we decide to retire piece lists
altoghter and use pop_lsb() to loop across
pieces and serialize the moves. In this way
we just need to change definition of Position::square
to something like:
template<PieceType Pt> inline
Square Position::square(Color c) const {
return lsb(byColorBB[c]);
}
No functional change.
Small speed-up in pawn.cpp
Results for 10 tests for each version:
Base Test Diff
Mean 1435636 1445238 -9602
StDev 22576 23189 1848
p-value: 1
speedup: 0.007
No functional change
Resolves#295
There's no reason to define it as a Bitboard, so for consistency, use bool.
This is even a speedup on my machine: i7-3770k, using gcc 4.9.1 (linux):
stat test master diff
mean 2,341,338 2,327,998 13,134
stdev 15,765 14,717 5,405
speedup 0.56%
P(speedup>0) 100.0%
No functional change.
Resolves#298
minKingPawnDistance is used only as local variable in one place so we don't need it to be part of "Pawns::Entry" structure.
No functional change.
Resolves#277
