Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#include <cassert>
#include "bitboard.h"
-#include "bitcount.h"
#include "pawns.h"
#include "position.h"
#include "thread.h"
#define V Value
#define S(mg, eg) make_score(mg, eg)
- // Doubled pawn penalty by file
- const Score Doubled[FILE_NB] = {
- S(13, 43), S(20, 48), S(23, 48), S(23, 48),
- S(23, 48), S(23, 48), S(20, 48), S(13, 43) };
-
// Isolated pawn penalty by opposed flag and file
const Score Isolated[2][FILE_NB] = {
- { S(37, 45), S(54, 52), S(60, 52), S(60, 52),
- S(60, 52), S(60, 52), S(54, 52), S(37, 45) },
- { S(25, 30), S(36, 35), S(40, 35), S(40, 35),
- S(40, 35), S(40, 35), S(36, 35), S(25, 30) } };
+ { S(31, 36), S(45, 41), S(50, 41), S(50, 41),
+ S(50, 41), S(50, 41), S(45, 41), S(31, 36) },
+ { S(21, 24), S(30, 28), S(33, 28), S(33, 28),
+ S(33, 28), S(33, 28), S(30, 28), S(21, 24) } };
// Backward pawn penalty by opposed flag
- const Score Backward[2] = { S(67, 42), S(49, 24) };
+ const Score Backward[2] = { S(56, 33), S(41, 19) };
+
+ // Unsupported pawn penalty for pawns which are neither isolated or backward,
+ // by number of pawns it supports [less than 2 / exactly 2].
+ const Score Unsupported[2] = { S(17, 8), S(21, 12) };
// Connected pawn bonus by opposed, phalanx, twice supported and rank
Score Connected[2][2][2][RANK_NB];
- // Levers bonus by rank
- const Score Lever[RANK_NB] = {
- S( 0, 0), S( 0, 0), S(0, 0), S(0, 0),
- S(20,20), S(40,40), S(0, 0), S(0, 0) };
-
- // Unsupported pawn penalty
- const Score UnsupportedPawnPenalty = S(20, 10);
+ // Doubled pawn penalty by file
+ const Score Doubled[FILE_NB] = {
+ S(11, 34), S(17, 38), S(19, 38), S(19, 38),
+ S(19, 38), S(19, 38), S(17, 38), S(11, 34) };
- const Score CenterBind = S(16, 0);
+ // Lever bonus by rank
+ const Score Lever[RANK_NB] = {
+ S( 0, 0), S( 0, 0), S(0, 0), S(0, 0),
+ S(17, 16), S(33, 32), S(0, 0), S(0, 0) };
// Weakness of our pawn shelter in front of the king by [distance from edge][rank]
const Value ShelterWeakness[][RANK_NB] = {
- { V( 97), V(21), V(26), V(51), V(87), V( 89), V( 99) },
- { V(120), V( 0), V(28), V(76), V(88), V(103), V(104) },
- { V(101), V( 7), V(54), V(78), V(77), V( 92), V(101) },
- { V( 80), V(11), V(44), V(68), V(87), V( 90), V(119) } };
+ { V( 97), V(21), V(26), V(51), V(87), V( 89), V( 99) },
+ { V(120), V( 0), V(28), V(76), V(88), V(103), V(104) },
+ { V(101), V( 7), V(54), V(78), V(77), V( 92), V(101) },
+ { V( 80), V(11), V(44), V(68), V(87), V( 90), V(119) } };
// Danger of enemy pawns moving toward our king by [type][distance from edge][rank]
const Value StormDanger[][4][RANK_NB] = {
- { { V( 0), V( 67), V( 134), V(38), V(32) },
- { V( 0), V( 57), V( 139), V(37), V(22) },
- { V( 0), V( 43), V( 115), V(43), V(27) },
- { V( 0), V( 68), V( 124), V(57), V(32) } },
- { { V(20), V( 43), V( 100), V(56), V(20) },
- { V(23), V( 20), V( 98), V(40), V(15) },
- { V(23), V( 39), V( 103), V(36), V(18) },
- { V(28), V( 19), V( 108), V(42), V(26) } },
- { { V( 0), V( 0), V( 75), V(14), V( 2) },
- { V( 0), V( 0), V( 150), V(30), V( 4) },
- { V( 0), V( 0), V( 160), V(22), V( 5) },
- { V( 0), V( 0), V( 166), V(24), V(13) } },
- { { V( 0), V(-283), V(-281), V(57), V(31) },
- { V( 0), V( 58), V( 141), V(39), V(18) },
- { V( 0), V( 65), V( 142), V(48), V(32) },
- { V( 0), V( 60), V( 126), V(51), V(19) } } };
+ { { V( 0), V( 67), V( 134), V(38), V(32) },
+ { V( 0), V( 57), V( 139), V(37), V(22) },
+ { V( 0), V( 43), V( 115), V(43), V(27) },
+ { V( 0), V( 68), V( 124), V(57), V(32) } },
+ { { V(20), V( 43), V( 100), V(56), V(20) },
+ { V(23), V( 20), V( 98), V(40), V(15) },
+ { V(23), V( 39), V( 103), V(36), V(18) },
+ { V(28), V( 19), V( 108), V(42), V(26) } },
+ { { V( 0), V( 0), V( 75), V(14), V( 2) },
+ { V( 0), V( 0), V( 150), V(30), V( 4) },
+ { V( 0), V( 0), V( 160), V(22), V( 5) },
+ { V( 0), V( 0), V( 166), V(24), V(13) } },
+ { { V( 0), V(-283), V(-281), V(57), V(31) },
+ { V( 0), V( 58), V( 141), V(39), V(18) },
+ { V( 0), V( 65), V( 142), V(48), V(32) },
+ { V( 0), V( 60), V( 126), V(51), V(19) } } };
// Max bonus for king safety. Corresponds to start position with all the pawns
// in front of the king and no enemy pawn on the horizon.
const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW);
const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE);
- const Bitboard CenterBindMask =
- Us == WHITE ? (FileDBB | FileEBB) & (Rank5BB | Rank6BB | Rank7BB)
- : (FileDBB | FileEBB) & (Rank4BB | Rank3BB | Rank2BB);
-
- Bitboard b, neighbours, doubled, supported, phalanx;
+ Bitboard b, neighbours, stoppers, doubled, supported, phalanx;
Square s;
- bool passed, isolated, opposed, backward, lever, connected;
+ bool opposed, lever, connected, backward;
Score score = SCORE_ZERO;
const Square* pl = pos.squares<PAWN>(Us);
const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)];
e->kingSquares[Us] = SQ_NONE;
e->semiopenFiles[Us] = 0xFF;
e->pawnAttacks[Us] = shift_bb<Right>(ourPawns) | shift_bb<Left>(ourPawns);
- e->pawnsOnSquares[Us][BLACK] = popcount<Max15>(ourPawns & DarkSquares);
+ e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares);
e->pawnsOnSquares[Us][WHITE] = pos.count<PAWN>(Us) - e->pawnsOnSquares[Us][BLACK];
// Loop through all pawns of the current color and score each pawn
e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);
// Flag the pawn
- neighbours = ourPawns & adjacent_files_bb(f);
- doubled = ourPawns & forward_bb(Us, s);
- opposed = theirPawns & forward_bb(Us, s);
- passed = !(theirPawns & passed_pawn_mask(Us, s));
- lever = theirPawns & pawnAttacksBB[s];
- phalanx = neighbours & rank_bb(s);
- supported = neighbours & rank_bb(s - Up);
- connected = supported | phalanx;
- isolated = !neighbours;
-
- // Test for backward pawn.
- // If the pawn is passed, isolated, lever or connected it cannot be
- // backward. If there are friendly pawns behind on adjacent files
- // or if it is sufficiently advanced, it cannot be backward either.
- if ( (passed | isolated | lever | connected)
- || (ourPawns & pawn_attack_span(Them, s))
- || (relative_rank(Us, s) >= RANK_5))
+ opposed = theirPawns & forward_bb(Us, s);
+ stoppers = theirPawns & passed_pawn_mask(Us, s);
+ lever = theirPawns & pawnAttacksBB[s];
+ doubled = ourPawns & forward_bb(Us, s);
+ neighbours = ourPawns & adjacent_files_bb(f);
+ phalanx = neighbours & rank_bb(s);
+ supported = neighbours & rank_bb(s - Up);
+ connected = supported | phalanx;
+
+ // A pawn is backward when it is behind all pawns of the same color on the
+ // adjacent files and cannot be safely advanced.
+ if (!neighbours || lever || relative_rank(Us, s) >= RANK_5)
backward = false;
else
{
- // We now know there are no friendly pawns beside or behind this
- // pawn on adjacent files. We now check whether the pawn is
- // backward by looking in the forward direction on the adjacent
- // files, and picking the closest pawn there.
- b = pawn_attack_span(Us, s) & (ourPawns | theirPawns);
- b = pawn_attack_span(Us, s) & rank_bb(backmost_sq(Us, b));
-
- // If we have an enemy pawn in the same or next rank, the pawn is
- // backward because it cannot advance without being captured.
- backward = (b | shift_bb<Up>(b)) & theirPawns;
+ // Find the backmost rank with neighbours or stoppers
+ b = rank_bb(backmost_sq(Us, neighbours | stoppers));
+
+ // The pawn is backward when it cannot safely progress to that rank:
+ // either there is a stopper in the way on this rank, or there is a
+ // stopper on adjacent file which controls the way to that rank.
+ backward = (b | shift_bb<Up>(b & adjacent_files_bb(f))) & stoppers;
+
+ assert(!backward || !(pawn_attack_span(Them, s + Up) & neighbours));
}
- assert(opposed | passed | (pawn_attack_span(Us, s) & theirPawns));
-
// Passed pawns will be properly scored in evaluation because we need
- // full attack info to evaluate passed pawns. Only the frontmost passed
+ // full attack info to evaluate them. Only the frontmost passed
// pawn on each file is considered a true passed pawn.
- if (passed && !doubled)
+ if (!(stoppers | doubled))
e->passedPawns[Us] |= s;
// Score this pawn
- if (isolated)
+ if (!neighbours)
score -= Isolated[opposed][f];
else if (backward)
score -= Backward[opposed];
else if (!supported)
- score -= UnsupportedPawnPenalty;
+ score -= Unsupported[more_than_one(neighbours & pawnAttacksBB[s])];
if (connected)
score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)];
b = e->semiopenFiles[Us] ^ 0xFF;
e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0;
- // Center binds: Two pawns controlling the same central square
- b = shift_bb<Right>(ourPawns) & shift_bb<Left>(ourPawns) & CenterBindMask;
- score += popcount<Max15>(b) * CenterBind;
-
return score;
}
void init()
{
- static const int Seed[RANK_NB] = { 0, 6, 15, 10, 57, 75, 135, 258 };
+ static const int Seed[RANK_NB] = { 0, 8, 19, 13, 71, 94, 169, 324 };
for (int opposed = 0; opposed <= 1; ++opposed)
for (int phalanx = 0; phalanx <= 1; ++phalanx)
{
int v = (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed;
v += (apex ? v / 2 : 0);
- Connected[opposed][phalanx][apex][r] = make_score(3 * v / 2, v);
+ Connected[opposed][phalanx][apex][r] = make_score(v, v * 5 / 8);
}
}
e->key = key;
e->score = evaluate<WHITE>(pos, e) - evaluate<BLACK>(pos, e);
- e->asymmetry = popcount<Max15>(e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]);
+ e->asymmetry = popcount(e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]);
return e;
}
if (pawns)
while (!(DistanceRingBB[ksq][minKingPawnDistance++] & pawns)) {}
- if (relative_rank(Us, ksq) > RANK_4)
- return make_score(0, -16 * minKingPawnDistance);
-
Value bonus = shelter_storm<Us>(pos, ksq);
// If we can castle use the bonus after the castling if it is bigger
projects / stockfish / blobdiff