/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, 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 "bitcount.h"
#include "pawns.h"
#include "position.h"
+#include "thread.h"
namespace {
// Unsupported pawn penalty
const Score UnsupportedPawnPenalty = S(20, 10);
+ // Center bind bonus: Two pawns controlling the same central square
+ const Bitboard CenterBindMask[COLOR_NB] = {
+ (FileDBB | FileEBB) & (Rank5BB | Rank6BB | Rank7BB),
+ (FileDBB | FileEBB) & (Rank4BB | Rank3BB | Rank2BB)
+ };
+
+ const Score CenterBind = S(16, 0);
+
// Weakness of our pawn shelter in front of the king by [distance from edge][rank]
const Value ShelterWeakness[][RANK_NB] = {
- { V(100), V(13), V(24), V(64), V(89), V( 93), V(104) },
- { V(110), V( 1), V(29), V(75), V(96), V(102), V(107) },
- { V(102), V( 0), V(39), V(74), V(88), V(101), V( 98) },
- { V( 88), V( 4), V(33), V(67), V(92), V( 94), V(107) } };
+ { V( 99), V(20), V(26), V(54), V(85), V( 92), V(108) },
+ { V(117), V( 1), V(27), V(71), V(94), V(104), V(118) },
+ { V(104), V( 4), V(51), V(76), V(82), V(102), V( 97) },
+ { V( 80), V(12), V(43), V(65), V(88), V( 91), V(115) } };
// Danger of enemy pawns moving toward our king by [type][distance from edge][rank]
const Value StormDanger[][4][RANK_NB] = {
- { { V( 0), V( 63), V( 128), V(43), V(27) },
- { V( 0), V( 62), V( 131), V(44), V(26) },
- { V( 0), V( 59), V( 121), V(50), V(28) },
- { V( 0), V( 62), V( 127), V(54), V(28) } },
- { { V(24), V( 40), V( 93), V(42), V(22) },
- { V(24), V( 28), V( 101), V(38), V(20) },
- { V(24), V( 32), V( 95), V(36), V(23) },
- { V(27), V( 24), V( 99), V(36), V(24) } },
- { { V( 0), V( 0), V( 81), V(16), V( 6) },
- { V( 0), V( 0), V( 165), V(29), V( 9) },
- { V( 0), V( 0), V( 163), V(23), V(12) },
- { V( 0), V( 0), V( 161), V(28), V(13) } },
- { { V( 0), V(-296), V(-299), V(55), V(25) },
- { V( 0), V( 67), V( 131), V(46), V(21) },
- { V( 0), V( 65), V( 135), V(50), V(31) },
- { V( 0), V( 62), V( 128), V(51), V(24) } } };
+ { { V( 0), V( 65), V( 126), V(36), V(30) },
+ { V( 0), V( 55), V( 135), V(36), V(23) },
+ { V( 0), V( 47), V( 116), V(45), V(26) },
+ { V( 0), V( 62), V( 127), V(57), V(34) } },
+ { { V(21), V( 45), V( 93), V(50), V(19) },
+ { V(23), V( 24), V( 105), V(41), V(13) },
+ { V(23), V( 36), V( 101), V(38), V(20) },
+ { V(30), V( 19), V( 110), V(41), V(27) } },
+ { { V( 0), V( 0), V( 81), V(14), V( 4) },
+ { V( 0), V( 0), V( 169), V(30), V( 3) },
+ { V( 0), V( 0), V( 168), V(24), V( 5) },
+ { V( 0), V( 0), V( 162), V(26), V(10) } },
+ { { V( 0), V(-283), V(-298), V(57), V(29) },
+ { V( 0), V( 63), V( 137), V(42), V(18) },
+ { V( 0), V( 67), V( 145), V(49), V(33) },
+ { V( 0), V( 62), V( 126), V(53), V(21) } } };
// 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 Value MaxSafetyBonus = V(257);
+ const Value MaxSafetyBonus = V(258);
#undef S
#undef V
lever = theirPawns & pawnAttacksBB[s];
// Test for backward pawn.
- // If the pawn is passed, isolated, or connected it cannot be
+ // If the pawn is passed, isolated, connected or a lever it cannot be
// backward. If there are friendly pawns behind on adjacent files
- // or if it can capture an enemy pawn it cannot be backward either.
- if ( (passed | isolated | connected)
- || (ourPawns & pawn_attack_span(Them, s))
- || (pos.attacks_from<PAWN>(s, Us) & theirPawns))
+ // it cannot be backward either.
+ if ( (passed | isolated | lever | connected)
+ || (ourPawns & pawn_attack_span(Them, s)))
backward = false;
else
{
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[Us];
+ score += popcount<Max15>(b) * CenterBind;
+
return score;
}
namespace Pawns {
-/// init() initializes some tables used by evaluation. Instead of hard-coded
-/// tables, when makes sense, we prefer to calculate them with a formula to
-/// reduce independent parameters and to allow easier tuning and better insight.
+/// Pawns::init() initializes some tables needed by evaluation. Instead of using
+/// hard-coded tables, when makes sense, we prefer to calculate them with a formula
+/// to reduce independent parameters and to allow easier tuning and better insight.
void init()
{
for (Rank r = RANK_2; r < RANK_8; ++r)
{
int bonus = Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0);
- Connected[opposed][phalanx][r] = make_score(bonus / 2, bonus >> opposed);
+ bonus >>= opposed;
+ Connected[opposed][phalanx][r] = make_score( 3 * bonus / 2, bonus);
}
}
-/// probe() takes a position as input, computes a Entry object, and returns a
-/// pointer to it. The result is also stored in a hash table, so we don't have
-/// to recompute everything when the same pawn structure occurs again.
+/// Pawns::probe() looks up the current position's pawns configuration in
+/// the pawns hash table. It returns a pointer to the Entry if the position
+/// is found. Otherwise a new Entry is computed and stored there, so we don't
+/// have to recompute all when the same pawns configuration occurs again.
-Entry* probe(const Position& pos, Table& entries) {
+Entry* probe(const Position& pos) {
Key key = pos.pawn_key();
- Entry* e = entries[key];
+ Entry* e = pos.this_thread()->pawnsTable[key];
if (e->key == key)
return e;
Bitboard pawns = pos.pieces(Us, PAWN);
if (pawns)
- while (!(DistanceRingsBB[ksq][minKingPawnDistance[Us]++] & pawns)) {}
+ while (!(DistanceRingBB[ksq][minKingPawnDistance[Us]++] & pawns)) {}
if (relative_rank(Us, ksq) > RANK_4)
return make_score(0, -16 * minKingPawnDistance[Us]);
projects / stockfish / blobdiff