X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fpawns.cpp;h=3ad88fb206aa011ece4fb6dca4c75acf17edb758;hb=351ef5c85b6d4b9c71e9da;hp=658a570079509e1aee2efad52bef96c887705e8f;hpb=9c9914d72aa68ac73bec163f7aea361e42bf9be5;p=stockfish
diff --git a/src/pawns.cpp b/src/pawns.cpp
index 658a5700..3ad88fb2 100644
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -17,27 +17,15 @@
along with this program. If not, see .
*/
-
-////
-//// Includes
-////
-
#include
-#include
+#include "bitboard.h"
#include "bitcount.h"
#include "pawns.h"
#include "position.h"
-
-////
-//// Local definitions
-////
-
namespace {
- /// Constants and variables
-
#define S(mg, eg) make_score(mg, eg)
// Doubled pawn penalty by opposed flag and file
@@ -73,39 +61,20 @@ namespace {
S(34,68), S(83,166), S(0, 0), S( 0, 0)
};
- #undef S
-}
-
-
-////
-//// Functions
-////
-
-/// PawnInfoTable c'tor and d'tor instantiated one each thread
-
-PawnInfoTable::PawnInfoTable() {
+ const Score PawnStructureWeight = S(233, 201);
- entries = new PawnInfo[PawnTableSize];
+ #undef S
- if (!entries)
- {
- std::cerr << "Failed to allocate " << (PawnTableSize * sizeof(PawnInfo))
- << " bytes for pawn hash table." << std::endl;
- Application::exit_with_failure();
+ inline Score apply_weight(Score v, Score w) {
+ return make_score((int(mg_value(v)) * mg_value(w)) / 0x100,
+ (int(eg_value(v)) * eg_value(w)) / 0x100);
}
- memset(entries, 0, PawnTableSize * sizeof(PawnInfo));
-}
-
-
-PawnInfoTable::~PawnInfoTable() {
-
- delete [] entries;
}
/// PawnInfoTable::get_pawn_info() takes a position object as input, computes
/// a PawnInfo 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
+/// in an hash table, so we don't have to recompute everything when the same
/// pawn structure occurs again.
PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const {
@@ -113,8 +82,7 @@ PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const {
assert(pos.is_ok());
Key key = pos.get_pawn_key();
- unsigned index = unsigned(key & (PawnTableSize - 1));
- PawnInfo* pi = entries + index;
+ PawnInfo* pi = probe(key);
// If pi->key matches the position's pawn hash key, it means that we
// have analysed this pawn structure before, and we can simply return
@@ -122,11 +90,11 @@ PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const {
if (pi->key == key)
return pi;
- // Clear the PawnInfo object, and set the key
- memset(pi, 0, sizeof(PawnInfo));
- pi->halfOpenFiles[WHITE] = pi->halfOpenFiles[BLACK] = 0xFF;
- pi->kingSquares[WHITE] = pi->kingSquares[BLACK] = SQ_NONE;
+ // Initialize PawnInfo entry
pi->key = key;
+ pi->passedPawns[WHITE] = pi->passedPawns[BLACK] = 0;
+ pi->kingSquares[WHITE] = pi->kingSquares[BLACK] = SQ_NONE;
+ pi->halfOpenFiles[WHITE] = pi->halfOpenFiles[BLACK] = 0xFF;
// Calculate pawn attacks
Bitboard wPawns = pos.pieces(PAWN, WHITE);
@@ -134,9 +102,12 @@ PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const {
pi->pawnAttacks[WHITE] = ((wPawns << 9) & ~FileABB) | ((wPawns << 7) & ~FileHBB);
pi->pawnAttacks[BLACK] = ((bPawns >> 7) & ~FileABB) | ((bPawns >> 9) & ~FileHBB);
- // Evaluate pawns for both colors
+ // Evaluate pawns for both colors and weight the result
pi->value = evaluate_pawns(pos, wPawns, bPawns, pi)
- evaluate_pawns(pos, bPawns, wPawns, pi);
+
+ pi->value = apply_weight(pi->value, PawnStructureWeight);
+
return pi;
}
@@ -145,20 +116,23 @@ PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const {
template
Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
- Bitboard theirPawns, PawnInfo* pi) const {
+ Bitboard theirPawns, PawnInfo* pi) {
+
+ const BitCountType Max15 = CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+
Bitboard b;
Square s;
File f;
Rank r;
bool passed, isolated, doubled, opposed, chain, backward, candidate;
Score value = SCORE_ZERO;
- const BitCountType Max15 = CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
const Square* ptr = pos.piece_list_begin(Us, PAWN);
// Loop through all pawns of the current color and score each pawn
while ((s = *ptr++) != SQ_NONE)
{
- assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
+ assert(pos.piece_on(s) == make_piece(Us, PAWN));
f = square_file(s);
r = square_rank(s);
@@ -166,27 +140,25 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
// This file cannot be half open
pi->halfOpenFiles[Us] &= ~(1 << f);
- // Our rank plus previous one. Used for chain detection.
+ // Our rank plus previous one. Used for chain detection
b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1));
- // Passed, isolated, doubled or member of a pawn
- // chain (but not the backward one) ?
+ // Flag the pawn as passed, isolated, doubled or member of a pawn
+ // chain (but not the backward one).
passed = !(theirPawns & passed_pawn_mask(Us, s));
- doubled = ourPawns & squares_behind(Us, s);
+ doubled = ourPawns & squares_in_front_of(Us, s);
opposed = theirPawns & squares_in_front_of(Us, s);
isolated = !(ourPawns & neighboring_files_bb(f));
chain = ourPawns & neighboring_files_bb(f) & b;
// Test for backward pawn
- //
backward = false;
- // If the pawn is passed, isolated, or member of a pawn chain
- // it cannot be backward. If can capture an enemy pawn or if
- // there are friendly pawns behind on neighboring files it cannot
- // be backward either.
+ // If the pawn is passed, isolated, or member of a pawn chain it cannot
+ // be backward. If there are friendly pawns behind on neighboring files
+ // or if can capture an enemy pawn it cannot be backward either.
if ( !(passed | isolated | chain)
- && !(ourPawns & attack_span_mask(opposite_color(Us), s))
+ && !(ourPawns & attack_span_mask(Them, s))
&& !(pos.attacks_from(s, Us) & theirPawns))
{
// We now know that there are no friendly pawns beside or behind this
@@ -200,27 +172,25 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
while (!(b & (ourPawns | theirPawns)))
Us == WHITE ? b <<= 8 : b >>= 8;
- // The friendly pawn needs to be at least two ranks closer than the enemy
- // pawn in order to help the potentially backward pawn advance.
+ // The friendly pawn needs to be at least two ranks closer than the
+ // enemy pawn in order to help the potentially backward pawn advance.
backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns;
}
- assert(passed | opposed | (attack_span_mask(Us, s) & theirPawns));
+ assert(opposed | passed | (attack_span_mask(Us, s) & theirPawns));
- // Test for candidate passed pawn
- candidate = !(opposed | passed)
- && (b = attack_span_mask(opposite_color(Us), s + pawn_push(Us)) & ourPawns) != EmptyBoardBB
+ // A not passed pawn is a candidate to become passed if it is free to
+ // advance and if the number of friendly pawns beside or behind this
+ // pawn on neighboring files is higher or equal than the number of
+ // enemy pawns in the forward direction on the neighboring files.
+ candidate = !(opposed | passed | backward | isolated)
+ && (b = attack_span_mask(Them, s + pawn_push(Us)) & ourPawns) != EmptyBoardBB
&& count_1s(b) >= count_1s(attack_span_mask(Us, s) & theirPawns);
- // In order to prevent doubled passed pawns from receiving a too big
- // bonus, only the frontmost passed pawn on each file is considered as
- // a true passed pawn.
- if (passed && (ourPawns & squares_in_front_of(Us, s)))
- passed = false;
-
- // Mark the pawn as passed. Pawn will be properly scored in evaluation
- // because we need full attack info to evaluate passed pawns.
- if (passed)
+ // Passed pawns will be properly scored in evaluation because we need
+ // full attack info to evaluate passed pawns. Only the frontmost passed
+ // pawn on each file is considered a true passed pawn.
+ if (passed && !doubled)
set_bit(&(pi->passedPawns[Us]), s);
// Score this pawn
@@ -239,6 +209,35 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
if (candidate)
value += CandidateBonus[relative_rank(Us, s)];
}
-
return value;
}
+
+
+/// PawnInfo::updateShelter() calculates and caches king shelter. It is called
+/// only when king square changes, about 20% of total king_shelter() calls.
+template
+Score PawnInfo::updateShelter(const Position& pos, Square ksq) {
+
+ const int Shift = (Us == WHITE ? 8 : -8);
+
+ Bitboard pawns;
+ int r, shelter = 0;
+
+ if (relative_rank(Us, ksq) <= RANK_4)
+ {
+ pawns = pos.pieces(PAWN, Us) & this_and_neighboring_files_bb(ksq);
+ r = ksq & (7 << 3);
+ for (int i = 0; i < 3; i++)
+ {
+ r += Shift;
+ shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (64 >> i);
+ }
+ }
+ kingSquares[Us] = ksq;
+ kingShelters[Us] = make_score(shelter, 0);
+ return kingShelters[Us];
+}
+
+// Explicit template instantiation
+template Score PawnInfo::updateShelter(const Position& pos, Square ksq);
+template Score PawnInfo::updateShelter(const Position& pos, Square ksq);