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Small rewrite of backward pawn test

Browse source 
No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-07-19 07:13:50 +01:00
parent b5178597bd
commit 95388a952b
1 changed files with 6 additions and 6 deletions
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12
src/pawns.cpp
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@ -214,7 +214,7 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
pi->qsStormValue[Us] += QStormTable[relative_square(Us, s)] + bonus; pi->qsStormValue[Us] += QStormTable[relative_square(Us, s)] + bonus;
// Our rank plus previous one. Used for chain detection. // Our rank plus previous one. Used for chain detection.
b = rank_bb(r) | rank_bb(r + (Us == WHITE ? -1 : 1)); b = rank_bb(r) | rank_bb(Us == WHITE ? r - 1 : r + 1);
// Passed, isolated, doubled or member of a pawn // Passed, isolated, doubled or member of a pawn
// chain (but not the backward one) ? // chain (but not the backward one) ?
@ -226,15 +226,15 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
// Test for backward pawn // Test for backward pawn
// //
backward = false;
// If the pawn is passed, isolated, or member of a pawn chain // If the pawn is passed, isolated, or member of a pawn chain
// it cannot be backward. If can capture an enemy pawn or if // it cannot be backward. If can capture an enemy pawn or if
// there are friendly pawns behind on neighboring files it cannot // there are friendly pawns behind on neighboring files it cannot
// be backward either. // be backward either.
if ( (passed | isolated | chain) if ( !(passed | isolated | chain)
|| (ourPawns & attack_span_mask(opposite_color(Us), s)) && !(ourPawns & attack_span_mask(opposite_color(Us), s))
|| (pos.attacks_from<PAWN>(s, Us) & theirPawns)) && !(pos.attacks_from<PAWN>(s, Us) & theirPawns))
backward = false;
else
{ {
// We now know that there are no friendly pawns beside or behind this // We now know that there are no friendly pawns beside or behind this
// pawn on neighboring files. We now check whether the pawn is // pawn on neighboring files. We now check whether the pawn is