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Bench 3110425
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@MJZ1977
MJZ1977 committed May 13, 2019
1 parent 7f1fd7c commit 02092ac
Showing 1 changed file with 11 additions and 6 deletions.
17 changes: 11 additions & 6 deletions src/pawns.cpp
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Expand Up @@ -69,7 +69,7 @@ namespace {

Bitboard b, neighbours, stoppers, doubled, support, phalanx;
Bitboard lever, leverPush;
Square s;
Square s, opposedPawn;
bool opposed, backward;
Score score = SCORE_ZERO;
const Square* pl = pos.squares<PAWN>(Us);
Expand All @@ -89,11 +89,6 @@ namespace {
File f = file_of(s);
Rank r = relative_rank(Us, s);

if (theirPawns & (s+Up))
e->pawnAttacksSpan[Us] |= PawnAttacks[Us][s];
else
e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);

// Flag the pawn
opposed = theirPawns & forward_file_bb(Us, s);
stoppers = theirPawns & passed_pawn_span(Us, s);
Expand All @@ -104,6 +99,16 @@ namespace {
phalanx = neighbours & rank_bb(s);
support = neighbours & rank_bb(s - Up);

if (Us == WHITE)
opposedPawn = lsb(theirPawns & forward_file_bb(Us, s));
else
opposedPawn = msb(theirPawns & forward_file_bb(Us, s));

if (opposed)
e->pawnAttacksSpan[Us] |= (pawn_attack_span(Us, s) & ~pawn_attack_span(Us, opposedPawn));
else
e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);

// A pawn is backward when it is behind all pawns of the same color
// on the adjacent files and cannot be safely advanced.
backward = !(ourPawns & pawn_attack_span(Them, s + Up))
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2 comments on commit 02092ac

@locutus2
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@MJZ1977
This patch have the problem that the lsb and msb functions are not well defined if the argument is zero (which is the case if the pawn unopposed).

Also its better to use the function backmost_sq instead of lsb and msb. This is more readable and hides the use of lsb and msb.

So following code would be correct and more readable:
if (opposed) e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s) & ~pawn_attack_span(Us, backmost_sq(Us, theirPawns & forward_file_bb(Us, s))); else e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);

@MJZ1977
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Thank you for advice !

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