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Rearrange pawn moves generation 

Functional change due only to rearrangement

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
sf_2.3.1_base
Marco Costalba 2012-01-04 16:40:12 +01:00
parent cf247e7e30
commit 3c675db3d0
1 changed files with 81 additions and 86 deletions
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167
src/movegen.cpp
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@ -99,29 +99,29 @@ namespace {
template<Square Delta>
inline MoveStack* generate_pawn_captures(MoveStack* mlist, Bitboard pawns, Bitboard target) {
const Bitboard EdgeFileBB = ( Delta == DELTA_NE
|| Delta == DELTA_SE ? FileABB : FileHBB);
const Bitboard TFileABB = ( Delta == DELTA_NE
|| Delta == DELTA_SE ? FileABB : FileHBB);
Bitboard b;
Square to;
b = move_pawns<Delta>(pawns) & target & ~EdgeFileBB;
b = move_pawns<Delta>(pawns) & target & ~TFileABB;
SERIALIZE_MOVES_D(b, -Delta);
return mlist;
}
template<MoveType Type, Square Delta>
inline MoveStack* generate_promotions(const Position& pos, MoveStack* mlist, Bitboard pawnsOn7, Bitboard target) {
inline MoveStack* generate_promotions(MoveStack* mlist, Bitboard pawnsOn7, Bitboard target, Square ksq) {
const Bitboard EdgeFileBB = ( Delta == DELTA_NE
|| Delta == DELTA_SE ? FileABB : FileHBB);
const Bitboard TFileABB = ( Delta == DELTA_NE
|| Delta == DELTA_SE ? FileABB : FileHBB);
Bitboard b;
Square to;
b = move_pawns<Delta>(pawnsOn7) & target;
if (Delta != DELTA_N && Delta != DELTA_S)
b &= ~EdgeFileBB;
b &= ~TFileABB;
while (b)
{
@ -137,16 +137,13 @@ namespace {
(*mlist++).move = make_promotion(to - Delta, to, KNIGHT);
}
// Knight under promotion is the only one that can give a check not
// already included in the queen-promotion.
if (Type == MV_CHECK)
{
Square ksq = pos.king_square(Delta > 0 ? BLACK : WHITE);
if (bit_is_set(pos.attacks_from<KNIGHT>(to), ksq))
// Knight-promotion is the only one that can give a check (direct or
// discovered) not already included in the queen-promotion.
if ( Type == MV_CHECK
&& bit_is_set(StepAttacksBB[W_KNIGHT][to], ksq))
(*mlist++).move = make_promotion(to - Delta, to, KNIGHT);
}
else
(void)pos; // Silence a warning under MSVC
(void)ksq; // Silence a warning under MSVC
}
return mlist;
}
@ -155,32 +152,61 @@ namespace {
template<Color Us, MoveType Type>
MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard target, Square ksq) {
// Calculate our parametrized parameters at compile time, named
// according to the point of view of white side.
const Color Them = (Us == WHITE ? BLACK : WHITE);
const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
const Square UP = (Us == WHITE ? DELTA_N : DELTA_S);
const Square RIGHT_UP = (Us == WHITE ? DELTA_NE : DELTA_SW);
const Square LEFT_UP = (Us == WHITE ? DELTA_NW : DELTA_SE);
// Calculate our parametrized parameters at compile time, named according to
// the point of view of white side.
const Color Them = (Us == WHITE ? BLACK : WHITE);
const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
const Square UP = (Us == WHITE ? DELTA_N : DELTA_S);
const Square RIGHT = (Us == WHITE ? DELTA_NE : DELTA_SW);
const Square LEFT = (Us == WHITE ? DELTA_NW : DELTA_SE);
Square to;
Bitboard b1, b2, dc1, dc2, pawnPushes, emptySquares;
Bitboard pawns = pos.pieces(PAWN, Us);
Bitboard pawnsOn7 = pawns & TRank7BB;
Bitboard enemyPieces = (Type == MV_CAPTURE ? target : pos.pieces(Them));
Bitboard b1, b2, dc1, dc2, emptySquares;
// Pre-calculate pawn pushes before changing emptySquares definition
Bitboard pawns = pos.pieces(PAWN, Us);
Bitboard pawnsOn7 = pawns & TRank7BB;
Bitboard pawnsNotOn7 = pawns & ~TRank7BB;
Bitboard enemies = (Type == MV_EVASION ? pos.pieces(Them) & target:
Type == MV_CAPTURE ? target : pos.pieces(Them));
// Single and double pawn pushes, no promotions
if (Type != MV_CAPTURE)
{
emptySquares = (Type == MV_NON_CAPTURE ? target : pos.empty_squares());
pawnPushes = move_pawns<UP>(pawns & ~TRank7BB) & emptySquares;
}
if (Type == MV_EVASION)
{
emptySquares &= target; // Only blocking squares
enemyPieces &= target; // Capture only the checker piece
b1 = move_pawns<UP>(pawnsNotOn7) & emptySquares;
b2 = move_pawns<UP>(b1 & TRank3BB) & emptySquares;
if (Type == MV_EVASION)
{
b1 &= target; // Consider only blocking squares
b2 &= target;
}
if (Type == MV_CHECK)
{
// Consider only direct checks
b1 &= pos.attacks_from<PAWN>(ksq, Them);
b2 &= pos.attacks_from<PAWN>(ksq, Them);
// Add pawn pushes which give discovered check. This is possible only
// if the pawn is not on the same file as the enemy king, because we
// don't generate captures. Note that a possible discovery check
// promotion has been already generated among captures.
if (pawnsNotOn7 & target) // For CHECK type target is dc bitboard
{
dc1 = move_pawns<UP>(pawnsNotOn7 & target) & emptySquares & ~file_bb(ksq);
dc2 = move_pawns<UP>(dc1 & TRank3BB) & emptySquares;
b1 |= dc1;
b2 |= dc2;
}
}
SERIALIZE_MOVES_D(b1, -UP);
SERIALIZE_MOVES_D(b2, -UP -UP);
}
// Promotions and underpromotions
@ -189,70 +215,39 @@ namespace {
if (Type == MV_CAPTURE)
emptySquares = pos.empty_squares();
pawns &= ~TRank7BB;
mlist = generate_promotions<Type, RIGHT_UP>(pos, mlist, pawnsOn7, enemyPieces);
mlist = generate_promotions<Type, LEFT_UP>(pos, mlist, pawnsOn7, enemyPieces);
mlist = generate_promotions<Type, UP>(pos, mlist, pawnsOn7, emptySquares);
if (Type == MV_EVASION)
emptySquares &= target;
mlist = generate_promotions<Type, RIGHT>(mlist, pawnsOn7, enemies, ksq);
mlist = generate_promotions<Type, LEFT>(mlist, pawnsOn7, enemies, ksq);
mlist = generate_promotions<Type, UP>(mlist, pawnsOn7, emptySquares, ksq);
}
// Standard captures
// Standard and en-passant captures
if (Type == MV_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
{
mlist = generate_pawn_captures<RIGHT_UP>(mlist, pawns, enemyPieces);
mlist = generate_pawn_captures<LEFT_UP>(mlist, pawns, enemyPieces);
}
mlist = generate_pawn_captures<RIGHT>(mlist, pawnsNotOn7, enemies);
mlist = generate_pawn_captures<LEFT >(mlist, pawnsNotOn7, enemies);
// Single and double pawn pushes
if (Type != MV_CAPTURE)
{
b1 = (Type != MV_EVASION ? pawnPushes : pawnPushes & emptySquares);
b2 = move_pawns<UP>(pawnPushes & TRank3BB) & emptySquares;
if (Type == MV_CHECK)
if (pos.ep_square() != SQ_NONE)
{
// Consider only pawn moves which give direct checks
b1 &= pos.attacks_from<PAWN>(ksq, Them);
b2 &= pos.attacks_from<PAWN>(ksq, Them);
assert(rank_of(pos.ep_square()) == (Us == WHITE ? RANK_6 : RANK_3));
// Add pawn moves which gives discovered check. This is possible only
// if the pawn is not on the same file as the enemy king, because we
// don't generate captures.
if (pawns & target) // For CHECK type target is dc bitboard
{
dc1 = move_pawns<UP>(pawns & target & ~file_bb(ksq)) & emptySquares;
dc2 = move_pawns<UP>(dc1 & TRank3BB) & emptySquares;
// An en passant capture can be an evasion only if the checking piece
// is the double pushed pawn and so is in the target. Otherwise this
// is a discovery check and we are forced to do otherwise.
if (Type == MV_EVASION && !bit_is_set(target, pos.ep_square() - UP))
return mlist;
b1 |= dc1;
b2 |= dc2;
}
}
SERIALIZE_MOVES_D(b1, -UP);
SERIALIZE_MOVES_D(b2, -UP -UP);
}
b1 = pawnsNotOn7 & pos.attacks_from<PAWN>(pos.ep_square(), Them);
// En passant captures
if ( (Type == MV_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
&& pos.ep_square() != SQ_NONE)
{
assert(Us != WHITE || rank_of(pos.ep_square()) == RANK_6);
assert(Us != BLACK || rank_of(pos.ep_square()) == RANK_3);
assert(b1);
// An en passant capture can be an evasion only if the checking piece
// is the double pushed pawn and so is in the target. Otherwise this
// is a discovery check and we are forced to do otherwise.
if (Type == MV_EVASION && !bit_is_set(target, pos.ep_square() - UP))
return mlist;
b1 = pawns & pos.attacks_from<PAWN>(pos.ep_square(), Them);
assert(b1);
while (b1)
{
to = pop_1st_bit(&b1);
(*mlist++).move = make_enpassant(to, pos.ep_square());
while (b1)
(*mlist++).move = make_enpassant(pop_1st_bit(&b1), pos.ep_square());
}
}
return mlist;
}