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Retire Flap[] table

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Just use the equivalent Ptwist[], renamed in
MapToEdges[] to indicate that gives highest
score to pawns near the edge and then, as
second order, to bottom rank squares.
This commit is contained in:
Marco Costalba 2016-05-09 08:13:42 +02:00
parent 410fa6c74a
commit 12c3e394e7
1 changed files with 28 additions and 29 deletions
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57
src/syzygy/tbprobe.cpp
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@ -162,11 +162,10 @@ auto item(DTZPiece& e, int , int ) -> decltype(e)& { return e; }
auto item(WDLPawn& e, int stm, int f) -> decltype(e.file[stm][f])& { return e.file[stm][f]; }
auto item(DTZPawn& e, int , int f) -> decltype(e.file[f])& { return e.file[f]; }
int Flap[SQUARE_NB];
int Ptwist[SQUARE_NB];
int MapToEdges[SQUARE_NB];
int MapB1H1H7[SQUARE_NB];
int MapA1D1D4[SQUARE_NB];
int KK_idx[10][SQUARE_NB]; // [MapA1D1D4][SQUARE_NB]
int MapKK[10][SQUARE_NB]; // [MapA1D1D4][SQUARE_NB]
const uint8_t WDL_MAGIC[] = { 0x71, 0xE8, 0x23, 0x5D };
const uint8_t DTZ_MAGIC[] = { 0xD7, 0x66, 0x0C, 0xA5 };
@ -635,9 +634,9 @@ uint64_t probe_table(const Position& pos, Entry* entry, WDLScore wdl = WDLDraw,
// For pawns, TB files store separate tables according if leading pawn is on
// file a, b, c or d after reordering. To determine which of the 4 tables
// must be probed we need to extract the position's leading pawns then order
// them according to Flap table, in ascending order and finally pick the file
// of the pawn with minimum Flap[]. The new pawn order should be preserved
// because needed for next steps.
// them according to MapToEdges table, in descending order and finally
// pick the file of the pawn with maximum MapToEdges[]. The new pawn order
// should be preserved because needed for next steps.
if (entry->hasPawns) {
Piece pc = Piece(item(entry->pawn, 0, 0).precomp->pieces[0] ^ flipColor);
@ -649,8 +648,8 @@ uint64_t probe_table(const Position& pos, Entry* entry, WDLScore wdl = WDLDraw,
leadPawnsCnt = size;
auto flap = [] (Square i, Square j) { return Flap[i] < Flap[j]; };
std::sort(squares, squares + size, flap);
auto comp = [] (Square i, Square j) { return MapToEdges[i] > MapToEdges[j]; };
std::sort(squares, squares + size, comp);
tbFile = file_of(squares[0]);
if (tbFile > FILE_D)
@ -701,13 +700,13 @@ uint64_t probe_table(const Position& pos, Entry* entry, WDLScore wdl = WDLDraw,
// and encode them.
if (entry->hasPawns) {
auto ptwist = [] (Square i, Square j) { return Ptwist[i] > Ptwist[j]; };
std::sort(squares + 1, squares + leadPawnsCnt, ptwist);
auto comp = [] (Square i, Square j) { return MapToEdges[i] > MapToEdges[j]; };
std::sort(squares + 1, squares + leadPawnsCnt, comp);
idx = Pawnidx[leadPawnsCnt - 1][Flap[squares[0]]];
idx = Pawnidx[leadPawnsCnt - 1][23 - MapToEdges[squares[0]] / 2];
for (int i = 1; i < leadPawnsCnt; ++i)
idx += Binomial[i][Ptwist[squares[i]]];
idx += Binomial[i][MapToEdges[squares[i]]];
next = leadPawnsCnt;
goto encode_remaining; // With pawns we have finished special treatments
@ -793,8 +792,8 @@ uint64_t probe_table(const Position& pos, Entry* entry, WDLScore wdl = WDLDraw,
next = 3; // Continue encoding form piece[3]
} else {
// We don't have at least 3 unique pieces, like in KRRvKBB, just map
// the kings and set next to 2.
idx = KK_idx[MapA1D1D4[squares[0]]][squares[1]];
// the kings.
idx = MapKK[MapA1D1D4[squares[0]]][squares[1]];
next = 2;
}
@ -1560,34 +1559,34 @@ void Tablebases::init(const std::string& paths)
for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
{
if ((StepAttacksBB[KING][s1] | s1) & s2) // Illegal position
KK_idx[idx][s2] = -1;
MapKK[idx][s2] = -1;
else if (!off_A1H8(s1) && off_A1H8(s2) > 0)
KK_idx[idx][s2] = -1; // First king on diagonal, second above
MapKK[idx][s2] = -1; // First king on diagonal, second above
else if (!off_A1H8(s1) && !off_A1H8(s2))
bothOnDiagonal.push_back(std::make_pair(idx, s2));
else
KK_idx[idx][s2] = code++;
MapKK[idx][s2] = code++;
}
// Legal positions with both kings on diagonal are encoded as last ones
for (auto p : bothOnDiagonal)
KK_idx[p.first][p.second] = code++;
MapKK[p.first][p.second] = code++;
// Compute Flap[] that encodes (mirrored) squares a2-h7 to 0..23 and is
// used to find the file of the leading pawn. The pawn with minimum Flap[]
// is the leading pawn: this is the pawn nearest to edge and with lowest
// rank. Ptwist[] is the opposite of Flap[] and is not mirrored so squares
// are encoded to 0..46, with highest values near edge and bottom rank.
// Compute MapToEdges[] that encodes squares a2-h7 to 0..47 and is used
// to find the file of the leading pawn. The pawn with highest MapToEdges[]
// is the leading pawn: this is the pawn nearest the edge and, among pawns
// with same file, the one with lowest rank.
for (Square s = SQ_A2; s <= SQ_H7; ++s) {
Square ss = file_of(s) > FILE_D ? Square(s ^ 7) : s;
Flap[s] = 6 * file_of(ss) + rank_of(ss) - RANK_2;
Ptwist[s] = 46 + (file_of(s) <= FILE_D) - 2 * Flap[s];
}
int f = file_of(s) > FILE_D ? 12 * file_of(Square(s ^ 7)) // Flip
: 12 * file_of(s) - 1;
// Fill binomial[] with the Binomial Coefficents using Pascal triangle
MapToEdges[s] = 48 - f - 2 * rank_of(s);
}
// Fill Binomial[] with the Binomial Coefficents using Pascal triangle
Binomial[0][0] = 1;
for (int n = 1; n < 64; n++)
@ -1603,7 +1602,7 @@ void Tablebases::init(const std::string& paths)
for ( ; k < 6 * j; ++k) {
Pawnidx[i][k] = s;
s += Binomial[i][Ptwist[8 * (k % 6) + k / 6 + 8]];
s += Binomial[i][MapToEdges[8 * (k % 6) + k / 6 + 8]];
}
Pfactor[i][j - 1] = s;