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Init MapToEdges[] with other tables

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And simplify LeadPawnIdx[] usage.
This commit is contained in:
Marco Costalba 2016-05-16 12:58:54 +02:00
parent 1cbaaaef68
commit f5ac865866
1 changed files with 25 additions and 27 deletions
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52
src/syzygy/tbprobe.cpp
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@ -218,9 +218,9 @@ std::string TBPaths;
std::deque<WDLEntry> WDLTable;
std::list<DTZEntry> DTZTable;
int Binomial[6][64]; // [k][n] k elements from a set of n elements
int LeadPawnIdx[4][24]; // [leadPawnsCnt - 1][MapToEdges[Sq]]
int LeadPawnsGroupSize[4][4]; // [leadPawnsCnt - 1][FILE_A..FILE_D]
int Binomial[6][SQUARE_NB]; // [k][n] k elements from a set of n elements
int LeadPawnIdx[4][SQUARE_NB]; // [leadPawnsCnt - 1][SQUARE_NB]
int LeadPawnsGroupSize[4][4]; // [leadPawnsCnt - 1][FILE_A..FILE_D]
enum { BigEndian, LittleEndian };
@ -767,7 +767,7 @@ uint64_t probe_table(const Position& pos, Entry* entry, WDLScore wdl = WDLDraw,
// Encode leading pawns. Note that any previous horizontal flip preserves
// the order because MapToEdges[] is (almost) flip invariant.
if (entry->hasPawns) {
idx = LeadPawnIdx[leadPawnsCnt - 1][23 - MapToEdges[squares[0]] / 2];
idx = LeadPawnIdx[leadPawnsCnt - 1][squares[0]];
for (int i = 1; i < leadPawnsCnt; ++i)
idx += Binomial[i][MapToEdges[squares[leadPawnsCnt- i]]];
@ -1574,17 +1574,6 @@ void Tablebases::init(const std::string& paths)
for (auto p : bothOnDiagonal)
MapKK[p.first][p.second] = code++;
// 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) {
int f = file_of(s) > FILE_D ? 12 * file_of(Square(s ^ 7)) // Flip
: 12 * file_of(s) - 1;
MapToEdges[s] = 48 - f - 2 * rank_of(s);
}
// Fill Binomial[] with the Binomial Coefficents using Pascal rule. There
// are Binomial[k][n] ways to choose k elements from a set of n elements.
Binomial[0][0] = 1;
@ -1594,12 +1583,15 @@ void Tablebases::init(const std::string& paths)
Binomial[k][n] = (k > 0 ? Binomial[k - 1][n - 1] : 0)
+ (k < n ? Binomial[k ][n - 1] : 0);
// Init tables for the encoding of leading pawns group: with 6-men TB we
// MapToEdges[s] encodes squares a2-h7 to 0..47. It is the number of possible
// available squares when the leading one is in 's'. Moreover the pawn with
// highest MapToEdges[] is the leading pawn, the one nearest the edge and,
// among pawns with same file, the one with lowest rank.
int availableSquares = 47; // Available squares when lead pawn is in a2
// Init the tables for the encoding of leading pawns group: with 6-men TB we
// can have up to 4 leading pawns (KPPPPK).
for (int leadPawnsCnt = 1; leadPawnsCnt <= 4; ++leadPawnsCnt)
{
int mappedLeadSq = 0; // From a2 to d7 (a2a7...d2d7) mapped to 0..23
for (File f = FILE_A; f <= FILE_D; ++f)
{
// Restart the index at every file because TB table is splitted
@ -1608,20 +1600,26 @@ void Tablebases::init(const std::string& paths)
// Sum all possible combinations for a given file, starting with
// the leading pawn on rank 2 and increasing the rank.
for (Rank r = RANK_2; r <= RANK_7; ++r, ++mappedLeadSq)
for (Rank r = RANK_2; r <= RANK_7; ++r)
{
LeadPawnIdx[leadPawnsCnt - 1][mappedLeadSq] = idx;
Square sq = make_square(f, r);
// Given the leadSq any other pawn cannot be below or more
// toward the edge of leadSq. Start with 47 available squares
// when lead pawn is in a2 and after an increase the number is
// reduced by two due to mirroring, e.g. a3 -> no a2, h2
idx += Binomial[leadPawnsCnt - 1][47 - 2 * mappedLeadSq];
// Compute MapToEdges[] at first pass.
// If sq is the leading pawn square, any other pawn cannot be
// below or more toward the edge of sq. There are 47 available
// squares when sq = a2 and reduced by 2 for any rank increase
// due to mirroring: sq == a3 -> no a2, h2, so MapToEdges[a3] = 45
if (leadPawnsCnt == 1)
{
MapToEdges[sq] = availableSquares--;
MapToEdges[sq ^ 7] = availableSquares--; // Horizontal flip
}
LeadPawnIdx[leadPawnsCnt - 1][sq] = idx;
idx += Binomial[leadPawnsCnt - 1][MapToEdges[sq]];
}
// After a file is traversed, store the cumulated per-file index
LeadPawnsGroupSize[leadPawnsCnt - 1][f] = idx;
}
}
for (PieceType p1 = PAWN; p1 < KING; ++p1) {
WDLHash.insert({KING, p1, KING});