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Better naming in endgame code 

And small clean-up of magic bitboards code.

No functional change.

Closes #1138
pull/1139/merge
Marco Costalba 2017-06-04 11:03:23 +02:00 committed by Joona Kiiski
parent f907d5b7d9
commit 27ba611a3d
8 changed files with 75 additions and 92 deletions
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2
src/Makefile
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@ -452,7 +452,7 @@ install:
#clean all
clean: objclean profileclean
@rm -f .depend *~ core
@rm -f .depend *~ core
# clean binaries and objects
objclean:

61
src/bitboard.cpp
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@ -26,9 +26,6 @@
uint8_t PopCnt16[1 << 16];
int SquareDistance[SQUARE_NB][SQUARE_NB];
Magic RookMagics[SQUARE_NB];
Magic BishopMagics[SQUARE_NB];
Bitboard SquareBB[SQUARE_NB];
Bitboard FileBB[FILE_NB];
Bitboard RankBB[RANK_NB];
@ -43,6 +40,9 @@ Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB];
Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
Magic RookMagics[SQUARE_NB];
Magic BishopMagics[SQUARE_NB];
namespace {
// De Bruijn sequences. See chessprogramming.wikispaces.com/BitScan
@ -54,7 +54,7 @@ namespace {
Bitboard RookTable[0x19000]; // To store rook attacks
Bitboard BishopTable[0x1480]; // To store bishop attacks
typedef unsigned (Fn)(Square, Bitboard);
typedef unsigned (Fn)(const Magic&, Bitboard);
void init_magics(Bitboard table[], Magic magics[], Square deltas[], Fn index);
@ -204,8 +204,8 @@ void Bitboards::init() {
Square RookDeltas[] = { NORTH, EAST, SOUTH, WEST };
Square BishopDeltas[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST };
init_magics(RookTable, RookMagics, RookDeltas, magic_index<ROOK>);
init_magics(BishopTable, BishopMagics, BishopDeltas, magic_index<BISHOP>);
init_magics(RookTable, RookMagics, RookDeltas, magic_index);
init_magics(BishopTable, BishopMagics, BishopDeltas, magic_index);
for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
{
@ -257,10 +257,7 @@ namespace {
{ 728, 10316, 55013, 32803, 12281, 15100, 16645, 255 } };
Bitboard occupancy[4096], reference[4096], edges, b;
int age[4096] = {0}, current = 0, i, size;
// attacks[s] is a pointer to the beginning of the attacks table for square 's'
magics[SQ_A1].attacks = table;
int epoch[4096] = {}, cnt = 0, size = 0;
for (Square s = SQ_A1; s <= SQ_H8; ++s)
{
@ -272,8 +269,13 @@ namespace {
// all the attacks for each possible subset of the mask and so is 2 power
// the number of 1s of the mask. Hence we deduce the size of the shift to
// apply to the 64 or 32 bits word to get the index.
magics[s].mask = sliding_attack(deltas, s, 0) & ~edges;
magics[s].shift = (Is64Bit ? 64 : 32) - popcount(magics[s].mask);
Magic& m = magics[s];
m.mask = sliding_attack(deltas, s, 0) & ~edges;
m.shift = (Is64Bit ? 64 : 32) - popcount(m.mask);
// Set the offset for the attacks table of the square. We have individual
// table sizes for each square with "Fancy Magic Bitboards".
m.attacks = s == SQ_A1 ? table : magics[s - 1].attacks + size;
// Use Carry-Rippler trick to enumerate all subsets of masks[s] and
// store the corresponding sliding attack bitboard in reference[].
@ -283,17 +285,12 @@ namespace {
reference[size] = sliding_attack(deltas, s, b);
if (HasPext)
magics[s].attacks[pext(b, magics[s].mask)] = reference[size];
m.attacks[pext(b, m.mask)] = reference[size];
size++;
b = (b - magics[s].mask) & magics[s].mask;
b = (b - m.mask) & m.mask;
} while (b);
// Set the offset for the table of the next square. We have individual
// table sizes for each square with "Fancy Magic Bitboards".
if (s < SQ_H8)
magics[s + 1].attacks = magics[s].attacks + size;
if (HasPext)
continue;
@ -301,28 +298,30 @@ namespace {
// Find a magic for square 's' picking up an (almost) random number
// until we find the one that passes the verification test.
do {
do
magics[s].magic = rng.sparse_rand<Bitboard>();
while (popcount((magics[s].magic * magics[s].mask) >> 56) < 6);
for (int i = 0; i < size; )
{
for (m.magic = 0; popcount((m.magic * m.mask) >> 56) < 6; )
m.magic = rng.sparse_rand<Bitboard>();
// A good magic must map every possible occupancy to an index that
// looks up the correct sliding attack in the attacks[s] database.
// Note that we build up the database for square 's' as a side
// effect of verifying the magic.
for (++current, i = 0; i < size; ++i)
// effect of verifying the magic. Keep track of the attempt count
// and save it in epoch[], little speed-up trick to avoid resetting
// m.attacks[] after every failed attempt.
for (++cnt, i = 0; i < size; ++i)
{
unsigned idx = index(s, occupancy[i]);
unsigned idx = index(m, occupancy[i]);
if (age[idx] < current)
if (epoch[idx] < cnt)
{
age[idx] = current;
magics[s].attacks[idx] = reference[i];
epoch[idx] = cnt;
m.attacks[idx] = reference[i];
}
else if (magics[s].attacks[idx] != reference[i])
else if (m.attacks[idx] != reference[i])
break;
}
} while (i < size);
}
}
}
}

48
src/bitboard.h
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@ -76,6 +76,18 @@ extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
extern Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
/// Magic holds all magic bitboards relevant data for a single square
struct Magic {
Bitboard mask;
Bitboard magic;
Bitboard* attacks;
unsigned shift;
};
extern Magic RookMagics[SQUARE_NB];
extern Magic BishopMagics[SQUARE_NB];
/// Overloads of bitwise operators between a Bitboard and a Square for testing
/// whether a given bit is set in a bitboard, and for setting and clearing bits.
@ -209,47 +221,27 @@ template<> inline int distance<File>(Square x, Square y) { return distance(file_
template<> inline int distance<Rank>(Square x, Square y) { return distance(rank_of(x), rank_of(y)); }
/// Magic holds all magic relevant data for a single square
struct Magic {
Bitboard mask;
Bitboard magic;
Bitboard* attacks;
unsigned shift;
};
/// attacks_bb() returns a bitboard representing all the squares attacked by a
/// piece of type Pt (bishop or rook) placed on 's'. The helper magic_index()
/// looks up the index using the 'magic bitboards' approach.
template<PieceType Pt>
inline unsigned magic_index(Square s, Bitboard occupied) {
extern Magic RookMagics[SQUARE_NB];
extern Magic BishopMagics[SQUARE_NB];
const Magic* Magics = Pt == ROOK ? RookMagics : BishopMagics;
Bitboard mask = Magics[s].mask;
Bitboard magic = Magics[s].magic;
unsigned shift = Magics[s].shift;
inline unsigned magic_index(const Magic& m, Bitboard occupied) {
if (HasPext)
return unsigned(pext(occupied, mask));
return unsigned(pext(occupied, m.mask));
if (Is64Bit)
return unsigned(((occupied & mask) * magic) >> shift);
return unsigned(((occupied & m.mask) * m.magic) >> m.shift);
unsigned lo = unsigned(occupied) & unsigned(mask);
unsigned hi = unsigned(occupied >> 32) & unsigned(mask >> 32);
return (lo * unsigned(magic) ^ hi * unsigned(magic >> 32)) >> shift;
unsigned lo = unsigned(occupied) & unsigned(m.mask);
unsigned hi = unsigned(occupied >> 32) & unsigned(m.mask >> 32);
return (lo * unsigned(m.magic) ^ hi * unsigned(m.magic >> 32)) >> m.shift;
}
template<PieceType Pt>
inline Bitboard attacks_bb(Square s, Bitboard occupied) {
extern Magic RookMagics[SQUARE_NB];
extern Magic BishopMagics[SQUARE_NB];
return (Pt == ROOK ? RookMagics : BishopMagics)[s].attacks[magic_index<Pt>(s, occupied)];
const Magic& M = Pt == ROOK ? RookMagics[s] : BishopMagics[s];
return M.attacks[magic_index(M, occupied)];
}
inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) {

8
src/endgame.cpp
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@ -110,14 +110,6 @@ Endgames::Endgames() {
}
template<EndgameType E, typename T>
void Endgames::add(const string& code) {
StateInfo st;
map<T>()[Position().set(code, WHITE, &st).material_key()] = std::unique_ptr<EndgameBase<T>>(new Endgame<E>(WHITE));
map<T>()[Position().set(code, BLACK, &st).material_key()] = std::unique_ptr<EndgameBase<T>>(new Endgame<E>(BLACK));
}
/// Mate with KX vs K. This function is used to evaluate positions with
/// king and plenty of material vs a lone king. It simply gives the
/// attacking side a bonus for driving the defending king towards the edge

40
src/endgame.h
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@ -31,12 +31,11 @@
#include "types.h"
/// EndgameType lists all supported endgames
/// EndgameCode lists all supported endgame functions by corresponding codes
enum EndgameType {
// Evaluation functions
enum EndgameCode {
EVALUATION_FUNCTIONS,
KNNK, // KNN vs K
KXK, // Generic "mate lone king" eval
KBNK, // KBN vs K
@ -47,10 +46,7 @@ enum EndgameType {
KQKP, // KQ vs KP
KQKR, // KQ vs KR
// Scaling functions
SCALING_FUNCTIONS,
KBPsK, // KB and pawns vs K
KQKRPs, // KQ vs KR and pawns
KRPKR, // KRP vs KR
@ -68,30 +64,28 @@ enum EndgameType {
/// Endgame functions can be of two types depending on whether they return a
/// Value or a ScaleFactor.
template<EndgameType E> using
template<EndgameCode E> using
eg_type = typename std::conditional<(E < SCALING_FUNCTIONS), Value, ScaleFactor>::type;
/// Base and derived templates for endgame evaluation and scaling functions
/// Base and derived functors for endgame evaluation and scaling functions
template<typename T>
struct EndgameBase {
explicit EndgameBase(Color c) : strongSide(c), weakSide(~c) {}
virtual ~EndgameBase() = default;
virtual Color strong_side() const = 0;
virtual T operator()(const Position&) const = 0;
const Color strongSide, weakSide;
};
template<EndgameType E, typename T = eg_type<E>>
template<EndgameCode E, typename T = eg_type<E>>
struct Endgame : public EndgameBase<T> {
explicit Endgame(Color c) : strongSide(c), weakSide(~c) {}
Color strong_side() const { return strongSide; }
explicit Endgame(Color c) : EndgameBase<T>(c) {}
T operator()(const Position&) const;
private:
Color strongSide, weakSide;
};
@ -101,16 +95,22 @@ private:
class Endgames {
template<typename T> using Map = std::map<Key, std::unique_ptr<EndgameBase<T>>>;
template<EndgameType E, typename T = eg_type<E>>
void add(const std::string& code);
template<typename T> using Ptr = std::unique_ptr<EndgameBase<T>>;
template<typename T> using Map = std::map<Key, Ptr<T>>;
template<typename T>
Map<T>& map() {
return std::get<std::is_same<T, ScaleFactor>::value>(maps);
}
template<EndgameCode E, typename T = eg_type<E>, typename P = Ptr<T>>
void add(const std::string& code) {
StateInfo st;
map<T>()[Position().set(code, WHITE, &st).material_key()] = P(new Endgame<E>(WHITE));
map<T>()[Position().set(code, BLACK, &st).material_key()] = P(new Endgame<E>(BLACK));
}
std::pair<Map<Value>, Map<ScaleFactor>> maps;
public:

2
src/material.cpp
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@ -155,7 +155,7 @@ Entry* probe(const Position& pos) {
if ((sf = pos.this_thread()->endgames.probe<ScaleFactor>(key)) != nullptr)
{
e->scalingFunction[sf->strong_side()] = sf; // Only strong color assigned
e->scalingFunction[sf->strongSide] = sf; // Only strong color assigned
return e;
}

2
src/search.cpp
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@ -335,7 +335,7 @@ void Thread::search() {
MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr);
std::memset(ss-4, 0, 7 * sizeof(Stack));
for(int i = 4; i > 0; i--)
for (int i = 4; i > 0; i--)
(ss-i)->history = &this->counterMoveHistory[NO_PIECE][0]; // Use as sentinel
bestValue = delta = alpha = -VALUE_INFINITE;

4
src/syzygy/tbprobe.cpp
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@ -531,14 +531,14 @@ int decompress_pairs(PairsData* d, uint64_t idx) {
//
// I(k) = k * d->span + d->span / 2 (1)
// First step is to get the 'k' of the I(k) nearest to our idx, using defintion (1)
// First step is to get the 'k' of the I(k) nearest to our idx, using definition (1)
uint32_t k = idx / d->span;
// Then we read the corresponding SparseIndex[] entry
uint32_t block = number<uint32_t, LittleEndian>(&d->sparseIndex[k].block);
int offset = number<uint16_t, LittleEndian>(&d->sparseIndex[k].offset);
// Now compute the difference idx - I(k). From defintion of k we know that
// Now compute the difference idx - I(k). From definition of k we know that
//
// idx = k * d->span + idx % d->span (2)
//