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Unify History and Gains under a single Stats class

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Handling of History and Gains is almost the same, with
the exception of the update logic, so unify both
classes under a single Stats struct.

No functional change.
This commit is contained in:
Marco Costalba
2013-02-02 17:13:33 +01:00
parent 53051eefc7
commit ddbe6082c4
4 changed files with 46 additions and 51 deletions
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45
src/movepick.h
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@@ -20,35 +20,46 @@
#if !defined MOVEPICK_H_INCLUDED
#define MOVEPICK_H_INCLUDED
#include <algorithm> // For std::max
#include <cstring> // For memset
#include "position.h"
#include "search.h"
#include "types.h"
/// The History class stores statistics about how often different moves
/// have been successful or unsuccessful during the current search. These
/// statistics are used for reduction and move ordering decisions. History
/// entries are stored according only to moving piece and destination square,
/// in particular two moves with different origin but same destination and
/// same piece will be considered identical.
class History {
public:
/// The Stats struct stores moves statistics. According to the template parameter
/// the class can store both History and Gains type statistics. History records
/// how often different moves have been successful or unsuccessful during the
/// current search and is used for reduction and move ordering decisions. Gains
/// records the move's best evaluation gain from one ply to the next and is used
/// for pruning decisions. Entries are stored according only to moving piece and
/// destination square, in particular two moves with different origin but same
/// destination and same piece will be considered identical.
template<bool Gain>
struct Stats {
static const Value Max = Value(2000);
const Value* operator[](Piece p) const { return &history[p][0]; }
Value gain(Piece p, Square to) const { return gains[p][to]; }
const Value* operator[](Piece p) const { return &table[p][0]; }
void clear() { memset(table, 0, sizeof(table)); }
void clear();
void update(Piece p, Square to, Value bonus);
void update_gain(Piece p, Square to, Value gain);
void update(Piece p, Square to, Value v) {
if (Gain)
table[p][to] = std::max(v, table[p][to] - 1);
else if (abs(table[p][to] + v) < Max)
table[p][to] += v;
}
private:
Value history[PIECE_NB][SQUARE_NB];
Value gains[PIECE_NB][SQUARE_NB];
Value table[PIECE_NB][SQUARE_NB];
};
typedef Stats<false> History;
typedef Stats<true> Gains;
/// MovePicker class is used to pick one pseudo legal move at a time from the
/// current position. The most important method is next_move(), which returns a
@@ -74,7 +85,7 @@ private:
void generate_next();
const Position& pos;
const History& H;
const History& Hist;
Search::Stack* ss;
Depth depth;
Move ttMove;