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position.h

//////////////////////////////////////////////////////////////////////
//
//  FILE:       position.h
//              Position class
//
//  Part of:    Scid (Shane's Chess Information Database)
//  Version:    3.5
//
//  Notice:     Copyright (c) 1999-2003 Shane Hudson.  All rights reserved.
//
//  Author:     Shane Hudson (sgh@users.sourceforge.net)
//
//////////////////////////////////////////////////////////////////////


#ifndef SCID_POSITION_H
#define SCID_POSITION_H

#include "common.h"
#include "dstring.h"
#include "misc.h"
#include "movelist.h"
#include "sqlist.h"
#include "sqset.h"
#include "tokens.h"

//////////////////////////////////////////////////////////////////////
//  Position:  Constants

const byte  WQ_CASTLE = 1,    WK_CASTLE = 2,
            BQ_CASTLE = 4,    BK_CASTLE = 8;

// SANFlag: since checking if a move is check (to add the "+" to its
//      SAN string) takes time, and checking for mate takes even
//      longer, we specify whether we want this done with a flag.
typedef byte      sanFlagT;
const sanFlagT    SAN_NO_CHECKTEST   = 0,
                  SAN_CHECKTEST      = 1,
                  SAN_MATETEST       = 2;


// Flags that Position::PrintFEN() recognises:
//
const uint
    FEN_COMPACT = 0,
    FEN_BOARD = 1,
    FEN_CASTLING_EP = 2,
    FEN_ALL_FIELDS = 3;


// Flags that Position::GenerateMoves() recognises:
//
typedef uint genMovesT;
const genMovesT
    GEN_CAPTURES = 1,
    GEN_NON_CAPS = 2,
    GEN_ALL_MOVES = (GEN_CAPTURES | GEN_NON_CAPS);


// SANList: list of legal move strings in SAN.
//
struct sanListT
{
    bool        current;
    ushort      num;
    sanStringT  list [MAX_LEGAL_MOVES];
};


///////////////////////////////////////////////////////////////////////////
//  Position:  Class definition

class Position
{

private:
    //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    //  Position:  Data structures

    pieceT          Board[66];      // the actual board + a color square
                                    // and a NULL square.
    uint            Count[2];       // count of pieces & pawns each
    byte            Material[16];   // count of each type of piece
    byte            ListPos[64];    // ListPos stores the position in
                                        // List[][] for the piece on
                                        // square x.
    squareT         List[2][16];    // list of piece squares for each side
    byte            NumOnRank[16][8];
    byte            NumOnFyle[16][8];
    byte            NumOnLeftDiag[16][16];  // Num Queens/Bishops
    byte            NumOnRightDiag[16][16];
    byte            NumOnSquareColor[16][2];

    directionT      Pinned[16];     // For each List[ToMove][x], stores
                                        // whether piece is pinned to its
                                        // own king and dir from king.

    squareT         EPTarget;       // square pawns can EP capture to
    colorT          ToMove;
    ushort          HalfMoveClock;  // Count of halfmoves since last capture
                                    // or pawn move.
    ushort          PlyCounter;
    byte            Castling;       // castling flags
    bool            StrictCastling; // If false, allow castling after moving
                                        // the King or Rook.

    uint            Hash;           // Hash value.
    uint            PawnHash;       // Pawn structure hash value.

//    uint            NumChecks;      // Number of checks.
//    SquareList      CheckSquares;   // Stores list of pieces checking the king.

    MoveList      * LegalMoves;     // list of legal moves
    sanListT      * SANStrings;     // SAN list of legal move strs


    //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    //  Position:  Private Functions

    inline void AddHash (pieceT p, squareT sq);
    inline void UnHash (pieceT p, squareT sq);

    inline void AddToBoard (pieceT p, squareT sq);
    inline void RemoveFromBoard (pieceT p, squareT sq);

    void  CalcPinsDir (directionT dir, pieceT attacker);

    void  GenSliderMoves (MoveList * mlist, colorT c, squareT sq,
                          directionT dir, SquareSet * sqset,
                          bool capturesOnly);
    void  GenKnightMoves (MoveList * mlist, colorT c, squareT sq,
                          SquareSet * sqset, bool capturesOnly);

    void  AddLegalMove (MoveList * mlist, squareT from, squareT to, pieceT promo);
    void  GenCastling (MoveList * mlist);
    void  GenKingMoves (MoveList * mlist, genMovesT genType, bool castling);
    void  AddPromotions (MoveList * mlist, squareT from, squareT dest);
    bool  IsValidEnPassant (squareT from, squareT to);
    void  GenPawnMoves (MoveList * mlist, squareT from, directionT dir,
                        SquareSet * sqset, genMovesT genType);
    errorT      AssertPos ();   //  Checks for errors in board etc.

    //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    //  Position:  Public Functions
public:

    Position()   { Init(); }
    ~Position()  {
                     if (LegalMoves != NULL) { delete LegalMoves; }
                     if (SANStrings != NULL) { delete SANStrings; }
                  }

    void        Init();
    void        Clear();        // No pieces on board
    void        StdStart();     // Standard chess starting position
    bool        IsStdStart();
    errorT      AddPiece (pieceT p, squareT sq);

    // Set and Get attributes -- one-liners
    byte        PieceCount (pieceT p)    { return Material[p]; }
    byte *      GetMaterial ()           { return Material; }
    void        SetEPTarget (squareT s)  { EPTarget = s; }
    squareT     GetEPTarget ()           { return EPTarget; }
    bool        GetEPFlag ()             { return (EPTarget != NS); }
    void        SetToMove (colorT c)     { ToMove = c; }
    colorT      GetToMove ()             { return ToMove; }
    void        SetPlyCounter (ushort x) { PlyCounter = x; }
    ushort      GetPlyCounter ()         { return PlyCounter; }
    ushort      GetFullMoveCount ()      { return PlyCounter / 2 + 1; }
    sanListT *  GetSANStrings ()         { return SANStrings; }
    MoveList *  GetLegalMoves ()         { return LegalMoves; }

    // Methods to get the Board or piece lists -- used in game.cpp to
    // decode moves:
    squareT *   GetList (colorT c)    { return List[c]; }
    uint        GetCount (colorT c)   { return Count[c]; }
    uint        TotalMaterial ()      { return Count[WHITE] + Count[BLACK]; }
    uint        NumNonPawns (colorT c) { 
        return Count[c] - Material[piece_Make(c,PAWN)];
    }
    bool        InPawnEnding () {
        return (NumNonPawns(WHITE) == 1  &&  NumNonPawns(BLACK) == 1);
    }
    uint        MaterialValue (colorT c);
    inline uint FyleCount (pieceT p, fyleT f) {
        return NumOnFyle[p][f];
    }
    inline uint RankCount (pieceT p, rankT r) {
        return NumOnRank[p][r];
    }
    inline uint LeftDiagCount (pieceT p, leftDiagT diag) {
        return NumOnLeftDiag[p][diag];
    }
    inline uint RightDiagCount (pieceT p, rightDiagT diag) {
        return NumOnRightDiag[p][diag];
    }
    inline uint SquareColorCount (pieceT p, colorT sqColor) {
        return NumOnSquareColor[p][sqColor];
    }
    uint        GetSquares (pieceT p, SquareList * sqlist);

    pieceT *    GetBoard () {
        Board[COLOR_SQUARE] = COLOR_CHAR[ToMove];
        return Board;
    }

    // Other one-line methods
    squareT     GetKingSquare (colorT c)  { return List[c][0]; }
    squareT     GetKingSquare ()          { return List[ToMove][0]; }
    squareT     GetEnemyKingSquare ()     { return List[1-ToMove][0]; }

    // Castling flags
    inline void SetCastling (colorT c, castleDirT dir, bool flag);
    bool        GetCastling (colorT c, castleDirT dir);
    inline bool CastlingPossible () { return (Castling ? true : false); }
    byte        GetCastlingFlags () { return Castling; }
    void        SetCastlingFlags (byte b) { Castling = b; }

    void        SetStrictCastling (bool b) { StrictCastling = b; }
    bool        GetStrictCastling (void) { return StrictCastling; }

    // Allocating memory  -- maybe these should be private??
    void        AllocLegalMoves ();
    void        AllocSANStrings ();

    // Clearing data structures
    void        ClearLegalMoves ();
    void        ClearSANStrings ();

    // Hashing
    inline uint HashValue (void) { return Hash; }
    inline uint PawnHashValue (void) { return PawnHash; }
    uint        GetHPSig ();

    // Move generation and execution
    void        CalcPins();
    void        GenPieceMoves (MoveList * mlist, squareT sq,
                               SquareSet * sqset, bool capturesOnly);

    // Generate all legal moves:
    void  GenerateMoves (MoveList * mlist, pieceT mask, genMovesT genType, bool maybeInCheck);
    void  GenerateMoves () { GenerateMoves (NULL, EMPTY, GEN_ALL_MOVES, true); }
    void  GenerateMoves (MoveList * mlist) { GenerateMoves (mlist, EMPTY, GEN_ALL_MOVES, true); }
    void  GenerateMoves (MoveList * mlist, pieceT mask) { GenerateMoves (mlist, mask, GEN_ALL_MOVES, true); }
    void  GenerateMoves (MoveList * mlist, genMovesT genType) { GenerateMoves (mlist, EMPTY, genType, true); }
    void  GenerateCaptures (MoveList * mlist) { GenerateMoves (mlist, EMPTY, GEN_CAPTURES, true); }
    bool  IsLegalMove (simpleMoveT * sm);

    void        GenCheckEvasions (MoveList * mlist, pieceT mask, genMovesT genType, SquareList * checkSquares);
    void        MatchLegalMove (MoveList * mlist, pieceT mask, squareT target);
    errorT      MatchPawnMove (MoveList * mlist, fyleT fromFyle, squareT to, pieceT promote);
    errorT      MatchKingMove (MoveList * mlist, squareT target);

    uint        CalcAttacks (colorT toMove, squareT kingSq, SquareList * squares);
    uint        CalcNumChecks () {
                    return CalcAttacks (1-ToMove, GetKingSquare(), NULL);
                }
    uint        CalcNumChecks (squareT kingSq) {
                    return CalcAttacks (1-ToMove, kingSq, NULL);
                }
    uint        CalcNumChecks (squareT kingSq, SquareList * checkSquares) {
                    return CalcAttacks (1-ToMove, kingSq, checkSquares);
                }

    uint        Mobility (pieceT p, colorT color, squareT from);
    pieceT      SmallestDefender (colorT color, squareT target);
    bool        IsKingInCheck () { return (CalcNumChecks() > 0); }
    bool        IsKingInCheckDir (directionT dir);
    bool        IsKingInCheck (simpleMoveT * sm);
    bool        IsKingInMate ();
    bool        IsLegal ();

    bool        IsPromoMove (squareT from, squareT to);

    void        DoSimpleMove (simpleMoveT * sm);    // move execution ...
    void        UndoSimpleMove (simpleMoveT * sm);  // ... and taking back

    errorT      RelocatePiece (squareT fromSq, squareT toSq);

    void        MakeSANString (simpleMoveT * sm, char * s, sanFlagT flag);
    void        CalcSANStrings (sanFlagT flag);

    errorT      ReadCoordMove (simpleMoveT * m, const char * s, bool reverse);
    errorT      ReadMove (simpleMoveT * m, const char * s, tokenT t);
    errorT      ParseMove (simpleMoveT * sm, const char * s);
    errorT      ReadLine (const char * s);

    // Board I/O
    void        MakeLongStr (char * str);
    void        DumpBoard (FILE * fp);
    void        DumpLists (FILE * fp);
    errorT      ReadFromLongStr (const char * str);
    errorT      ReadFromCompactStr (const byte * str);
    errorT      ReadFromFEN (const char * s);
    void        PrintCompactStr (char * cboard);
    void        PrintCompactStrFlipped (char * cboard);
    byte        CompactStrFirstByte () {
        return (Board[0] << 4) | Board[1];
    }
    void        PrintFEN (char * str, uint flags);
    void        DumpLatexBoard (DString * dstr, bool flip);
    void        DumpLatexBoard (DString * dstr) {
        DumpLatexBoard (dstr, false);
    }
    void        DumpHtmlBoard (DString * dstr, uint style, const char * dir,
                               bool flip);
    void        DumpHtmlBoard (DString * dstr, uint style, const char * dir) {
        DumpHtmlBoard (dstr, style, dir, false);
    }

    // Copy, compare positions
    int         Compare (Position * p);
    void        CopyFrom (Position * src);

    // Set up a random position:
    errorT      Random (const char * material);
};



//////////////////////////////////////////////////////////////////////
//  Position:  Public Inline Functions


//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Position::SetCastling():
//      Set a castling flag.
//
inline void
Position::SetCastling (colorT c, castleDirT dir, bool flag)
{
    register byte b = (c==WHITE ? 1 : 4);
    if (dir == KSIDE) b += b;
    // Now b = 1 or 2 (white flags), or 4 or 8 (black flags)
    if (flag) { Castling |= b; } else { Castling &= (255-b); }
    return;
}

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Position::GetCastling():
//      Get a castling flag.
//
inline bool
Position::GetCastling (colorT c, castleDirT dir)
{
    register byte b = (c==WHITE ? 1 : 4);
    if (dir == KSIDE) b += b;
    // Now b == 1 or 2 (white flags), or 4 or 8 (black flags)
    if (Castling & b) { return true; } else { return false; }
}

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Position::AllocLegalMoves():
//      Allocate the legal moves list.
//
inline void
Position::AllocLegalMoves ()
{
    ASSERT (LegalMoves == NULL);
    LegalMoves = new MoveList();
}

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Position::AllocSANStrings():
//      Allocate the SAN strings list.
//
inline void
Position::AllocSANStrings ()
{
    ASSERT (SANStrings == NULL);
    SANStrings = new sanListT;
    SANStrings->current = false;
}

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Position::ClearLegalMoves():
//      Reset the legal moves list.
//
inline void
Position::ClearLegalMoves ()
{
    if (LegalMoves == NULL) { AllocLegalMoves(); }
    LegalMoves->Clear();
}

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Position::ClearSANStrings():
//      Reset the SAN moves list.
//
inline void
Position::ClearSANStrings ()
{
    if (SANStrings) { SANStrings->current = false; }
    else            { AllocSANStrings(); }
}

#endif  // SCID_POSITION_H

//////////////////////////////////////////////////////////////////////
//  EOF: position.h
//////////////////////////////////////////////////////////////////////


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