//////////////////////////////////////////////////////////////////////
//
//  FILE:       common.h
//              Common macros, structures and constants.
//
//  Part of:    Scid (Shane's Chess Information Database)
//  Version:    3.6.6
//
//  Notice:     Copyright (c) 2000-2004  Shane Hudson.  All rights reserved.
//
//  Author:     Shane Hudson (sgh@users.sourceforge.net)
//              Copyright (c) 2006-2007 Pascal Georges
//
//////////////////////////////////////////////////////////////////////

#ifndef SCID_COMMON_H
#define SCID_COMMON_H

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// HEADER FILES:

#include <stdio.h>
#include <stdlib.h>
#include "myassert.h"
#include "error.h"

/* Windows _snprintf does not null terminate, so we don't use snprintf
#ifdef _MSC_VER
#define snprintf _snprintf
#endif
*/

// Include the zlib header file if it is being compiled with Scid:
#ifndef NO_ZLIB
#  ifdef ZLIB
#    include "zlib/zlib.h"
#   else
#    include <zlib.h>
#  endif
#endif
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CONSTANTS:

// Buffer sizes
#define BBUF_SIZE 256000 //120000
#define TBUF_SIZE 1280000 //160000

typedef unsigned short versionT;

// Version: div by 100 for major number, modulo 100 for minor number
// so 109 = 1.9, 110 = 1.10, etc.

const versionT SCID_VERSION = 400;        // Current file format version = 4.0
const versionT SCID_OLDEST_VERSION = 400; // Oldest compatible format: 4.0

const char SCID_VERSION_STRING[] = "4.27";     // Current version
const char SCID_VERSION_DATE[] = "May 20, 2026";
const char SCID_WEBSITE[] = "http://scidvspc.sourceforge.net/";

const char TREEFILE_SUFFIX[] = ".stc";
const char GZIP_SUFFIX[] = ".gz";
const char ZIP_SUFFIX[] = ".zip";
const char PGN_SUFFIX[] = ".pgn";


// If the zlib compression library is NOT used, create dummy inline
// functions to replace those used in zlib, which saves wrapping every
// zlib function call with #ifndef conditions.

#ifdef NO_ZLIB
typedef void * gzFile;
inline gzFile gzopen (const char * name, const char * mode) { return NULL; }
inline int gzputc (gzFile fp, int c) { return c; }
inline int gzgetc (gzFile fp) { return -1; }
inline int gzread (gzFile fp, char * buffer, int length) { return 0; }
inline int gzeof (gzFile fp) { return 1; }
inline int gzseek (gzFile fp, int offset, int where) { return 0; }
inline int gzclose (gzFile fp) { return 0; }
#endif


// Bit Manipulations

#define BIT_7(x)            ((x) & 128)
#define BIT_6(x)            ((x) &  64)
#define BIT_5(x)            ((x) &  32)
#define BIT_4(x)            ((x) &  16)
#define BIT_3(x)            ((x) &   8)
#define BIT_2(x)            ((x) &   4)
#define BIT_1(x)            ((x) &   2)
#define BIT_0(x)            ((x) &   1)

// Upper or lower 4 bits of a byte, in the range 0..15

#define UPPER_4_BITS(x)     (((x) & 240) >> 4)      // 240 is (15 * 16)
#define LOWER_4_BITS(x)     ((x) &  15)

//  Upper or lower 12 bits of an integer, in the range 0..4095
//
#define UPPER_12_BITS(x)    (((x) & (4096 * 4095)) >> 12)
#define LOWER_12_BITS(x)    ((x) &  4095)


//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// TYPE DEFINITIONS

//  General types

typedef unsigned char           byte;           //  8 bit unsigned
typedef unsigned short          ushort;         // 16 bit unsigned
typedef unsigned int            uint;           // 32 bit unsigned
typedef signed   int            sint;           // 32 bit signed
typedef unsigned long           ulong;


//  compareT: comparison type

typedef signed int    compareT;
const compareT
    LESS_THAN = -1,   EQUAL_TO = 0,   GREATER_THAN = 1;

//  Chess Types

typedef byte                    pieceT;      // e.g ROOK or WK
typedef byte                    colorT;      // WHITE or BLACK
typedef byte                    squareT;     // e.g. A3
typedef byte                    directionT;  // e.g. UP_LEFT
typedef byte                    rankT;       // Chess board rank
typedef byte                    fyleT;       // Chess board file
typedef byte                    leftDiagT;   // Up-left diagonals
typedef byte                    rightDiagT;  // Up-right diagonals

// boardT: 64 squares plus two extra squares: one for storing the side
//   to move as a byte and one for the string terminator, so boards can
//   be compared using regular string functions:
typedef pieceT                  boardT [66];

typedef byte                    smallBoardT [32];
                                    // A more densely packed board, 2 squares
                                    // per byte.

typedef byte                    castleDirT;  // LEFT or RIGHT

//  Other Small Types

typedef ushort                  statusT;

//  Fixed String Types

typedef char    sanStringT [ 10];   // SAN Move Notation

//  File-related Types

typedef char    fileNameT [512];
typedef uint    fileLengthT;

enum fileModeT {
    FMODE_None = 0,
    FMODE_ReadOnly,
    FMODE_WriteOnly,
    FMODE_Both
};

//  Date type: see date.h and date.cpp

typedef uint    dateT;

//  Game Information types

typedef uint            gameNumberT;      // Used in Index class
typedef ushort          eloT;
typedef ushort          ecoT;
typedef char            ecoStringT [6];   /* "A00j1" */

const ecoT ECO_None = 0;

// Rating types:

const byte RATING_Elo = 0;
const byte RATING_Rating = 1;
const byte RATING_Rapid = 2;
const byte RATING_ICCF = 3;
const byte RATING_USCF = 4;
const byte RATING_DWZ = 5;
const byte RATING_BCF = 6;

extern const char * ratingTypeNames [17];   // Defined in game.cpp


// NameBase types: see namebase.h and namebase.cpp

typedef uint            idNumberT;
typedef uint            nameT;

// Result Type

const uint NUM_RESULT_TYPES = 4;
typedef byte    resultT;
const resultT
    RESULT_None  = 0,
    RESULT_White = 1,
    RESULT_Black = 2,
    RESULT_Draw  = 3;

const uint RESULT_SCORE[4] = { 1, 2, 0, 1 };

const char RESULT_CHAR [4]       = { '*',  '1',    '0',    '='       };
const char RESULT_STR [4][4]     = { "*",  "1-0",  "0-1",  "=-="     };
const char RESULT_LONGSTR [4][8] = { "*",  "1-0",  "0-1",  "1/2-1/2" };
const resultT RESULT_OPPOSITE [4] = {
    RESULT_None, RESULT_Black, RESULT_White, RESULT_Draw
};

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHESS PIECES, COLORS AND THEIR MACROS

const uint NUM_COLOR_TYPES = 2;
const colorT
    WHITE = 0,
    BLACK = 1,
    NOCOLOR = 2;

const char COLOR_CHAR [3] = {'W', 'B', '_' };

  inline colorT
color_Flip (colorT c) { return 1 - c; }

  inline char
color_Char(colorT c)  { return COLOR_CHAR[c]; }

const castleDirT  QSIDE = 0,  KSIDE = 1;


// PIECE TYPES (without color; same value as a white piece)

const pieceT
    KING = 1,
    QUEEN = 2,
    ROOK = 3,
    BISHOP = 4,
    KNIGHT = 5,
    PAWN = 6;

// PIECES:
//   Note that color(x) == ((x & 0x8) >> 3)  and  type(x) == (x & 0x7)
//   EMPTY is deliberately nonzero, and END_OF_BOARD is zero, so that
//   a board can be used as a regular 0-terminated string, provided
//   that board[NULL_SQUARE] == END_OF_BOARD, as it always should be.

const pieceT  EMPTY = 7;
const pieceT  END_OF_BOARD = 0;
const pieceT  WK =  1, WQ =  2, WR =  3, WB =  4, WN =  5, WP =  6;
const pieceT  BK =  9, BQ = 10, BR = 11, BB = 12, BN = 13, BP = 14;

// Minor piece definitions, used for searching by material only:
const pieceT  WM = 16, BM = 17;

const uint MAX_PIECE_TYPES = 18;


// PIECE_CHAR[]: array of piece characters, capitals for White pieces.

const char PIECE_CHAR [] = "xKQRBNP.xkqrbnpxMm";

// PIECE_FLIP[]: array of pieces, with colors reversed.

const pieceT PIECE_FLIP [MAX_PIECE_TYPES] = {
    END_OF_BOARD,
    BK, BQ, BR, BB, BN, BP,
    EMPTY, EMPTY,
    WK, WQ, WR, WB, WN, WP,
    EMPTY, BM, WM
};

const bool PIECE_IS_SLIDER [8] = {
    false,
    false, true, true, true, false, false,
    false,
};

// PIECE_VALUE: Piece values, K=1000, Q=9, R=5, B=N=3, P=1

const int PIECE_VALUE [MAX_PIECE_TYPES] = {
    0,
    100, 9, 5, 3, 3, 1,
    0, 0,
    -100, -9, -5, -3, -3, -1,
    0, 3, -3
};

//
// INLINE FUNCTIONS for pieces
//

  inline colorT
piece_Color(pieceT p)  { return (p == EMPTY) ? NOCOLOR : ((p & 8) >> 3); }

// Slightly faster piece_Color when we are sure the piece is not empty:
  inline colorT
piece_Color_NotEmpty(pieceT p)  { return (p & 8) >> 3; }

  inline pieceT
piece_Type(pieceT p)  { return (p & 7); }

  inline pieceT
piece_Make(colorT c, pieceT p)  { return ((c << 3) | (p & 7)); }

  inline bool
piece_IsWhite(pieceT p)  { return (p>=WK && p<=WP); }

  inline bool
piece_IsBlack(pieceT p)  { return (p>=BK && p<=BP); }

  inline bool
piece_IsKing(pieceT p)  { return (piece_Type(p) == KING); }

  inline bool
piece_IsQueen(pieceT p)  { return (piece_Type(p) == QUEEN); }

  inline bool
piece_IsRook(pieceT p)  { return (piece_Type(p) == ROOK); }

  inline bool
piece_IsBishop(pieceT p)  { return (piece_Type(p) == BISHOP); }

  inline bool
piece_IsKnight(pieceT p)  { return (piece_Type(p) == KNIGHT); }

  inline bool
piece_IsPawn(pieceT p)  { return (piece_Type(p) == PAWN); }

  inline bool
piece_IsSlider(pieceT p) { return PIECE_IS_SLIDER[piece_Type(p)]; }

  inline char
piece_Char(pieceT p)  { return PIECE_CHAR[piece_Type(p)]; }

  inline pieceT
piece_FromChar(char x)
{
    switch (x) {
    case 'K': return KING;
    case 'Q': return QUEEN;
    case 'R': return ROOK;
    case 'N': return KNIGHT;
    case 'B': return BISHOP;
    default:  return EMPTY;
    }
}

inline int
piece_Value (pieceT p)  { return PIECE_VALUE[p]; }


//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// SQUARES AND SQUARE MACROS

const squareT
    A1 = 0, B1 = 1, C1 = 2, D1 = 3, E1 = 4, F1 = 5, G1 = 6, H1 = 7,
    A2 = 8, B2 = 9, C2 =10, D2 =11, E2 =12, F2 =13, G2 =14, H2 =15,
    A3 =16, B3 =17, C3 =18, D3 =19, E3 =20, F3 =21, G3 =22, H3 =23,
    A4 =24, B4 =25, C4 =26, D4 =27, E4 =28, F4 =29, G4 =30, H4 =31,
    A5 =32, B5 =33, C5 =34, D5 =35, E5 =36, F5 =37, G5 =38, H5 =39,
    A6 =40, B6 =41, C6 =42, D6 =43, E6 =44, F6 =45, G6 =46, H6 =47,
    A7 =48, B7 =49, C7 =50, D7 =51, E7 =52, F7 =53, G7 =54, H7 =55,
    A8 =56, B8 =57, C8 =58, D8 =59, E8 =60, F8 =61, G8 =62, H8 =63,
    COLOR_SQUARE = 64,
    NULL_SQUARE = 65, NS = 65;    // NS is abbreviation for NULL_SQUARE.

const rankT
    RANK_1 = 0, RANK_2 = 1, RANK_3 = 2, RANK_4 = 3, RANK_5 = 4, RANK_6 = 5,
    RANK_7 = 6, RANK_8 = 7, NO_RANK = 64;

const fyleT
    // we use "fyle" instead of "file" to avoid confusion with disk files.
    A_FYLE = 0, B_FYLE = 1, C_FYLE = 2, D_FYLE = 3, E_FYLE = 4, F_FYLE = 5,
    G_FYLE = 6, H_FYLE = 7, NO_FYLE = 64;

  inline rankT
rank_FromChar(char c)
{   if (c < '1'  ||  c > '8') { return NO_RANK; } else return (c - '1');  }

  inline fyleT
fyle_FromChar(char c)
{   if (c < 'a'  ||  c > 'h') { return NO_FYLE; } else return (c - 'a');  }

  inline squareT
square_Make(fyleT f, rankT r)
{
    ASSERT (f <= H_FYLE  &&  r <= RANK_8);
    return ((r << 3) | f);
}

  inline fyleT
square_Fyle(squareT sq)
{
    return (sq & 0x7);
}

  inline rankT
square_Rank(squareT sq)
{
    return ((sq >> 3) & 0x7);
}

  inline leftDiagT
square_LeftDiag (squareT sq)
{
    return square_Rank(sq) + square_Fyle(sq);
}

  inline rightDiagT
square_RightDiag (squareT sq)
{
    return (7 + square_Rank(sq) - square_Fyle(sq));
}

// square_Color:
//   Return WHITE for a light square, BLACK for a dark square.
  inline colorT
square_Color (squareT sq)
{
    return 1 - (square_LeftDiag(sq) & 1);
}

// square_FlipFyle:
//   Return the square with its file flipped: a1 <-> h1, b1 <-> g1, etc.
  inline squareT
square_FlipFyle (squareT sq)
{
    return square_Make (A_FYLE + H_FYLE - square_Fyle(sq), square_Rank(sq));
}

// square_FlipRank:
//   Return the square with its rank flipped: a1 <-> a8, a2 <-> a7, etc.
  inline squareT
square_FlipRank (squareT sq)
{
    return square_Make (square_Fyle(sq), RANK_1 + RANK_8 - square_Rank(sq));
}

// square_FlipDiag:
//   Return the square flipped along the a1-h8 diagonal.
  inline squareT
square_FlipDiag (squareT sq)
{
    return square_Make (square_Rank(sq), square_Fyle(sq));
}

const uint
rankFyleDist[64] = {
    0, 1, 2, 3, 4, 5, 6, 7,
    1, 0, 1, 2, 3, 4, 5, 6,
    2, 1, 0, 1, 2, 3, 4, 5,
    3, 2, 1, 0, 1, 2, 3, 4,
    4, 3, 2, 1, 0, 1, 2, 3,
    5, 4, 3, 2, 1, 0, 1, 2,
    6, 5, 4, 3, 2, 1, 0, 1,
    7, 6, 5, 4, 3, 2, 1, 0
};

// square_Distance:
//   Return the distance in king moves between two squares.
  inline uint
square_Distance (squareT from, squareT to)
{
    ASSERT (from <= H8  &&  to <= H8);
    uint rankd = rankFyleDist[(square_Rank(from) << 3) | square_Rank(to)];
    uint fyled = rankFyleDist[(square_Fyle(from) << 3) | square_Fyle(to)];
    return (rankd > fyled) ? rankd : fyled;
}

// square_NearestCorner:
//   Return the corner (A1/H1/A8/H8) closest to the specified square.
  inline squareT
square_NearestCorner (squareT sq)
{
    if (square_Rank(sq) <= RANK_4) {
        return (square_Fyle(sq) <= D_FYLE)? A1 : H1;
    } else {
        return (square_Fyle(sq) <= D_FYLE)? A8 : H8;
    }
}

  inline bool
square_IsCornerSquare (squareT sq)
{
    return (sq == A1  ||  sq == H1  ||  sq == A8  ||  sq == H8);
}

  inline bool
square_IsEdgeSquare (squareT sq)
{
    rankT rank = square_Rank(sq);
    if (rank == RANK_1  ||  rank == RANK_8) { return true; }
    fyleT fyle = square_Fyle(sq);
    if (fyle == A_FYLE  ||  fyle == H_FYLE) { return true; }
    return false;
}

const int edgeDist[66] = {
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 1, 1, 1, 1, 1, 1, 0,
    0, 1, 2, 2, 2, 2, 1, 0,
    0, 1, 2, 3, 3, 2, 1, 0,
    0, 1, 2, 3, 3, 2, 1, 0,
    0, 1, 2, 2, 2, 2, 1, 0,
    0, 1, 1, 1, 1, 1, 1, 0,
    0, 0, 0, 0, 0, 0, 0, 0,
    -1, -1
};

  inline int
square_EdgeDistance (squareT sq)
{
    return edgeDist[sq];
}

  inline bool
square_IsKnightHop (squareT from, squareT to)
{
    ASSERT (from <= H8  &&  to <= H8);
    uint rdist = rankFyleDist [(square_Rank(from) << 3) | square_Rank(to)];
    uint fdist = rankFyleDist [(square_Fyle(from) << 3) | square_Fyle(to)];
    // It is a knight hop only if one distance is two squares and the
    // other is one square -- that is, only if their product equals two.
    return ((rdist * fdist) == 2);
}

  inline char
square_FyleChar (squareT sq)
{
    return square_Fyle(sq) + 'a';
}

  inline char
square_RankChar (squareT sq)
{
    return square_Rank(sq) + '1';
}

  inline void
square_Print (squareT sq, char * str)
{
    if (sq <= H8) {
        str[0] = square_FyleChar(sq);
        str[1] = square_RankChar(sq);
        str[2] = 0;
    } else if (sq == NULL_SQUARE) {
        str[0] = 'N'; str[1] = 'S'; str[2] = 0;
    } else {
        str[0] = 'X'; str[1] = 'X'; str[2] = 0;
    }
    return;
}

// Directions:
// Up = 1, Down = 2, Left = 4, Right = 8, UpLeft = 5, UpRight = 9,
// DownLeft = 6, DownRight = 10

const directionT
    NULL_DIR = 0,
    UP = 1,
    DOWN = 2,
    LEFT = 4,
    RIGHT = 8,
    UP_LEFT = (UP | LEFT),
    UP_RIGHT = (UP | RIGHT),
    DOWN_LEFT = (DOWN | LEFT),
    DOWN_RIGHT = (DOWN | RIGHT);

const directionT dirOpposite[11] = {
    NULL_DIR,
    DOWN,       // opposite of UP (1)
    UP,         // opposite of DOWN (2)
    NULL_DIR,
    RIGHT,      // opposite of LEFT (4)
    DOWN_RIGHT, // opposite of UP_LEFT (5)
    UP_RIGHT,   // opposite of DOWN_LEFT (6)
    NULL_DIR,
    LEFT,       // opposite of RIGHT (8)
    DOWN_LEFT,  // opposite of UP_RIGHT (9)
    UP_LEFT     // opposite of DOWN_RIGHT (10)
};

// direction_Opposite(): return the opposite direction to d
  inline directionT
direction_Opposite (directionT d)
{
    return dirOpposite[d];
}

// dirIsDiagonal[]: array listing the diagonal directions, for fast
//      lookup of whether a direction is a diagonal.
  const bool
dirIsDiagonal [11] = {
    false,   //  0 = NULL_DIR
    false,   //  1 = UP
    false,   //  2 = DOWN
    false,   //  3 = Invalid
    false,   //  4 = LEFT
    true,    //  5 = UP_LEFT
    true,    //  6 = DOWN_LEFT
    false,   //  7 = Invalid
    false,   //  8 = RIGHT
    true,    //  9 = UP_RIGHT
    true     // 10 = DOWN_RIGHT
};

  inline bool
direction_IsDiagonal (directionT dir)
{
    return dirIsDiagonal[dir];
}

// dirDelta:
//   Array giving the board delta of moving to the next square
//   in that direction.
  const int
dirDelta[11] = {
    0,    // NULL_DIR
    8,    // UP
   -8,    // DOWN
    0,    // Invalid
   -1,    // LEFT
    7,    // UP_LEFT
   -9,    // DOWN_LEFT
    0,    // Invalid
    1,    // RIGHT
    9,    // UP_RIGHT
   -7     // DOWN_RIGHT
};

  inline int
direction_Delta (directionT dir)
{
    return dirDelta[dir];
}

// sqDir[][]: Array listing the direction between any two squares.
//    For example, sqDir[A1][B2] == UP_RIGHT, and sqDir[A1][C2] == NULL_DIR.
//    It is initialised with the function sqDir_Init() in misc.cpp
extern directionT  sqDir[66][66];

// sqMove[66][11]: a table of the square resulting from a move in a
//    certain direction from a square.
//    For example, sqMove[A1][UP] == A2; sqMove[A1][DOWN] == NULL_SQUARE.
#include "sqmove.h"

// square_Move(): Return the new square resulting from moving in
//      direction d from x.
  inline squareT
square_Move(squareT sq, directionT dir)
{
    return sqMove[sq][dir];
}

// square_Last():
//   Return the last square reached by moving as far as possible in
//   the direction d from the square sq. If sq is a valid on-board
//   square and d is a valid direction, the result will always be
//   a valid on-board square; the result will be the same as the
//   input square if moving in the specified direction would end
//   up off the board.
  inline squareT
square_Last (squareT sq, directionT dir)
{
    return sqLast[sq][dir];
}


// The starting Board
//
  const boardT
START_BOARD =
{
    WR, WN, WB, WQ, WK, WB, WN, WR,    // A1--H1
    WP, WP, WP, WP, WP, WP, WP, WP,    // A2--H2
    EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY,
    EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY,
    EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY,
    EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY,
    BP, BP, BP, BP, BP, BP, BP, BP,
    BR, BN, BB, BQ, BK, BB, BN, BR,
    EMPTY, // COLOR_SQUARE
    END_OF_BOARD  // NULL_SQUARE
};


// Square colors for the standard chess board:
//
  const colorT
BOARD_SQUARECOLOR[66] = {
    BLACK, WHITE, BLACK, WHITE, BLACK, WHITE, BLACK, WHITE,  // a1-h1
    WHITE, BLACK, WHITE, BLACK, WHITE, BLACK, WHITE, BLACK,  // a2-h2
    BLACK, WHITE, BLACK, WHITE, BLACK, WHITE, BLACK, WHITE,  // a3-h3
    WHITE, BLACK, WHITE, BLACK, WHITE, BLACK, WHITE, BLACK,  // a4-h4
    BLACK, WHITE, BLACK, WHITE, BLACK, WHITE, BLACK, WHITE,  // a5-h5
    WHITE, BLACK, WHITE, BLACK, WHITE, BLACK, WHITE, BLACK,  // a6-h6
    BLACK, WHITE, BLACK, WHITE, BLACK, WHITE, BLACK, WHITE,  // a7-h7
    WHITE, BLACK, WHITE, BLACK, WHITE, BLACK, WHITE, BLACK,  // a8-h8
    NOCOLOR, NOCOLOR  // Color square and Null square
};

  inline int
board_Compare (const pieceT * b1, const pieceT * b2)
{
    for (uint i=0; i < 64; i++) {
        if (*b1 < *b2) { return -1; }
        if (*b1 > *b2) { return 1; }
        b1++; b2++;
    }
    return 0;
}

// square_Adjacent: returns 1 if the two squares are adjacent. Note that
//    diagonal adjacency is included: a1 and b2 are adjacent.
//    Also note that a square is adjacent to itself.
  inline bool
square_Adjacent (squareT from, squareT to)
{
    ASSERT (from <= H8  &&  to <= H8);
    rankT fromRank = square_Rank(from);
    rankT toRank = square_Rank(to);
    int rdist = (int)fromRank - (int)toRank;
    if (rdist < -1  ||  rdist > 1) { return false; }
    fyleT fromFyle = square_Fyle(from);
    fyleT toFyle = square_Fyle(to);
    int fdist = (int)fromFyle - (int)toFyle;
    if (fdist < -1  ||  fdist > 1) { return false; }
    return true;
}

// Random values:
//   To ensure good bit distributions, we take three random values
//   and mix the bits around.

inline void srandom32(uint seed) {
#ifdef _WIN32
    srand (seed);
#else
    srandom (seed);
#endif
}

inline uint random32()
{
#ifdef _WIN32
    return rand() ^ (rand() << 16) ^ (rand() >> 16);
#else
    return random() ^ (random() << 16) ^ (random() >> 16);
#endif
}

#endif  // #ifdef SCID_COMMON_H

//////////////////////////////////////////////////////////////////////
//  EOF:  common.h
//////////////////////////////////////////////////////////////////////

