/*
  C source for Winsock Chess
  
  Revision 1994-03-15
  Modified by Donald Munro for use as a 2 player chess game over a 
  WINSOCK layer on a TCP (or other WinSock supporting) network.
  Source code and make files for MS Visual C/C++ V1.00/1.50.
  February/March 1994
  All GNU copyright and distribution conditions as described below and in the
  file COPYING also apply to WinSock Chess.
  This module is adapted from GNU Chess.

  C source for GNU CHESS

  Revision: 1990-09-30

  Modified by Daryl Baker for use in MS WINDOWS environment

  Copyright (C) 1986, 1987, 1988, 1989, 1990 Free Software Foundation, Inc.
  Copyright (c) 1988, 1989, 1990  John Stanback

  This file is part of CHESS.

  CHESS is distributed in the hope that it will be useful, but WITHOUT ANY
  WARRANTY.  No author or distributor accepts responsibility to anyone for
  the consequences of using it or for whether it serves any particular
  purpose or works at all, unless he says so in writing.  Refer to the CHESS
  General Public License for full details.

  Everyone is granted permission to copy, modify and redistribute CHESS, but
  only under the conditions described in the CHESS General Public License.
  A copy of this license is supposed to have been given to you along with
  CHESS so you can know your rights and responsibilities.  It should be in a
  file named COPYING.  Among other things, the copyright notice and this
  notice must be preserved on all copies.
*/

#define NOATOM 
#define NOCLIPBOARD
#define NOCREATESTRUCT
#define NOFONT
#define NOREGION
#define NOSOUND
#define NOWH
#define NOWINOFFSETS
#define NOCOMM
#define NOKANJI

#include <windows.h>
#include <string.h>
#include <time.h>
#include <stdlib.h>
#include <malloc.h>
#include <stdio.h>

#include "gnuchess.h"
#include "defs.h"

/*
  hashbd contains a 32 bit "signature" of the board position. hashkey
  contains a 16 bit code used to address the hash table. When a move is
  made, XOR'ing the hashcode of moved piece on the from and to squares with
  the hashbd and hashkey values keeps things current.
*/
#define UpdateHashbd(side, piece, f, t) \
{\
  if ((f) >= 0)\
    {\
      hashbd ^= (hashcode+(side)*7*64+(piece)*64+f)->bd;\
      hashkey ^= (hashcode+(side)*7*64+(piece)*64+f)->key;\
    }\
  if ((t) >= 0)\
    {\
      hashbd ^= (hashcode+(side)*7*64+(piece)*64+t)->bd;\
      hashkey ^= (hashcode+(side)*7*64+(piece)*64+t)->key;\
    }\
}


#if ttblsz
extern unsigned long hashkey, hashbd;
/*extern struct hashval hashcode[2][7][64];*/
/*extern struct hashentry huge ttable[2][ttblsz];*/
extern struct hashval far *hashcode;
extern struct hashentry far *ttable;
#endif /* ttblsz */

/*extern unsigned char history[8192];*/
extern unsigned char far * history;

extern short rpthash[2][256];
/*extern unsigned char nextpos[8][64][64];*/
/*extern unsigned char nextdir[8][64][64];*/
extern unsigned char far *nextpos;
extern unsigned char far *nextdir;

extern short FROMsquare, TOsquare, Zscore, zwndw;
extern unsigned short PV, Swag0, Swag1, Swag2, Swag3, Swag4;
extern unsigned short killr0[maxdepth], killr1[maxdepth];
extern unsigned short killr2[maxdepth], killr3[maxdepth];
extern short Pscore[maxdepth], Tscore[maxdepth];
extern unsigned long hashkey, hashbd;
extern short ChkFlag[maxdepth], CptrFlag[maxdepth], PawnThreat[maxdepth];
extern short mtl[2], pmtl[2], emtl[2], hung[2];
extern short player, xwndw, rehash;
extern short PieceCnt[2];
extern long NodeCnt, ETnodes, EvalNodes, HashCnt, FHashCnt, HashCol;
extern short HasKnight[2], HasBishop[2], HasRook[2], HasQueen[2];
extern short Pindex[64];

static short _based(_segname("_CODE")) rank7[3] = {6, 1, 0};
static short _based(_segname("_CODE")) kingP[3] = {4, 60, 0};
static short _based(_segname("_CODE")) value[7] =
{0, valueP, valueN, valueB, valueR, valueQ, valueK};

static short _based(_segname("_CODE")) sweep[8] =
{false, false, false, true, true, true, false, false};

static short _based(_segname("_CODE")) ptype[2][8] = {
  no_piece, pawn, knight, bishop, rook, queen, king, no_piece,
  no_piece, bpawn, knight, bishop, rook, queen, king, no_piece};

static short _based(_segname("_CODE")) control[7] =
{0, ctlP, ctlN, ctlB, ctlR, ctlQ, ctlK};


void ZeroRPT (void)
{
  register int side, i;

  for (side = white; side <= black; side++)
    for (i = 0; i < 256; i++)
      rpthash[side][i] = 0;
}

int castle (short int side, short int kf, short int kt, short int iop)

/* Make or Unmake a castling move. */

{
  short rf, rt, t0, xside;

  xside = otherside[side];
  if (kt > kf)
    {
      rf = kf + 3;
      rt = kt - 1;
    }
  else
    {
      rf = kf - 4;
      rt = kt + 1;
    }
  if (iop == 0)
    {
      if (kf != kingP[side] ||
          board[kf] != king ||
          board[rf] != rook ||
          Mvboard[kf] != 0 ||
          Mvboard[rf] != 0 ||
          color[kt] != neutral ||
          color[rt] != neutral ||
          color[kt - 1] != neutral ||
          SqAtakd (kf, xside) ||
          SqAtakd (kt, xside) ||
          SqAtakd (rt, xside))
        return (false);
    }
  else
    {
      if (iop == 1)
        {
          castld[side] = true;
          Mvboard[kf]++;
          Mvboard[rf]++;
        }
      else
        {
          castld[side] = false;
          Mvboard[kf]--;
          Mvboard[rf]--;
          t0 = kt;
          kt = kf;
          kf = t0;
          t0 = rt;
          rt = rf;
          rf = t0;
        }
      board[kt] = king;
      color[kt] = side;
      Pindex[kt] = 0;
      board[kf] = no_piece;
      color[kf] = neutral;
      board[rt] = rook;
      color[rt] = side;
      Pindex[rt] = Pindex[rf];
      board[rf] = no_piece;
      color[rf] = neutral;
      PieceList[side][Pindex[kt]] = kt;
      PieceList[side][Pindex[rt]] = rt;
#if ttblsz
      UpdateHashbd (side, king, kf, kt);
      UpdateHashbd (side, rook, rf, rt);
#endif /* ttblsz */
    }
  return (true);
}


static inline void
EnPassant (short int xside, short int f, short int t, short int iop)

/*
  Make or unmake an en passant move.
*/

{
  register short l;

  if (t > f)
    l = t - 8;
  else
    l = t + 8;
  if (iop == 1)
    {
      board[l] = no_piece;
      color[l] = neutral;
    }
  else
    {
      board[l] = pawn;
      color[l] = xside;
    }
  InitializeStats ();
}


static inline void
UpdatePieceList (short int side, short int sq, short int iop)

/*
  Update the PieceList and Pindex arrays when a piece is captured or when a
  capture is unmade.
*/

{
  register short i;
  if (iop == 1)
    {
      PieceCnt[side]--;
      for (i = Pindex[sq]; i <= PieceCnt[side]; i++)
        {
          PieceList[side][i] = PieceList[side][i + 1];
          Pindex[PieceList[side][i]] = i;
        }
    }
  else
    {
      PieceCnt[side]++;
      PieceList[side][PieceCnt[side]] = sq;
      Pindex[sq] = PieceCnt[side];
    }
}

void
ZeroTTable (void)
{
  register int side, i;

  if (flag.hash)
    for (side = white; side <= black; side++)
      for (i = 0; i < ttblsz; i++)
/*        ttable[side][i].depth = 0; */
        (ttable+side*2+i)->depth = 0;
}

#define Link(from,to,flag,s) \
{\
   node->f = from; node->t = to;\
     node->reply = 0;\
       node->flags = flag;\
         node->score = s;\
           ++node;\
             ++TrPnt[ply+1];\
             }

static inline void
LinkMove (short int ply,
          short int f,
          short int t,
          short int flag,
          short int xside)

/*
  Add a move to the tree.  Assign a bonus to order the moves
  as follows:
  1. Principle variation
  2. Capture of last moved piece
  3. Other captures (major pieces first)
  4. Killer moves
  5. "history" killers
*/

{
  register short s, z;
  unsigned short mv;
  struct leaf far *node;

  node = &Tree[TrPnt[ply + 1]];
  mv = (f << 8) | t;
  s = 0;
  if (mv == Swag0)
    s = 2000;
  else if (mv == Swag1)
    s = 60;
  else if (mv == Swag2)
    s = 50;
  else if (mv == Swag3)
    s = 40;
  else if (mv == Swag4)
    s = 30;
  z = (f << 6) | t;
  if (xside == white)
    z |= 0x1000;
/*  s += history[z]; */
  s += *(history+z);
  if (color[t] != neutral)
    {
      if (t == TOsquare)
        s += 500;
      s += value[board[t]] - board[f];
    }
  if (board[f] == pawn)
    if (row (t) == 0 || row (t) == 7)
      {
        flag |= promote;
        s += 800;
        Link (f, t, flag | queen, s - 20000);
        s -= 200;
        Link (f, t, flag | knight, s - 20000);
        s -= 50;
        Link (f, t, flag | rook, s - 20000);
        flag |= bishop;
        s -= 50;
      }
    else if (row (t) == 1 || row (t) == 6)
      {
        flag |= pwnthrt;
        s += 600;
      }
  Link (f, t, flag, s - 20000);
}


static inline void
GenMoves (short int ply, short int sq, short int side, short int xside)

/*
  Generate moves for a piece. The moves are taken from the precalulated
  array nextpos/nextdir. If the board is free, next move is choosen from
  nextpos else from nextdir.
*/

{
  register short u, piece;
  unsigned char far *ppos, far *pdir;

  piece = board[sq];
  ppos = nextpos+ptype[side][piece]*64*64+sq*64;
  pdir = nextdir+ptype[side][piece]*64*64+sq*64;
  if (piece == pawn)
    {
      u = ppos[sq];     /* follow no captures thread */
      if (color[u] == neutral)
        {
          LinkMove (ply, sq, u, 0, xside);
          u = ppos[u];
          if (color[u] == neutral)
            LinkMove (ply, sq, u, 0, xside);
        }
      u = pdir[sq];     /* follow captures thread */
      if (color[u] == xside)
        LinkMove (ply, sq, u, capture, xside);
      else
        if (u == epsquare)
          LinkMove (ply, sq, u, capture | epmask, xside);
      u = pdir[u];
      if (color[u] == xside)
        LinkMove (ply, sq, u, capture, xside);
      else
        if (u == epsquare)
          LinkMove (ply, sq, u, capture | epmask, xside);
    }
  else
    {
      u = ppos[sq];
      do
        {
          if (color[u] == neutral)
            {
              LinkMove (ply, sq, u, 0, xside);
              u = ppos[u];
            }
          else
            {
              if (color[u] == xside)
                LinkMove (ply, sq, u, capture, xside);
              u = pdir[u];
            }
      } while (u != sq);
    }
}


void
MoveList (short int side, short ply)

/*
  Fill the array Tree[] with all available moves for side to play. Array
  TrPnt[ply] contains the index into Tree[] of the first move at a ply.
*/

{
  short i, xside, f;

  //ply = 2;
  xside = otherside[side];
  TrPnt[ply + 1] = TrPnt[ply];
  if (PV == 0)
    Swag0 = killr0[ply];
  else
    Swag0 = PV;
  Swag1 = killr1[ply];
  Swag2 = killr2[ply];
  Swag3 = killr3[ply];
  if (ply > 2)
    Swag4 = killr1[ply - 2];
  else
    Swag4 = 0;
  for (i = PieceCnt[side]; i >= 0; i--)
    GenMoves (ply, PieceList[side][i], side, xside);
  if (!castld[side])
    {
      f = PieceList[side][0];
      if (castle (side, f, f + 2, 0))
        {
          LinkMove (ply, f, f + 2, cstlmask, xside);
        }
      if (castle (side, f, f - 2, 0))
        {
          LinkMove (ply, f, f - 2, cstlmask, xside);
        }
    }
}


void
MakeMove (short int side,
          struct leaf far * node,
          short int *tempb,
          short int *tempc,
          short int *tempsf,
          short int *tempst,
          short int *INCscore)

/*
  Update Arrays board[], color[], and Pindex[] to reflect the new board
  position obtained after making the move pointed to by node. Also update
  miscellaneous stuff that changes when a move is made.
*/

{
  short f, t, xside, ct, cf;

  xside = otherside[side];
  GameCnt++;
  f = node->f;
  t = node->t;
  epsquare = -1;
  FROMsquare = f;
  TOsquare = t;
  *INCscore = 0;
  GameList[GameCnt].gmove = (f << 8) | t;
  if (node->flags & cstlmask)
    {
      GameList[GameCnt].piece = no_piece;
      GameList[GameCnt].color = side;
      (void) castle (side, f, t, 1);
    }
  else
    {
      if (!(node->flags & capture) && (board[f] != pawn))
        rpthash[side][hashkey & 0xFF]++;
      *tempc = color[t];
      *tempb = board[t];
      *tempsf = svalue[f];
      *tempst = svalue[t];
      GameList[GameCnt].piece = *tempb;
      GameList[GameCnt].color = *tempc;
      if (*tempc != neutral)
        {
          UpdatePieceList (*tempc, t, 1);
          if (*tempb == pawn)
            --PawnCnt[*tempc][column (t)];
          if (board[f] == pawn)
            {
              --PawnCnt[side][column (f)];
              ++PawnCnt[side][column (t)];
              cf = column (f);
              ct = column (t);
              if (PawnCnt[side][ct] > 1 + PawnCnt[side][cf])
                *INCscore -= 15;
              else if (PawnCnt[side][ct] < 1 + PawnCnt[side][cf])
                *INCscore += 15;
              else if (ct == 0 || ct == 7 || PawnCnt[side][ct + ct - cf] == 0)
                *INCscore -= 15;
            }
          mtl[xside] -= value[*tempb];
          if (*tempb == pawn)
            pmtl[xside] -= valueP;
#if ttblsz
          UpdateHashbd (xside, *tempb, -1, t);
#endif /* ttblsz */
          *INCscore += *tempst;
          Mvboard[t]++;
        }
      color[t] = color[f];
      board[t] = board[f];
      svalue[t] = svalue[f];
      Pindex[t] = Pindex[f];
      PieceList[side][Pindex[t]] = t;
      color[f] = neutral;
      board[f] = no_piece;
      if (board[t] == pawn)
        if (t - f == 16)
          epsquare = f + 8;
        else if (f - t == 16)
          epsquare = f - 8;
      if (node->flags & promote)
        {
          board[t] = node->flags & pmask;
          if (board[t] == queen)
            HasQueen[side]++;
          else if (board[t] == rook)
            HasRook[side]++;
          else if (board[t] == bishop)
            HasBishop[side]++;
          else if (board[t] == knight)
            HasKnight[side]++;
          --PawnCnt[side][column (t)];
          mtl[side] += value[board[t]] - valueP;
          pmtl[side] -= valueP;
#if ttblsz
          UpdateHashbd (side, pawn, f, -1);
          UpdateHashbd (side, board[t], f, -1);
#endif /* ttblsz */
          *INCscore -= *tempsf;
        }
      if (node->flags & epmask)
        EnPassant (xside, f, t, 1);
      else
#if ttblsz
        UpdateHashbd (side, board[t], f, t);
#else
        /* NOOP */;     
#endif /* ttblsz */
      Mvboard[f]++;
    }
}

void
UnmakeMove (short int side,
            struct leaf far * node,
            short int *tempb,
            short int *tempc,
            short int *tempsf,
            short int *tempst)

/*
  Take back a move.
*/

{
  short f, t, xside;

  xside = otherside[side];
  f = node->f;
  t = node->t;
  epsquare = -1;
  GameCnt--;
  if (node->flags & cstlmask)
    (void) castle (side, f, t, 2);
  else
    {
      color[f] = color[t];
      board[f] = board[t];
      svalue[f] = *tempsf;
      Pindex[f] = Pindex[t];
      PieceList[side][Pindex[f]] = f;
      color[t] = *tempc;
      board[t] = *tempb;
      svalue[t] = *tempst;
      if (node->flags & promote)
        {
          board[f] = pawn;
          ++PawnCnt[side][column (t)];
          mtl[side] += valueP - value[node->flags & pmask];
          pmtl[side] += valueP;
#if ttblsz
          UpdateHashbd (side, (short) node->flags & pmask, -1, t);
          UpdateHashbd (side, pawn, -1, t);
#endif /* ttblsz */
        }
      if (*tempc != neutral)
        {
          UpdatePieceList (*tempc, t, 2);
          if (*tempb == pawn)
            ++PawnCnt[*tempc][column (t)];
          if (board[f] == pawn)
            {
              --PawnCnt[side][column (t)];
              ++PawnCnt[side][column (f)];
            }
          mtl[xside] += value[*tempb];
          if (*tempb == pawn)
            pmtl[xside] += valueP;
#if ttblsz
          UpdateHashbd (xside, *tempb, -1, t);
#endif /* ttblsz */
          Mvboard[t]--;
        }
      if (node->flags & epmask)
        EnPassant (xside, f, t, 2);
      else
#if ttblsz
        UpdateHashbd (side, board[f], f, t);
#else
      /* NOOP */;
#endif /* ttblsz */
      Mvboard[f]--;
      if (!(node->flags & capture) && (board[f] != pawn))
        rpthash[side][hashkey & 0xFF]--;
    }
}


void
InitializeStats (void)

/*
  Scan thru the board seeing what's on each square. If a piece is found,
  update the variables PieceCnt, PawnCnt, Pindex and PieceList. Also
  determine the material for each side and set the hashkey and hashbd
  variables to represent the current board position. Array
  PieceList[side][indx] contains the location of all the pieces of either
  side. Array Pindex[sq] contains the indx into PieceList for a given
  square.
*/

{
  short i, sq;
  
  epsquare = -1;
  for (i = 0; i < 8; i++)
    PawnCnt[white][i] = PawnCnt[black][i] = 0;
  mtl[white] = mtl[black] = pmtl[white] = pmtl[black] = 0;
  PieceCnt[white] = PieceCnt[black] = 0;
#if ttblsz
  hashbd = hashkey = 0;
#endif /* ttblsz */
  for (sq = 0; sq < 64; sq++)
    if (color[sq] != neutral)
      {
        mtl[color[sq]] += value[board[sq]];
        if (board[sq] == pawn)
          {
            pmtl[color[sq]] += valueP;
            ++PawnCnt[color[sq]][column (sq)];
          }
        if (board[sq] == king)
          Pindex[sq] = 0;
        else
          Pindex[sq] = ++PieceCnt[color[sq]];
        PieceList[color[sq]][Pindex[sq]] = sq;
#if ttblsz
        hashbd ^= (hashcode+color[sq]*7*64+board[sq]*64+sq)->bd;
        hashkey ^= (hashcode+color[sq]*7*64+board[sq]*64+sq)->key;
#endif /* ttblsz */
      }
}


int
SqAtakd (short int sq, short int side)

/*
  See if any piece with color 'side' ataks sq.  First check pawns then Queen,
  Bishop, Rook and King and last Knight.
*/

{
  register short u;
  unsigned char far *ppos, far *pdir;
  short xside;

  xside = otherside[side];
  pdir = nextdir+ptype[xside][pawn]*64*64+sq*64;
  u = pdir[sq];         /* follow captures thread */
  if (u != sq)
    {
      if (board[u] == pawn && color[u] == side)
        return (true);
      u = pdir[u];
      if (u != sq && board[u] == pawn && color[u] == side)
        return (true);
    }
  /* king capture */
  if (distance (sq, PieceList[side][0]) == 1)
    return (true);
  /* try a queen bishop capture */
  ppos = nextpos+bishop*64*64+sq*64;
  pdir = nextdir+bishop*64*64+sq*64;
  u = ppos[sq];
  do
    {
      if (color[u] == neutral)
        u = ppos[u];
      else
        {
          if (color[u] == side &&
              (board[u] == queen || board[u] == bishop))
            return (true);
          u = pdir[u];
        }
  } while (u != sq);
  /* try a queen rook capture */
  ppos = nextpos+rook*64*64+sq*64;
  pdir = nextdir+rook*64*64+sq*64;
  u = ppos[sq];
  do
    {
      if (color[u] == neutral)
        u = ppos[u];
      else
        {
          if (color[u] == side &&
              (board[u] == queen || board[u] == rook))
            return (true);
          u = pdir[u];
        }
  } while (u != sq);
  /* try a knight capture */
  pdir = nextdir+knight*64*64+sq*64;
  u = pdir[sq];
  do
    {
      if (color[u] == side && board[u] == knight)
        return (true);
      u = pdir[u];
  } while (u != sq);
  return (false);
}