/*
 * genmoves.c - C source for GNU CHESS
 *
 * Copyright (c) 1988,1989,1990 John Stanback
 * Copyright (c) 1992 Free Software Foundation
 *
 * This file is part of GNU CHESS.
 *
 * GNU Chess is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * GNU Chess is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU Chess; see the file COPYING.  If not, write to
 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#include "gnuchess.h"
#include "ataks.h"
SHORT *TrP, InCheck;

#define Link(from,to,flag,s) \
{\
   node->f = from; node->t = to;\
     node->reply = 0;\
       node->flags = flag;\
	 node->score = s;\
	   ++node;\
	     (*TrP)++;\
	     }

inline int
CheckMove (SHORT f, SHORT t, SHORT flag)
{
  SHORT side, incheck;
  SHORT tempb, tempc, tempsf, tempst;   
  struct leaf node;

  side = color[f];
  node.f = f;
  node.t = t;
  node.flags = flag;
  MakeMove (side, &node, &tempb, &tempc, &tempsf, &tempst);
  incheck = SqAtakd (PieceList[side][0], 1 ^ side);
  UnmakeMove (side, &node, &tempb, &tempc, &tempsf, &tempst);
  return (!incheck);
}



inline void
LinkMove (SHORT ply, SHORT f,
	  register SHORT t,
	  SHORT flag,
	  SHORT 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.
 */

{
    register SHORT s = 0;
#if defined HISTORY
    register SHORT z;
#endif
    register utshort mv;
    SHORT piece;
    register struct leaf *node;

    node = &Tree[*TrP];
    mv = (f << 8) | t;
    piece = board[f];
#ifdef KILLT
    s += killt[mv ];
#endif
#ifdef HISTORY
    z = mv;
    if (xside == white)
	z |= 0x4000;
    s += history[z];
#endif
    if (color[t] != neutral)
      {
	  /* TOsquare is the square the last piece moved moved to */
	  s += value[board[t]] - piece + ((t == TOsquare) ? 500 : 0);
      }
    if (board[f] == pawn)
	if (row (t) == 0 || row (t) == 7)
	  {
	      flag |= promote;
	      s += 800;
#if !defined CHESSTOOL
	      Link (f, t, flag | queen, s - 20000);
	      s -= 200;
	      Link (f, t, flag | rook, s - 20000);
	      s -= 50;
	      Link (f, t, flag | knight, s - 20000);
	      flag |= bishop;
	      s -= 50;
#else
	      flag |= queen;
#endif
	  }
	else if (row (t) == 1 || row (t) == 6)
	  {
	      flag |= pwnthrt;
	      s += 600;
	  }
	else if ((row (t) == ((color[f] == white) ? 5 : 2)) && (ply > MINDEPTH) && (ply < Sdepth + 3))
	  {
	      if ((mtl[white] - pmtl[white] + mtl[black] - pmtl[black]) < PTVALUE)
		{
		    flag |= pwnthrt;
		    s += 400;
		}
	  }
    Link (f, t, flag, s - 20000);
}

inline
void
GenMoves (register SHORT ply, register SHORT sq, SHORT side, SHORT 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;
    register UCHAR *ppos, *pdir;


    TrP = &TrPnt[ply + 1];
    piece = board[sq];
    if (piece == pawn)
      {
          ppos = nextpos[ptype[side][piece]][sq];
          pdir = nextdir[ptype[side][piece]][sq];
	  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 /*&& board[u] != king*/)
	    {
		      LinkMove (ply, sq, u, capture, xside);
	    }
	  u = pdir[u];
	  if (color[u] == xside /*&& board[u] != king*/)
	    {
		      LinkMove (ply, sq, u, capture, xside);
	    }
      }
    else
      {
	  ppos = nextpos[piece][sq];
	  pdir = nextdir[piece][sq];
	  u = ppos[sq];
	  do
	    {
		if (color[u] == neutral)
		  {
			    LinkMove (ply, sq, u, 0, xside);
		      u = ppos[u];
		  }
		else
		  {
		      if (color[u] == xside /*&& board[u] != king*/)
			{
				  LinkMove (ply, sq, u, capture, xside);
			}
		      u = pdir[u];
		  }
	    }
	  while (u != sq);
      }
}

void
MoveList (SHORT side, register 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.
 */

{
    register SHORT i, xside, f;

    xside = side ^ 1;
    TrP = &TrPnt[ply + 1];
    *TrP = TrPnt[ply];
    if (!PV)
	Swag0 = killr0[ply];
    else
	Swag0 = PV;
    Swag1 = killr1[ply];
    Swag2 = killr2[ply];
    if (ply > 2)
	Swag4 = killr1[ply - 2];
    else
	Swag4 = 0;
#ifdef KILLT
    killt[SwagHt ] += 5000;
    killt[Swag0 ] += 2000;
    killt[Swag1 ] += 60;
    killt[Swag2 ] += 50;
    killt[Swag4 ] += 30;
#endif
    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);
	    }
      }
    if (epsquare > 0)
      {
/*	  register SHORT l; */

	  f = epmove1[epsquare];
	  if (color[f] == side && board[f] == pawn)
	    {
/*		l = epsquare + ((epsquare > f) ? -8 : 8);
		board[l] = no_piece;
		color[l] = neutral; */
		LinkMove (ply, f, epsquare, capture | epmask, xside);
/*		board[l] = pawn;
		color[l] = xside; */
	    }
	  f = epmove2[epsquare];
	  if (color[f] == side && board[f] == pawn)
	    {
/*		l = epsquare + ((epsquare > f) ? -8 : 8);
		board[l] = no_piece;
		color[l] = neutral; */
		LinkMove (ply, f, epsquare, capture | epmask, xside);
/*		board[l] = pawn;
		color[l] = xside; */
	    }
      }
#ifdef KILLT
    killt[SwagHt ] -= 5000;
    killt[Swag0 ] -= 2000;
    killt[Swag1 ] -= 60;
    killt[Swag2 ] -= 50;
    killt[Swag4 ] -= 30;
#endif
    SwagHt = 0;			/* SwagHt is only used once */
    GenCnt += (TrPnt[ply + 1] - TrPnt[ply]);
}

void
CaptureList (register SHORT side, SHORT ply)

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

{
    register SHORT u, sq;
    register UCHAR *ppos, *pdir;
    struct leaf *node;
    SHORT i, piece, *PL, r7;
    SHORT xside = side^1;

    xside = side ^ 1;
    TrP = &TrPnt[ply + 1];
    *TrP = TrPnt[ply];
    node = &Tree[*TrP];
    r7 = rank7[side];
    PL = PieceList[side];

    for (i = 0; i <= PieceCnt[side]; i++)
      {
	  sq = PL[i];
	  piece = board[sq];
	  if (sweep[piece])
	    {
		ppos = nextpos[piece][sq];
		pdir = nextdir[piece][sq];
		u = ppos[sq];
		do
		  { 
		    if (color[u] == neutral) 
			u = ppos[u];
		    else 
		      {
			if (color[u] == xside) 
			  {
			    Link (sq, u, capture, value[board[u]] + svalue[u] - piece); 
			  }
			u = pdir[u];
		      } 
		  }
		while (u != sq);
	    } else {
		pdir = nextdir[ptype[side][piece]][sq];
		if (piece == pawn && row (sq) == r7)
		  {
		      u = pdir[sq];
		      if (color[u] == xside)
			{
			  Link (sq, u, capture | promote | queen, valueQ);
#if !defined CHESSTOOL
			    Link (sq, u, capture | promote | rook, valueR);
			    Link (sq, u, capture | promote | knight, valueN);
			    Link (sq, u, capture | promote | bishop, valueB);
#endif
		      }
		      u = pdir[u];
		      if (color[u] == xside)
			{
			    Link (sq, u, capture | promote | queen, valueQ);
#if !defined CHESSTOOL
			    Link (sq, u, capture | promote | rook, valueR);
			    Link (sq, u, capture | promote | knight, valueN);
			    Link (sq, u, capture | promote | bishop, valueB);
#endif
			}
		      ppos = nextpos[ptype[side][piece]][sq];
		      u = ppos[sq];	/* also generate non capture promote */
		      if (color[u] == neutral)
			{
			    Link (sq, u, promote | queen, valueQ);
#if !defined CHESSTOOL
			    Link (sq, u, promote | rook, valueR);
			    Link (sq, u, promote | knight, valueN);
			    Link (sq, u, promote | bishop, valueB);
#endif
			}
		  }
		else
		  {
		      u = pdir[sq];
		      do
			{
			    if (color[u] == xside)
				Link (sq, u, capture, value[board[u]] + svalue[u] - piece);
			    u = pdir[u];
			}
		      while (u != sq);
		  }
	    }
      }
    SwagHt = 0;			/* SwagHt is only used once */
    GenCnt += (TrPnt[ply + 1] - TrPnt[ply]);
}

inline
void
VGenMoves (register SHORT ply, register SHORT sq, SHORT side, SHORT 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;
    register UCHAR *ppos, *pdir;


    TrP = &TrPnt[ply + 1];
    piece = board[sq];
    ppos = nextpos[ptype[side][piece]][sq];
    pdir = nextdir[ptype[side][piece]][sq];
    if (piece == pawn)
      {
	  u = ppos[sq];		/* follow no captures thread */
	  if (color[u] == neutral)
	    {
		if (CheckMove (sq, u, 0))
		  {
		      LinkMove (ply, sq, u, 0, xside);
		  }
		u = ppos[u];
		if (color[u] == neutral)
		    if (CheckMove (sq, u, 0))
		      {
			  LinkMove (ply, sq, u, 0, xside);
		      }
	    }
	  u = pdir[sq];		/* follow captures thread */
	  if (color[u] == xside /* && board[u] != king */)
	    {
		if (CheckMove (sq, u, capture))
		  {
		      LinkMove (ply, sq, u, capture, xside);
		  }
	    }
	  u = pdir[u];
	  if (color[u] == xside /*&& board[u] != king*/)
	    {
		if (CheckMove (sq, u, capture))
		  {
		      LinkMove (ply, sq, u, capture, xside);
		  }
	    }
      }
    else
      {
	  u = ppos[sq];
	  do
	    {
		if (color[u] == neutral)
		  {
		      if (CheckMove (sq, u, 0))
			{
			    LinkMove (ply, sq, u, 0, xside);
			}
		      u = ppos[u];
		  }
		else
		  {
		      if (color[u] == xside /*&& board[u] != king */)
			{
			    if (CheckMove (sq, u, capture))
			      {
				  LinkMove (ply, sq, u, capture, xside);
			      }
			}
		      u = pdir[u];
		  }
	    }
	  while (u != sq);
      }
}

void
VMoveList (SHORT side, register 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.
 */

{
    register SHORT i, xside, f;

    xside = side ^ 1;
    TrP = &TrPnt[ply + 1];
    *TrP = TrPnt[ply];
    InCheck = SqAtakd (PieceList[side][0], side ^ 1);
    if (!PV)
	Swag0 = killr0[ply];
    else
	Swag0 = PV;
    Swag1 = killr1[ply];
    Swag2 = killr2[ply];
    if (ply > 2)
	Swag4 = killr1[ply - 2];
    else
	Swag4 = 0;
#ifdef KILLT
    killt[SwagHt] += 5000;
    killt[Swag0] += 2000;
    killt[Swag1] += 60;
    killt[Swag2] += 50;
    killt[Swag4] += 30;
#endif
    for (i = PieceCnt[side]; i >= 0; i--)
	VGenMoves (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);
	    }
      }
    if (epsquare > 0)
      {
	  register SHORT l;

	  f = epmove1[epsquare];
	  if (color[f] == side && board[f] == pawn)
	    {
		l = epsquare + ((epsquare > f) ? -8 : 8);
		board[l] = no_piece;
		color[l] = neutral;
		if (CheckMove (f, epsquare, capture | epmask))
		  {
		      LinkMove (ply, f, epsquare, capture | epmask, xside);
		  }
		board[l] = pawn;
		color[l] = xside;
	    }
	  f = epmove2[epsquare];
	  if (color[f] == side && board[f] == pawn)
	    {
		l = epsquare + ((epsquare > f) ? -8 : 8);
		board[l] = no_piece;
		color[l] = neutral;
		if (CheckMove (f, epsquare, capture | epmask))
		  {
		      LinkMove (ply, f, epsquare, capture | epmask, xside);
		  }
		board[l] = pawn;
		color[l] = xside;
	    }
      }
#ifdef KILLT
    killt[SwagHt] -= 5000;
    killt[Swag0] -= 2000;
    killt[Swag1] -= 60;
    killt[Swag2] -= 50;
    killt[Swag4] -= 30;
#endif
    SwagHt = 0;			/* SwagHt is only used once */
    GenCnt += (TrPnt[ply + 1] - TrPnt[ply]);
}