#include <stdio.h>
#include <stdlib.h>
#include "chess.h"
#include "data.h"

/* modified 03/23/99 */
/*
********************************************************************************
*                                                                              *
*   GenerateCaptures() is used to generate capture and pawn promotion moves    *
*   from the current position.                                                 *
*                                                                              *
*   the destination square set is the set of squares occupied by opponent      *
*   pieces, plus the set of squares on the 8th rank that pawns can advance to  *
*   and promote.                                                               *
*                                                                              *
********************************************************************************
*/
int* GenerateCaptures(TREE *tree, int ply, int wtm, int *move) {
  register BITBOARD target, piecebd, moves;
  register BITBOARD  promotions, pcapturesl, pcapturesr;
  register int from, to, temp;

/*
 ----------------------------------------------------------
|                                                          |
|   now, produce knight moves by cycling through the       |
|   *_knight board to locate a [from] square and then      |
|   cycling through knight_attacks[] to locate to squares  |
|   that a knight on [from] attacks.                       |
|                                                          |
 ----------------------------------------------------------
*/
  if (wtm) {
    piecebd=WhiteKnights;
    while (piecebd) {
      from=LastOne(piecebd);
      moves=knight_attacks[from] & BlackPieces;
      temp=from+(knight<<12);
      while (moves) {
        to=LastOne(moves);
        *move++=temp|(to<<6)|((-PcOnSq(to))<<15);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce bishop moves by cycling through the       |
|   *_bishop board to locate a [from] square and then      |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
    piecebd=WhiteBishops;
    while (piecebd) {
      from=LastOne(piecebd);
      moves=AttacksBishop(from) & BlackPieces;
      temp=from+(bishop<<12);
      while (moves) {
        to=LastOne(moves);
        *move++=temp|(to<<6)|((-PcOnSq(to))<<15);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce rook moves by cycling through the         |
|   *_rook board to locate a [from] square and then        |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
    piecebd=WhiteRooks;
    while (piecebd) {
      from=LastOne(piecebd);
      moves=AttacksRook(from) & BlackPieces;
      temp=from+(rook<<12);
      while (moves) {
        to=LastOne(moves);
        *move++=temp|(to<<6)|((-PcOnSq(to))<<15);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce queen moves by cycling through the        |
|   *_queen board to locate a [from] square and then       |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
    piecebd=WhiteQueens;
    while (piecebd) {
      from=LastOne(piecebd);
      moves=AttacksQueen(from) & BlackPieces;
      temp=from+(queen<<12);
      while (moves) {
        to=LastOne(moves);
        *move++=temp|(to<<6)|((-PcOnSq(to))<<15);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce king moves by cycling through the         |
|   *_king board to locate a [from] square and then        |
|   cycling through king_attacks[] to locate to squares    |
|   that a king on [from] attacks.                         |
|                                                          |
 ----------------------------------------------------------
*/
    from=WhiteKingSQ;
    moves=king_attacks[from] & BlackPieces;
    temp=from+(king<<12);
    while (moves) {
      to=LastOne(moves);
      *move++=temp|(to<<6)|((-PcOnSq(to))<<15);
      Clear(to,moves);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce pawn moves.  this is done differently due |
|   to inconsistencies in the way a pawn moves when it     |
|   captures as opposed to normal non-capturing moves.     |
|   another exception is capturing enpassant.  the first   |
|   step is to generate all possible pawn promotions.  we  |
|   do this by masking  all pawns but those on the 7th     |
|   rank and then advancing them ahead if the square in    |
|   front is empty.                                        |
|                                                          |
 ----------------------------------------------------------
*/
    promotions=(WhitePawns & rank_mask[RANK7])>>8 & ~Occupied;
    while (promotions) {
      to=LastOne(promotions);
      *move++=(to-8)|(to<<6)|(pawn<<12)|(queen<<18);
      Clear(to,promotions);
    }

    target=BlackPieces | EnPassantTarget(ply);
    pcapturesl=(WhitePawns & mask_left_edge)>>7 & target;
    while (pcapturesl) {
      to=LastOne(pcapturesl);
      if (to < 56) {
        register int cap=(PcOnSq(to)) ? -PcOnSq(to) : pawn;
        *move++=(to-7)|(to<<6)|(pawn<<12)|(cap<<15);
      }
      else 
        *move++=(to-7)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(queen<<18);
      Clear(to,pcapturesl);
    }

    pcapturesr=(WhitePawns & mask_right_edge)>>9 & target;
    while (pcapturesr) {
      to=LastOne(pcapturesr);
      if (to < 56) {
        register int cap=(PcOnSq(to)) ? -PcOnSq(to) : pawn;
        *move++=(to-9)|(to<<6)|(pawn<<12)|(cap<<15);
      }
      else 
        *move++=(to-9)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(queen<<18);
      Clear(to,pcapturesr);
    }
  }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce knight moves by cycling through the       |
|   *_knight board to locate a [from] square and then      |
|   cycling through knight_attacks[] to locate to squares  |
|   that a knight on [from] attacks.                       |
|                                                          |
 ----------------------------------------------------------
*/
  else {
    piecebd=BlackKnights;
    while (piecebd) {
      from=FirstOne(piecebd);
      moves=knight_attacks[from] & WhitePieces;
      temp=from+(knight<<12);
      while (moves) {
        to=FirstOne(moves);
        *move++=temp|(to<<6)|(PcOnSq(to)<<15);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce bishop moves by cycling through the       |
|   *_bishop board to locate a [from] square and then      |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
    piecebd=BlackBishops;
    while (piecebd) {
      from=FirstOne(piecebd);
      moves=AttacksBishop(from) & WhitePieces;
      temp=from+(bishop<<12);
      while (moves) {
        to=FirstOne(moves);
        *move++=temp|(to<<6)|(PcOnSq(to)<<15);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce rook moves by cycling through the         |
|   *_rook board to locate a [from] square and then        |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
    piecebd=BlackRooks;
    while (piecebd) {
      from=FirstOne(piecebd);
      moves=AttacksRook(from) & WhitePieces;
      temp=from+(rook<<12);
      while (moves) {
        to=FirstOne(moves);
        *move++=temp|(to<<6)|(PcOnSq(to)<<15);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce queen moves by cycling through the        |
|   *_queen board to locate a [from] square and then       |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
    piecebd=BlackQueens;
    while (piecebd) {
      from=FirstOne(piecebd);
      moves=AttacksQueen(from) & WhitePieces;
      temp=from+(queen<<12);
      while (moves) {
        to=FirstOne(moves);
        *move++=temp|(to<<6)|(PcOnSq(to)<<15);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce king moves by cycling through the         |
|   *_king board to locate a [from] square and then        |
|   cycling through king_attacks[] to locate to squares    |
|   that a king on [from] attacks.                         |
|                                                          |
 ----------------------------------------------------------
*/
    from=BlackKingSQ;
    moves=king_attacks[from] & WhitePieces;
    temp=from+(king<<12);
    while (moves) {
      to=FirstOne(moves);
      *move++=temp|(to<<6)|(PcOnSq(to)<<15);
      Clear(to,moves);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce pawn moves.  this is done differently due |
|   to inconsistencies in the way a pawn moves when it     |
|   captures as opposed to normal non-capturing moves.     |
|   another exception is capturing enpassant.  the first   |
|   step is to generate all possible pawn promotions.  we  |
|   do this by masking  all pawns but those on the 7th     |
|   rank and then advancing them ahead if the square in    |
|   front is empty.                                        |
|                                                          |
 ----------------------------------------------------------
*/
    promotions=(BlackPawns & rank_mask[RANK2])<<8 & ~Occupied;
    while (promotions) {
      to=FirstOne(promotions);
      *move++=(to+8)|(to<<6)|(pawn<<12)|(queen<<18);
      Clear(to,promotions);
    }

    target=WhitePieces | EnPassantTarget(ply);
    pcapturesl=(BlackPawns & mask_left_edge)<<9 & target;
    while (pcapturesl) {
      to=FirstOne(pcapturesl);
      if (to > 7) {
        register int cap=(PcOnSq(to)) ? PcOnSq(to) : pawn;
        *move++=(to+9)|(to<<6)|(pawn<<12)|(cap<<15);
      }
      else
        *move++=(to+9)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(queen<<18);
      Clear(to,pcapturesl);
    }

    pcapturesr=(BlackPawns & mask_right_edge)<<7 & target;
    while (pcapturesr) {
      to=FirstOne(pcapturesr);
      if (to > 7) {
        register int cap=(PcOnSq(to)) ? PcOnSq(to) : pawn;
        *move++=(to+7)|(to<<6)|(pawn<<12)|(cap<<15);
      }
      else
        *move++=(to+7)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(queen<<18);
      Clear(to,pcapturesr);
    }
  }
  return(move);
}

/* modified 08/23/99 */
/*
********************************************************************************
*                                                                              *
*   GenerateCheckEvasions() is used to generate moves when the king is in      *
*   check.                                                                     *
*                                                                              *
*   three types of check-evasion moves are generated:                          *
*                                                                              *
*   (1) generate king moves to squares that are not attacked by the opponent's *
*   pieces.  this includes capture and non-capture moves.                      *
*                                                                              *
*   (2) generate interpositions along the rank/file that the checking attack   *
*   is coming along (assuming (a) only one piece is checking the king, and     *
*   (b) the checking piece is a sliding piece [bishop, rook, queen]).          *
*                                                                              *
*   (3) generate capture moves, but only to the square(s) that are giving      *
*   check.  captures are a special case.  if there is one checking piece, then *
*   capturing it by any piece is tried.  if there are two pieces checking the  *
*   king, then the only legal capture to try is for the king to capture one of *
*   the checking pieces that is on an un-attacked square.                      *
*                                                                              *
********************************************************************************
*/
int* GenerateCheckEvasions(TREE *tree, int ply, int wtm, int *move) {
  register BITBOARD target, targetc, targetp, piecebd, moves;
  register BITBOARD padvances1, padvances2, pcapturesl, pcapturesr;
  register BITBOARD padvances1_all, empty, checksqs;
  register int from, to, temp;
  register int king_square, checkers, checking_square;
  register int check_direction1=0, check_direction2=0;

/*
 ----------------------------------------------------------
|                                                          |
|   first, determine how many pieces are attacking the     |
|   king and where they are, so we can figure out how to   |
|   legally get out of check.                              |
|                                                          |
 ----------------------------------------------------------
*/
  if (wtm) {
    king_square=WhiteKingSQ;
    checksqs=AttacksTo(tree,king_square) & BlackPieces;
    checkers=PopCnt(checksqs);
    if (checkers == 1) {
      checking_square=FirstOne(AttacksTo(tree,king_square) & BlackPieces);
      if (PcOnSq(checking_square) != -pawn)
        check_direction1=directions[checking_square][king_square];
      target=InterposeSquares(check_direction1,king_square,checking_square);
      target=target | (AttacksTo(tree,king_square) & BlackPieces);
      target=target | BlackKing;
    }
    else {
      target=BlackKing;
      checking_square=FirstOne(checksqs);
      if (PcOnSq(checking_square) != -pawn)
        check_direction1=directions[checking_square][king_square];
      Clear(checking_square,checksqs);
      checking_square=FirstOne(checksqs);
      if (PcOnSq(checking_square) != -pawn)
        check_direction2=directions[checking_square][king_square];
    }
/*
 ----------------------------------------------------------
|                                                          |
|   the next step is to produce the set of valid           |
|   destination squares.  for king moves, this is simply   |
|   the set of squares that are not attacked by enemy      |
|   pieces (if there are any such squares.)                |
|                                                          |
|   then, if the checking piece is not a knight, we need   |
|   to know the checking direction so that we can either   |
|   move the king "off" of that direction, or else "block" |
|   that direction.                                        |
|                                                          |
|   first produce king moves by cycling through the        |
|   *_king board to locate a [from] square and then        |
|   cycling through attacks_to[] to locate to squares      |
|   that the king on [from] attacks.                       |
|                                                          |
 ----------------------------------------------------------
*/
    from=king_square;
    moves=king_attacks[from] & ~WhitePieces;
    temp=from+(king<<12);
    while (moves) {
      to=LastOne(moves);
      if (!Attacked(tree,to,0) && (directions[from][to] != check_direction1) &&
                                 (directions[from][to] != check_direction2))
        *move++=temp|(to<<6)|((-PcOnSq(to))<<15);
      Clear(to,moves);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce knight moves by cycling through the       |
|   *_knight board to locate a [from] square and then      |
|   cycling through knight_attacks[] to locate to squares  |
|   that a knight on [from] attacks.                       |
|                                                          |
 ----------------------------------------------------------
*/
    if (checkers == 1) {
      piecebd=WhiteKnights;
      while (piecebd) {
        from=LastOne(piecebd);
        if (!PinnedOnKing(tree,wtm,from)) {
          moves=knight_attacks[from] & target;
          temp=from+(knight<<12);
          while (moves) {
            to=LastOne(moves);
            *move++=temp|(to<<6)|((-PcOnSq(to))<<15);
            Clear(to,moves);
          }
        }
        Clear(from,piecebd);
      }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce bishop moves by cycling through the       |
|   *_bishop board to locate a [from] square and then      |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
      piecebd=WhiteBishops;
      while (piecebd) {
        from=LastOne(piecebd);
        if (!PinnedOnKing(tree,wtm,from)) {
          moves=AttacksBishop(from) & target;
          temp=from+(bishop<<12);
          while (moves) {
            to=LastOne(moves);
            *move++=temp|(to<<6)|((-PcOnSq(to))<<15);
            Clear(to,moves);
          }
        }
        Clear(from,piecebd);
      }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce rook moves by cycling through the         |
|   *_rook board to locate a [from] square and then        |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
      piecebd=WhiteRooks;
      while (piecebd) {
        from=LastOne(piecebd);
        if (!PinnedOnKing(tree,wtm,from)) {
          moves=AttacksRook(from) & target;
          temp=from+(rook<<12);
          while (moves) {
            to=LastOne(moves);
            *move++=temp|(to<<6)|((-PcOnSq(to))<<15);
            Clear(to,moves);
          }
        }
        Clear(from,piecebd);
      }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce queen moves by cycling through the        |
|   *_queen board to locate a [from] square and then       |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
      piecebd=WhiteQueens;
      while (piecebd) {
        from=LastOne(piecebd);
        if (!PinnedOnKing(tree,wtm,from)) {
          moves=AttacksQueen(from) & target;
          temp=from+(queen<<12);
          while (moves) {
            to=LastOne(moves);
            *move++=temp|(to<<6)|((-PcOnSq(to))<<15);
            Clear(to,moves);
          }
        }
        Clear(from,piecebd);
      }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce pawn moves.  this is done differently due |
|   to inconsistencies in the way a pawn moves when it     |
|   captures as opposed to normal non-capturing moves.     |
|   another exception is capturing enpassant.  the first   |
|   step is to generate all possible pawn moves.  we do    |
|   this in 2 operations:  (1) shift the pawns forward one |
|   rank then and with empty squares;  (2) shift the pawns |
|   forward two ranks and then and with empty squares.     |
|                                                          |
 ----------------------------------------------------------
*/
      empty=~Occupied;
      targetp=target & empty;
      padvances1=WhitePawns>>8 & targetp;
      padvances1_all=WhitePawns>>8& empty;
      padvances2=(padvances1_all & (mask_8>>16))>>8 & targetp;
/*
 ----------------------------------------------------------
|                                                          |
|   now that we got 'em, we simply enumerate the to        |
|   squares as before, but in four steps since we have     |
|   four sets of potential moves.                          |
|                                                          |
 ----------------------------------------------------------
*/
      while (padvances2) {
        to=LastOne(padvances2);
        if (!PinnedOnKing(tree,wtm,to-16)) *move++=(to-16)|(to<<6)|(pawn<<12);
        Clear(to,padvances2);
      }
      while (padvances1) {
        to=LastOne(padvances1);
        if (!PinnedOnKing(tree,wtm,to-8)) {
          if (to < 56) *move++=(to-8)|(to<<6)|(pawn<<12);
          else {
            *move++=(to-8)|(to<<6)|(pawn<<12)|(queen<<18);
            *move++=(to-8)|(to<<6)|(pawn<<12)|(rook<<18);
            *move++=(to-8)|(to<<6)|(pawn<<12)|(bishop<<18);
            *move++=(to-8)|(to<<6)|(pawn<<12)|(knight<<18);
          }
        }
        Clear(to,padvances1);
      }

      targetc=BlackPieces | EnPassantTarget(ply);
      targetc=targetc & target;
      if (BlackPawns & target & EnPassantTarget(ply)<<8)
        targetc=targetc | EnPassantTarget(ply);
      pcapturesl=(WhitePawns & mask_left_edge)>>7 & targetc;
      pcapturesr=(WhitePawns & mask_right_edge)>>9 & targetc;
      while (pcapturesl) {
        to=LastOne(pcapturesl);
        if (!PinnedOnKing(tree,wtm,to-7)) {
          if (to < 56) {
            register int cap=(PcOnSq(to)) ? -PcOnSq(to) : pawn;
            *move++=(to-7)|(to<<6)|(pawn<<12)|(cap<<15);
          }
          else {
            *move++=(to-7)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(queen<<18);
            *move++=(to-7)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(rook<<18);
            *move++=(to-7)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(bishop<<18);
            *move++=(to-7)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(knight<<18);
          }
        }
        Clear(to,pcapturesl);
      }
      while (pcapturesr) {
        to=LastOne(pcapturesr);
        if (!PinnedOnKing(tree,wtm,to-9)) {
          if (to < 56) {
            register int cap=(PcOnSq(to)) ? -PcOnSq(to) : pawn;
            *move++=(to-9)|(to<<6)|(pawn<<12)|(cap<<15);
          }
          else {
            *move++=(to-9)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(queen<<18);
            *move++=(to-9)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(rook<<18);
            *move++=(to-9)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(bishop<<18);
            *move++=(to-9)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(knight<<18);
          }
        }
        Clear(to,pcapturesr);
      }
    }
  }
/*
 ----------------------------------------------------------
|                                                          |
|   first, determine how many pieces are attacking the     |
|   king and where they are, so we can figure out how to   |
|   legally get out of check.                              |
|                                                          |
 ----------------------------------------------------------
*/
  else {
    king_square=BlackKingSQ;
    checksqs=AttacksTo(tree,king_square) & WhitePieces;
    checkers=PopCnt(checksqs);
    if (checkers == 1) {
      checking_square=FirstOne(AttacksTo(tree,king_square) & WhitePieces);
      if (PcOnSq(checking_square) != pawn)
        check_direction1=directions[checking_square][king_square];
      target=InterposeSquares(check_direction1,king_square,checking_square);
      target=target | (AttacksTo(tree,king_square) & WhitePieces);
      target=target | WhiteKing;
    }
    else {
      target=WhiteKing;
      checking_square=FirstOne(checksqs);
      if (PcOnSq(checking_square) != pawn)
        check_direction1=directions[checking_square][king_square];
      Clear(checking_square,checksqs);
      checking_square=FirstOne(checksqs);
      if (PcOnSq(checking_square) != pawn)
        check_direction2=directions[checking_square][king_square];
    }
/*
 ----------------------------------------------------------
|                                                          |
|   the first step is to produce the set of valid          |
|   destination squares.  for king moves, this is simply   |
|   the set of squares that are not attacked by enemy      |
|   pieces (if there are any such squares.)                |
|                                                          |
|   then, if the checking piece is not a knight, we need   |
|   to know the checking direction so that we can either   |
|   move the king "off" of that direction, or else "block" |
|   that direction.                                        |
|                                                          |
|   first produce king moves by cycling through the        |
|   *_king board to locate a [from] square and then        |
|   cycling through attacks_to[] to locate to squares      |
|   that the king on [from] attacks.                       |
|                                                          |
 ----------------------------------------------------------
*/
    from=king_square;
    moves=king_attacks[from] & ~BlackPieces;
    temp=from+(king<<12);
    while (moves) {
      to=FirstOne(moves);
      if (!Attacked(tree,to,1) && (directions[from][to] != check_direction1) &&
                                 (directions[from][to] != check_direction2))
        *move++=temp|(to<<6)|(PcOnSq(to)<<15);
      Clear(to,moves);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce knight moves by cycling through the       |
|   *_knight board to locate a [from] square and then      |
|   cycling through knight_attacks[] to locate to squares  |
|   that a knight on [from] attacks.                       |
|                                                          |
 ----------------------------------------------------------
*/
    if (checkers == 1) {
      piecebd=BlackKnights;
      while (piecebd) {
        from=FirstOne(piecebd);
        if (!PinnedOnKing(tree,wtm,from)) {
          moves=knight_attacks[from] & target;
          temp=from+(knight<<12);
          while (moves) {
            to=FirstOne(moves);
            *move++=temp|(to<<6)|(PcOnSq(to)<<15);
            Clear(to,moves);
          }
        }
        Clear(from,piecebd);
      }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce bishop moves by cycling through the       |
|   *_bishop board to locate a [from] square and then      |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
      piecebd=BlackBishops;
      while (piecebd) {
        from=FirstOne(piecebd);
        if (!PinnedOnKing(tree,wtm,from)) {
          moves=AttacksBishop(from) & target;
          temp=from+(bishop<<12);
          while (moves) {
            to=FirstOne(moves);
            *move++=temp|(to<<6)|(PcOnSq(to)<<15);
            Clear(to,moves);
          }
        }
        Clear(from,piecebd);
      }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce rook moves by cycling through the         |
|   *_rook board to locate a [from] square and then        |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
      piecebd=BlackRooks;
      while (piecebd) {
        from=FirstOne(piecebd);
        if (!PinnedOnKing(tree,wtm,from)) {
          moves=AttacksRook(from) & target;
          temp=from+(rook<<12);
          while (moves) {
            to=FirstOne(moves);
            *move++=temp|(to<<6)|(PcOnSq(to)<<15);
            Clear(to,moves);
          }
        }
        Clear(from,piecebd);
      }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce queen moves by cycling through the        |
|   *_queen board to locate a [from] square and then       |
|                                                          |
 ----------------------------------------------------------
*/
      piecebd=BlackQueens;
      while (piecebd) {
        from=FirstOne(piecebd);
        if (!PinnedOnKing(tree,wtm,from)) {
          moves=AttacksQueen(from) & target;
          temp=from+(queen<<12);
          while (moves) {
            to=FirstOne(moves);
            *move++=temp|(to<<6)|(PcOnSq(to)<<15);
            Clear(to,moves);
          }
        }
        Clear(from,piecebd);
      }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce pawn moves.  this is done differently due |
|   to inconsistencies in the way a pawn moves when it     |
|   captures as opposed to normal non-capturing moves.     |
|   another exception is capturing enpassant.  the first   |
|   step is to generate all possible pawn moves.  we do    |
|   this in 4 operations:  (1) shift the pawns forward one |
|   rank then and with empty squares;  (2) shift the pawns |
|   forward two ranks and then and with empty squares;     |
|   (3) remove the a-pawn(s) then shift the pawns          |
|   diagonally left then and with enemy occupied squares;  |
|   (4) remove the h-pawn(s) then shift the pawns          |
|   diagonally right then and with enemy occupied squares; |
|   note that enemy occupied squares includes the special  |
|   case of the enpassant target square also.              |
|                                                          |
 ----------------------------------------------------------
*/
      empty=~Occupied;
      targetp=target & empty;
      padvances1=BlackPawns<<8 & targetp;
      padvances1_all=BlackPawns<<8 & empty;
      padvances2=(padvances1_all & (mask_120<<16))<<8 & targetp;
/*
 ----------------------------------------------------------
|                                                          |
|   now that we got 'em, we simply enumerate the to        |
|   squares as before, but in four steps since we have     |
|   four sets of potential moves.                          |
|                                                          |
 ----------------------------------------------------------
*/
      while (padvances2) {
        to=FirstOne(padvances2);
        if (!PinnedOnKing(tree,wtm,to+16)) *move++=(to+16)|(to<<6)|(pawn<<12);
        Clear(to,padvances2);
      }
      while (padvances1) {
        to=FirstOne(padvances1);
        if (!PinnedOnKing(tree,wtm,to+8)) {
          if (to > 7) *move++=(to+8)|(to<<6)|(pawn<<12);
          else {
            *move++=(to+8)|(to<<6)|(pawn<<12)|(queen<<18);
            *move++=(to+8)|(to<<6)|(pawn<<12)|(rook<<18);
            *move++=(to+8)|(to<<6)|(pawn<<12)|(bishop<<18);
            *move++=(to+8)|(to<<6)|(pawn<<12)|(knight<<18);
          }
        }
        Clear(to,padvances1);
      }

      targetc=WhitePieces | EnPassantTarget(ply);
      targetc=targetc & target;
      if (WhitePawns & target & EnPassantTarget(ply)>>8)
        targetc=targetc | EnPassantTarget(ply);
      pcapturesl=(BlackPawns & mask_left_edge)<<9 & targetc;
      pcapturesr=(BlackPawns & mask_right_edge)<<7 & targetc;
      while (pcapturesl) {
        to=FirstOne(pcapturesl);
        if (!PinnedOnKing(tree,wtm,to+9)) {
          if (to > 7) {
            register int cap=(PcOnSq(to)) ? PcOnSq(to) : pawn;
            *move++=(to+9)|(to<<6)|(pawn<<12)|(cap<<15);
          }
          else {
            *move++=(to+9)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(queen<<18);
            *move++=(to+9)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(rook<<18);
            *move++=(to+9)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(bishop<<18);
            *move++=(to+9)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(knight<<18);
          }
        }
        Clear(to,pcapturesl);
      }
      while (pcapturesr) {
        to=FirstOne(pcapturesr);
        if (!PinnedOnKing(tree,wtm,to+7)) {
          if (to > 7) {
            register int cap=(PcOnSq(to)) ? PcOnSq(to) : pawn;
            *move++=(to+7)|(to<<6)|(pawn<<12)|(cap<<15);
          }
          else {
            *move++=(to+7)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(queen<<18);
            *move++=(to+7)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(rook<<18);
            *move++=(to+7)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(bishop<<18);
            *move++=(to+7)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(knight<<18);
          }
        }
        Clear(to,pcapturesr);
      }
    }
  }
  return(move);
}

/* modified 03/11/97 */
/*
********************************************************************************
*                                                                              *
*   GenerateNonCaptures() is used to generate non-capture moves from the       *
*   current position.                                                          *
*                                                                              *
*   once the valid destination squares are known, we have to locate a friendly *
*   piece to get a attacks_to[] entry.  we then produce the moves for this     *
*   piece by using the source square as [from] and enumerating each square it  *
*   attacks into [to].                                                         *
*                                                                              *
*   pawns are handled differently.  regular pawn moves are produced by         *
*   shifting the pawn bitmap 8 bits "forward" and anding this with the         *
*   complement of the occupied squares bitmap  double advances are then        *
*   produced by anding the pawn bitmap with a mask containing 1's on the       *
*   second rank, shifting this 16 bits "forward" and then anding this with     *
*   the complement of the occupied squares bitmap as before.  if [to]          *
*   reaches the 8th rank, we produce a set of four moves, promoting the pawn   *
*   to knight, bishop, rook and queen.                                         *
*                                                                              *
********************************************************************************
*/
int* GenerateNonCaptures(TREE *tree, int ply, int wtm, int *move) {
  register BITBOARD target, piecebd, moves;
  register BITBOARD  padvances1, padvances2, pcapturesl, pcapturesr;
  register int from, to, temp;

  if (wtm) {
/*
 ----------------------------------------------------------
|                                                          |
|   first, produce castling moves if it is legal.          |
|                                                          |
 ----------------------------------------------------------
*/
    if (WhiteCastle(ply) > 0) {
      if ((WhiteCastle(ply)&1) && !(Occupied & mask_white_OO) &&
          !Attacked(tree,E1,0) && !Attacked(tree,F1,0) && !Attacked(tree,G1,0)) {
        *move++=12676;
      }
      if ((WhiteCastle(ply)&2) && !(Occupied & mask_white_OOO) &&
          !Attacked(tree,C1,0) && !Attacked(tree,D1,0) && !Attacked(tree,E1,0)) {
        *move++=12420;
      }
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce knight moves by cycling through the       |
|   *_knight board to locate a [from] square and then      |
|   cycling through knight_attacks[] to locate to squares  |
|   that a knight on [from] attacks.                       |
|                                                          |
 ----------------------------------------------------------
*/
    target=~Occupied;
    piecebd=WhiteKnights;
    while (piecebd) {
      from=LastOne(piecebd);
      moves=knight_attacks[from] & target;
      temp=from+(knight<<12);
      while (moves) {
        to=LastOne(moves);
        *move++=temp|(to<<6);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce bishop moves by cycling through the       |
|   *_bishop board to locate a [from] square and then      |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
    piecebd=WhiteBishops;
    while (piecebd) {
      from=LastOne(piecebd);
      moves=AttacksBishop(from) & target;
      temp=from+(bishop<<12);
      while (moves) {
        to=LastOne(moves);
        *move++=temp|(to<<6);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce rook moves by cycling through the         |
|   *_rook board to locate a [from] square and then        |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
    piecebd=WhiteRooks;
    while (piecebd) {
      from=LastOne(piecebd);
      moves=AttacksRook(from) & target;
      temp=from+(rook<<12);
      while (moves) {
        to=LastOne(moves);
        *move++=temp|(to<<6);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce queen moves by cycling through the        |
|   *_queen board to locate a [from] square and then       |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
    piecebd=WhiteQueens;
    while (piecebd) {
      from=LastOne(piecebd);
      moves=AttacksQueen(from) & target;
      temp=from+(queen<<12);
      while (moves) {
        to=LastOne(moves);
        *move++=temp|(to<<6);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce king moves by cycling through the         |
|   *_king board to locate a [from] square and then        |
|   cycling through king_attacks[] to locate to squares    |
|   that a king on [from] attacks.                         |
|                                                          |
 ----------------------------------------------------------
*/
    from=WhiteKingSQ;
    moves=king_attacks[from] & target;
    temp=from+(king<<12);
    while (moves) {
      to=LastOne(moves);
      *move++=temp|(to<<6);
      Clear(to,moves);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce pawn moves.  this is done differently due |
|   to inconsistencies in the way a pawn moves when it     |
|   captures as opposed to normal non-capturing moves.     |
|   first we generate all possible pawn moves.  we do      |
|   this in 4 operations:  (1) shift the pawns forward one |
|   rank then and with empty squares;  (2) shift the pawns |
|   forward two ranks and then and with empty squares;     |
|   (3) remove the a-pawn(s) then shift the pawns          |
|   diagonally left then and with enemy occupied squares;  |
|   (4) remove the h-pawn(s) then shift the pawns          |
|   diagonally right then and with enemy occupied squares. |
|   note that the only captures produced are under-        |
|   promotions, because the rest were done in GenCap.      |
|                                                          |
 ----------------------------------------------------------
*/
    padvances1=WhitePawns>>8 & target;
    padvances2=(padvances1 & mask_advance_2_w)>>8 & target;
/*
 ----------------------------------------------------------
|                                                          |
|   now that we got 'em, we simply enumerate the to        |
|   squares as before, but in four steps since we have     |
|   four sets of potential moves.                          |
|                                                          |
 ----------------------------------------------------------
*/
    while (padvances2) {
      to=LastOne(padvances2);
      *move++=(to-16)|(to<<6)|(pawn<<12);
      Clear(to,padvances2);
    }

    while (padvances1) {
      to=LastOne(padvances1);
      if (to < 56) *move++=(to-8)|(to<<6)|(pawn<<12);
      else {
        *move++=(to-8)|(to<<6)|(pawn<<12)|(rook<<18);
        *move++=(to-8)|(to<<6)|(pawn<<12)|(bishop<<18);
        *move++=(to-8)|(to<<6)|(pawn<<12)|(knight<<18);
      }
      Clear(to,padvances1);
    }

    target=BlackPieces & rank_mask[RANK8];
    pcapturesl=(WhitePawns & mask_left_edge)>>7 & target;
    pcapturesr=(WhitePawns & mask_right_edge)>>9 & target;
    while (pcapturesl) {
      to=LastOne(pcapturesl);
      *move++=(to-7)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(rook<<18);
      *move++=(to-7)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(bishop<<18);
      *move++=(to-7)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(knight<<18);
      Clear(to,pcapturesl);
    }
    while (pcapturesr) {
      to=LastOne(pcapturesr);
      *move++=(to-9)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(rook<<18);
      *move++=(to-9)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(bishop<<18);
      *move++=(to-9)|(to<<6)|(pawn<<12)|((-PcOnSq(to))<<15)|(knight<<18);
      Clear(to,pcapturesr);
    }
  }
/*
 ----------------------------------------------------------
|                                                          |
|   first, produce castling moves if it is legal.          |
|                                                          |
 ----------------------------------------------------------
*/
  else {
    if (BlackCastle(ply) > 0) {
      if ((BlackCastle(ply)&1) && !(Occupied & mask_black_OO) &&
          !Attacked(tree,E8,1) && !Attacked(tree,F8,1) && !Attacked(tree,G8,1)) {
        *move++=16316;
      }
      if ((BlackCastle(ply)&2) && !(Occupied & mask_black_OOO) &&
          !Attacked(tree,C8,1) && !Attacked(tree,D8,1) && !Attacked(tree,E8,1)) {
        *move++=16060;
      }
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce knight moves by cycling through the       |
|   *_knight board to locate a [from] square and then      |
|   cycling through knight_attacks[] to locate to squares  |
|   that a knight on [from] attacks.                       |
|                                                          |
 ----------------------------------------------------------
*/
    target=~Occupied;
    piecebd=BlackKnights;
    while (piecebd) {
      from=FirstOne(piecebd);
      moves=knight_attacks[from] & target;
      temp=from+(knight<<12);
      while (moves) {
        to=FirstOne(moves);
        *move++=temp|(to<<6);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce bishop moves by cycling through the       |
|   *_bishop board to locate a [from] square and then      |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
    piecebd=BlackBishops;
    while (piecebd) {
      from=FirstOne(piecebd);
      moves=AttacksBishop(from) & target;
      temp=from+(bishop<<12);
      while (moves) {
        to=FirstOne(moves);
        *move++=temp|(to<<6);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce rook moves by cycling through the         |
|   *_rook board to locate a [from] square and then        |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
    piecebd=BlackRooks;
    while (piecebd) {
      from=FirstOne(piecebd);
      moves=AttacksRook(from) & target;
      temp=from+(rook<<12);
      while (moves) {
        to=FirstOne(moves);
        *move++=temp|(to<<6);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce queen moves by cycling through the        |
|   *_queen board to locate a [from] square and then       |
|   generate the AttacksFrom() bitmap which supplies the   |
|   list of valid <to> squares.                            |
|                                                          |
 ----------------------------------------------------------
*/
    piecebd=BlackQueens;
    while (piecebd) {
      from=FirstOne(piecebd);
      moves=AttacksQueen(from) & target;
      temp=from+(queen<<12);
      while (moves) {
        to=FirstOne(moves);
        *move++=temp|(to<<6);
        Clear(to,moves);
      }
      Clear(from,piecebd);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce king moves by cycling through the         |
|   *_king board to locate a [from] square and then        |
|   cycling through king_attacks[] to locate to squares    |
|   that a king on [from] attacks.                         |
|                                                          |
 ----------------------------------------------------------
*/
    from=BlackKingSQ;
    moves=king_attacks[from] & target;
    temp=from+(king<<12);
    while (moves) {
      to=FirstOne(moves);
      *move++=temp|(to<<6);
      Clear(to,moves);
    }
/*
 ----------------------------------------------------------
|                                                          |
|   now, produce pawn moves.  this is done differently due |
|   to inconsistencies in the way a pawn moves when it     |
|   captures as opposed to normal non-capturing moves.     |
|   first we generate all possible pawn moves.  we do      |
|   this in 4 operations:  (1) shift the pawns forward one |
|   rank then and with empty squares;  (2) shift the pawns |
|   forward two ranks and then and with empty squares;     |
|   (3) remove the a-pawn(s) then shift the pawns          |
|   diagonally left then and with enemy occupied squares;  |
|   (4) remove the h-pawn(s) then shift the pawns          |
|   diagonally right then and with enemy occupied squares. |
|   note that the only captures produced are under-        |
|   promotions, because the rest were done in GenCap.      |
|                                                          |
 ----------------------------------------------------------
*/
    padvances1=BlackPawns<<8 & target;
    padvances2=(padvances1 & mask_advance_2_b)<<8 & target;
/*
 ----------------------------------------------------------
|                                                          |
|   now that we got 'em, we simply enumerate the to        |
|   squares as before, but in four steps since we have     |
|   four sets of potential moves.                          |
|                                                          |
 ----------------------------------------------------------
*/
    while (padvances2) {
      to=FirstOne(padvances2);
      *move++=(to+16)|(to<<6)|(pawn<<12);
      Clear(to,padvances2);
    }
    while (padvances1) {
      to=FirstOne(padvances1);
      if (to > 7) *move++=(to+8)|(to<<6)|(pawn<<12);
      else {
        *move++=(to+8)|(to<<6)|(pawn<<12)|(rook<<18);
        *move++=(to+8)|(to<<6)|(pawn<<12)|(bishop<<18);
        *move++=(to+8)|(to<<6)|(pawn<<12)|(knight<<18);
      }
      Clear(to,padvances1);
    }
    target=WhitePieces & rank_mask[RANK1];
    pcapturesl=(BlackPawns & mask_left_edge)<<9 & target;
    pcapturesr=(BlackPawns & mask_right_edge)<<7 & target;
    while (pcapturesl) {
      to=FirstOne(pcapturesl);
      *move++=(to+9)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(rook<<18);
      *move++=(to+9)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(bishop<<18);
      *move++=(to+9)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(knight<<18);
      Clear(to,pcapturesl);
    }
    while (pcapturesr) {
      to=FirstOne(pcapturesr);
      *move++=(to+7)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(rook<<18);
      *move++=(to+7)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(bishop<<18);
      *move++=(to+7)|(to<<6)|(pawn<<12)|(PcOnSq(to)<<15)|(knight<<18);
      Clear(to,pcapturesr);
    }
  }
  return(move);
}