/*
* Add an available move for the player to the list of moves, the move is specifically created for peons,
* as it may contain promotions.
* - Move is expected to be valid in terms of piece type constraints (e.g: a peon can only move to 3 possible squares).
* - Additional validation will be done in this function (moves that result in a check status for the current player are
* illegal).
* --> If the move is legal, it is added to the list of possibleMoves. Otherwise nothing happens.
* Input:
* board ~ The chess game board.
* possibleMoves ~ A list of possible moves by the current player, we aggregate it as we check
* possible eat / position change moves.
* isMovesForBlackPlayer ~ True if current player is black. False if white.
* startPos ~ Where the piece is currently located.
* targetX, targetY ~ Coordinates of where the piece will move to.
* kingPos ~ Current position of the current player's king (following the execution of the move).
*/
void addPeonMove(char board[BOARD_SIZE][BOARD_SIZE], LinkedList* possibleMoves, bool isMovesForBlackPlayer,
Position* startPos, int targetX, int targetY, Position* kingPos)
{
bool isMoveAdded = addPossibleMove(board, possibleMoves, isMovesForBlackPlayer, startPos, targetX, targetY, kingPos);
if (g_memError)
return;
if (!isMoveAdded)
return;
// If the pawn reaches the edge, the moves become promotion moves.
if (isSquareOnOppositeEdge(isMovesForBlackPlayer, targetX))
{
char bishop = isMovesForBlackPlayer ? BLACK_B : WHITE_B;
char rook = isMovesForBlackPlayer ? BLACK_R : BLACK_R;
char knight = isMovesForBlackPlayer ? BLACK_N : WHITE_N;
char queen = isMovesForBlackPlayer ? BLACK_Q : WHITE_Q;
((Move*)(possibleMoves->tail->data))->promotion = queen; // Update the most recent move to a promotion move.
addPossibleMove(board, possibleMoves, isMovesForBlackPlayer, startPos, targetX, targetY, kingPos);
if (g_memError)
return;
((Move*)(possibleMoves->tail->data))->promotion = rook; // Update the most recent move to a promotion move.
addPossibleMove(board, possibleMoves, isMovesForBlackPlayer, startPos, targetX, targetY, kingPos);
if (g_memError)
return;
((Move*)(possibleMoves->tail->data))->promotion = bishop; // Update the most recent move to a promotion move.
addPossibleMove(board, possibleMoves, isMovesForBlackPlayer, startPos, targetX, targetY, kingPos);
if (g_memError)
return;
((Move*)(possibleMoves->tail->data))->promotion = knight; // Update the most recent move to a promotion move.
}
}
/*
* Checks if a piece can move / eat in the given direction.
* Input:
* board ~ The game board.
* possibleMoves ~ A list of possible moves by the current player, we aggregate it as we check
* possible eat / position change moves.
* isMovesForBlackPlayer ~ True if current player is black. False if white.
* startPos ~ Where the piece is currently located.
* deltaX, deltaY ~ The direction the piece advances in.
* kingPos ~ Current position of the current player's king.
*/
void queryDirection(char board[BOARD_SIZE][BOARD_SIZE], LinkedList* possibleMoves,
bool isMovesForBlackPlayer, Position* startPos, int deltaX, int deltaY, Position* kingPos)
{
// First square on the diagonal / row / column
Position currentSquare = { startPos->x + deltaX, startPos->y + deltaY };
// We advance along the direction, advancing by deltaX, Y each iteration.
// We will stop once we no longer hit an empty square.
while (isSquareVacant(board, currentSquare.x, currentSquare.y))
{
addPossibleMove(board, possibleMoves, isMovesForBlackPlayer,startPos, currentSquare.x, currentSquare.y, kingPos);
if (g_memError)
return;
currentSquare.x += deltaX;
currentSquare.y += deltaY;
}
// If the reason we stopped iterating was we encountered an enemy piece, we get an additional move: an eat move.
if (isSquareOccupiedByEnemy(board, isMovesForBlackPlayer, currentSquare.x, currentSquare.y))
{
addPossibleMove(board, possibleMoves, isMovesForBlackPlayer, startPos, currentSquare.x, currentSquare.y, kingPos);
}
}
/*
* Add possible move for a single spot, if that spot is available for moving to or eating an enemy piece.
* Input:
* board ~ The game board.
* possibleMoves ~ A list of possible moves by the current player, we aggregate it as we check
* possible eat / position change moves.
* isMovesForBlackPlayer ~ True if current player is black. False if white.
* startPos ~ Where the piece is currently located.
* deltaX, deltaY ~ How many squares away to move the piece to.
* kingPos ~ Current position of the current player's king.
*/
void querySinglePos(char board[BOARD_SIZE][BOARD_SIZE], LinkedList* possibleMoves,
bool isMovesForBlackPlayer, Position* startPos, int deltaX, int deltaY, Position* kingPos)
{
Position nextSquare = { startPos->x + deltaX, startPos->y + deltaY };
if (isSquareVacant(board, nextSquare.x, nextSquare.y) ||
isSquareOccupiedByEnemy(board, isMovesForBlackPlayer, nextSquare.x, nextSquare.y))
{
Position* kingPosArg;
// When the king moves, we should update the kingPos parameter accordingly
if ((startPos->x == kingPos->x) && (startPos->y == kingPos->y))
kingPosArg = &nextSquare; // The king's updated position is where the king moves to
else
kingPosArg = kingPos; // The current move is not made by a king, the kingPos stays the same
addPossibleMove(board, possibleMoves, isMovesForBlackPlayer, startPos, nextSquare.x, nextSquare.y, kingPosArg);
}
}
void generateMoveList() {
// First, we'll figure out the horizontal moves that are possible
int x, y, i, j;
int start, end;
move *temp;
for (y = 0; y < boardHeight; y++) {
end = -1;
while (end < boardWidth) {
start = -1;
// First, find the first place where we can start a line
for (x = end + 1; x < boardWidth; x++) {
if ((gameBoard[xyToIndex(x, y)] & TOP_LINE) == 0) {
start = x;
break;
}
}
if (start == -1)
break; // No free lines on this line
// Now that we know where to start, we'll find where to end
end = boardWidth; // So if we don't find lines, we have a good endpoint
for (x = start; x < boardWidth; x++) {
if (gameBoard[xyToIndex(x, y)] & TOP_LINE) {
// We found a place with a line! Stop just before it
end = x;
break;
}
}
// Now that we've got that, we create the list of possible lines
for (i = start; i < end; i++) {
for (j = i + 1; j <= end; j++) {
addPossibleMove(i, y, j, y);
}
}
}
}
// We have to handle the last line specially, because we have to check for BOTTOM_LINE, not TOP
end = -1;
y = boardHeight - 1;
while (end < boardWidth) {
start = -1;
// First, find the first place where we can start a line
for (x = end + 1; x < boardWidth; x++) {
if ((gameBoard[xyToIndex(x, y)] & BOTTOM_LINE) == 0) {
start = x;
break;
}
}
if (start == -1)
break; // No free lines on this line
// Now that we know where to start, we'll find where to end
end = boardWidth; // So if we don't find lines, we have a good endpoint
for (x = start; x < boardWidth; x++) {
if (gameBoard[xyToIndex(x, y)] & BOTTOM_LINE) {
// We found a place with a line! Stop just before it
end = x;
break;
}
}
// Now that we've got that, we create the list of possible lines
for (i = start; i < end; i++) {
for (j = i + 1; j <= end; j++) {
addPossibleMove(i, boardHeight, j, boardHeight);
}
}
}
// Now, the same thing, only for virticle lines
for (x = 0; x < boardWidth; x++) {
end = -1;
while (end < boardHeight) {
start = -1;
// First, find the first place where we can start a line
for (y = end + 1; y < boardHeight; y++) {
if ((gameBoard[xyToIndex(x, y)] & LEFT_LINE) == 0) {
start = y;
break;
}
}
if (start == -1)
break; // No free lines on this line
// Now that we know where to start, we'll find where to end
end = boardHeight; // So if we don't find lines, we have a good endpoint
for (y = start; y < boardHeight; y++) {
if (gameBoard[xyToIndex(x, y)] & LEFT_LINE) {
// We found a place with a line! Stop just before it
end = y;
break;
}
}
// Now that we've got that, we create the list of possible lines
for (i = start; i < end; i++) {
for (j = i + 1; j <= end; j++) {
addPossibleMove(x, i, x, j);
}
}
}
}
// We have to handle the last line specially, because we have to check for BOTTOM_LINE, not TOP
end = -1;
x = boardWidth - 1;
while (end < boardHeight) {
start = -1;
// First, find the first place where we can start a line
for (y = end + 1; y < boardHeight; y++) {
if ((gameBoard[xyToIndex(x, y)] & RIGHT_LINE) == 0) {
start = y;
break;
}
}
if (start == -1)
break; // No free lines on this line
// Now that we know where to start, we'll find where to end
end = boardHeight; // So if we don't find lines, we have a good endpoint
for (y = start; y < boardHeight; y++) {
if (gameBoard[xyToIndex(x, y)] & RIGHT_LINE) {
// We found a place with a line! Stop just before it
end = y;
break;
}
}
// Now that we've got that, we create the list of possible lines
for (i = start; i < end; i++) {
for (j = i + 1; j <= end; j++) {
addPossibleMove(boardWidth, i, boardWidth, j);
}
}
}
// That's it, the possible move list is full!
}