Initial commit: basic abstractions, a couple of working flags, piece logic and chess notation are not yet complete

.gitignore

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+.vscode/
+bin/

COPYING

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+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program 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 Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If your software can interact with users remotely through a computer
+network, you should also make sure that it provides a way for users to
+get its source.  For example, if your program is a web application, its
+interface could display a "Source" link that leads users to an archive
+of the code.  There are many ways you could offer source, and different
+solutions will be better for different programs; see section 13 for the
+specific requirements.
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU AGPL, see
+<https://www.gnu.org/licenses/>.

Makefile

@@ -0,0 +1,6 @@
+all:
+	mkdir -p bin
+	gcc -Wall -Werror -static -O2 src/*.c -o bin/chess 
+
+clean:
+	rm -rf bin

README.md

@@ -0,0 +1,26 @@
+# C3hess - Console Chess written in C
+
+## A portable chess game and an engine in one package
+
+
+## About
+
+
+
+## Building
+
+```make```
+
+or
+
+```./make.sh```
+
+or compile yourself, there are no dependencies
+
+
+## Installation
+
+
+## License
+
+AGPLv3

TODO

@@ -0,0 +1,2 @@
+1. Algebraic notation: notation_move_from_string, notation_move_to_string, documentation
+2. Board: board_is_move_legal, add other piece's moves

make.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+
+mkdir -p bin
+gcc -Wall -Werror -static -O2 src/*.c -o bin/chess 

src/algebraic_notation.c

@@ -0,0 +1,335 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include "algebraic_notation.h"
+
+
+// Converts a tile notation to a position on the board
+Position notation_tile_to_position(TileNotation notation) {
+    Position pos;
+    switch (notation.file) {
+        case 'a': {
+            pos.column = 1;            
+            break;
+        }
+        case 'b': {
+            pos.column = 2;            
+            break;
+        }
+        case 'c': {
+            pos.column = 3;            
+            break;
+        }
+        case 'd': {
+            pos.column = 4;            
+            break;
+        }
+        case 'e': {
+            pos.column = 5;            
+            break;
+        }
+        case 'f': {
+            pos.column = 6;            
+            break;
+        }
+        case 'g': {
+            pos.column = 7;            
+            break;
+        }
+        case 'h': {
+            pos.column = 8;            
+            break;
+        }
+        default: {
+            break;
+        }
+    }
+    pos.row = notation.rank;
+
+    return pos;
+}
+
+
+char* notation_tile_to_string(TileNotation tile) {
+    char* notation = (char*) malloc(sizeof(char) * 2);
+    if (!notation) {
+        return NULL;
+    }
+
+    notation[0] = tile.file; // col
+    notation[1] = (char) tile.rank; // row
+
+    return notation;
+}
+
+void notation_tile_to_string_cpy(TileNotation tile, char* dest) {
+    if (!dest) {
+        return;
+    }
+
+    char* notation = notation_tile_to_string(tile);
+    strcpy(dest, notation);
+    free(notation);
+
+    return;
+}
+
+
+TileNotation notation_tile_from_string(const char* tile_string) {
+    if (!tile_string) {
+        return notation_tile_new('a', 1);
+    }
+
+    TileNotation tile;
+    tile.file = tile_string[0];
+    tile.rank = (unsigned int) tile_string[1];
+
+    return tile;
+}
+
+
+TileNotation notation_tile_new(char file, unsigned int rank) {
+    TileNotation tile;
+    tile.file = file;
+    tile.rank = rank;
+
+    return tile;
+}
+
+
+// Converts
+TileNotation notation_tile_from_pos(Position pos) {
+    TileNotation tile;    
+    switch (pos.row) {
+        case 1: {
+            tile.file = 'a';            
+            break;
+        }
+        case 2: {
+            tile.file = 'b';            
+            break;
+        }
+        case 3: {
+            tile.file = 'c';            
+            break;
+        }
+        case 4: {
+            tile.file = 'd';            
+            break;
+        }
+        case 5: {
+            tile.file = 'e';            
+            break;
+        }
+        case 6: {
+            tile.file = 'f';            
+            break;
+        }
+        case 7: {
+            tile.file = 'g';            
+            break;
+        }
+        case 8: {
+            tile.file = 'h';            
+            break;
+        }
+        default: {
+            tile.file = '\0';
+            break;
+        }
+    }
+    tile.rank = pos.column;
+
+    return tile;
+}
+
+
+
+// Returns a piece character. Upper case for white, lower case for black
+char notation_piece_to_char(Piece piece) {
+    switch (piece.type) {
+        case KING: {
+            if (piece.color == WHITE) {
+                return 'K';
+            } else {
+                return 'k';
+            }
+            break;
+        }
+        case ROOK: {
+            if (piece.color == WHITE) {
+                return 'R';
+            } else {
+                return 'r';
+            }
+            break;
+        }
+        case BISHOP: {
+            if (piece.color == WHITE) {
+                return 'B';
+            } else {
+                return 'b';
+            }
+            break;
+        }
+        case KNIGHT: {
+            if (piece.color == WHITE) {
+                return 'N';
+            } else {
+                return 'n';
+            }
+            break;
+        }
+        case PAWN: {
+            if (piece.color == WHITE) {
+                return 'P';
+            } else {
+                return 'p';
+            }
+            break;
+        }
+        case QUEEN: {
+            if (piece.color == WHITE) {
+                return 'Q';
+            } else {
+                return 'q';
+            }
+            break;
+        }
+        default: {
+            return '\0';
+        }
+    };
+}
+
+
+// Returns 1 if character is one of the piece characters, 0 otherwise
+int notation_is_piece_char(char character) {
+    if (
+        character == 'K' || character == 'k' || \
+        character == 'R' || character == 'r' || \
+        character == 'B' || character == 'b' || \
+        character == 'N' || character == 'n' || \
+        character == 'P' || character == 'p' || \
+        character == 'Q' || character == 'q'
+    ) {
+        return 1;
+    }
+
+    return 0;
+}
+
+
+char* notation_move_to_string(MoveNotation move) {
+    char* move_notation = (char*) malloc(sizeof(char) * 10);
+    if (!move_notation) {
+        return NULL;
+    }
+
+    // if (move.move_type == MOVE) {
+
+    // }
+
+    switch (move.move_type) {
+        case MOVE: {
+            move_notation[0] = notation_piece_to_char(move.piece);
+            notation_tile_to_string_cpy(move.target, &move_notation[1]);
+            break;
+        }
+
+        case CHECK: {
+            move_notation[0] = notation_piece_to_char(move.piece);
+            notation_tile_to_string_cpy(move.target, &move_notation[1]);
+            move_notation[3] = '+';
+            break;
+        }
+
+        case CAPTURE: {
+            move_notation[0] = notation_piece_to_char(move.piece);
+            move_notation[1] = 'x';
+            notation_tile_to_string_cpy(move.target, &move_notation[2]);
+            break;
+        }
+
+        case CHECK & CAPTURE: {
+            move_notation[0] = notation_piece_to_char(move.piece);
+            move_notation[1] = 'x';
+            notation_tile_to_string_cpy(move.target, &move_notation[2]);
+            move_notation[4] = '+';
+            break;
+        }
+
+        case SHORTCASTLE: {
+            move_notation = strcpy(move_notation, "0-0");
+            break;
+        }
+
+        // case SHORTCASTLE&CHECK: {
+
+        // }
+
+        case LONGCASTLE: {
+            move_notation = strcpy(move_notation, "0-0-0");
+            break;
+        }
+
+        default: {
+            free(move_notation);
+            return NULL;
+        }
+    }
+
+    return move_notation;
+}
+
+
+MoveNotation* notation_move_from_string(const char* move_string) {
+    if (!move_string) {
+        return NULL;
+    }
+
+    MoveNotation* move = (MoveNotation*) malloc(sizeof(MoveNotation) * 1);
+    if (!move) {
+        return NULL;
+    }
+
+    // printf();
+    if (notation_is_piece_char(move_string[0])) {
+
+    }
+
+    return move;
+}
+
+
+MoveNotation notation_move_new(Piece piece, TileNotation origin, TileNotation target, int move_type);
+
+
+// Converts move notation to a move
+Move notation_to_move(MoveNotation notation) {
+    Move move = move_new(
+        notation_tile_to_position(notation.origin),
+        notation_tile_to_position(notation.target)
+    );
+
+    return move;
+}

src/algebraic_notation.h

@@ -0,0 +1,83 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#ifndef algebraic_notation_h
+#define algebraic_notation_h
+
+
+#include "position.h"
+#include "piece.h"
+#include "move.h"
+
+
+typedef struct TileNotation {
+    char file;
+    unsigned int rank;
+} TileNotation;
+
+
+// Converts a tile notation to a position on the board
+Position notation_tile_to_position(TileNotation notation);
+
+
+char* notation_tile_to_string(TileNotation tile);
+
+
+void notation_tile_to_string_cpy(TileNotation tile, char* dest);
+
+
+TileNotation notation_tile_from_string(const char* tile_string);
+
+
+TileNotation notation_tile_new(char file, unsigned int rank);
+
+
+// Converts
+TileNotation notation_tile_from_pos(Position pos);
+
+
+// Returns a piece character. Upper case for white, lower case for black
+char notation_piece_to_char(Piece piece);
+
+
+// Returns 1 if character is one of the piece characters, 0 otherwise
+int notation_is_piece_char(char character);
+
+
+typedef struct MoveNotation {
+    Piece piece;
+    TileNotation origin;
+    TileNotation target;
+    int move_type;
+} MoveNotation;
+
+
+char* notation_move_to_string(MoveNotation move);
+
+
+MoveNotation* notation_move_from_string(const char* move_string);
+
+
+MoveNotation notation_move_new(Piece piece, TileNotation origin, TileNotation target, int move_type);
+
+
+// Converts move notation to a move
+Move notation_to_move(MoveNotation notation);
+
+#endif

src/board.c

@@ -0,0 +1,584 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#include "board.h"
+#include "tile.h"
+#include "position.h"
+#include "util.h"
+#include "algebraic_notation.h"
+#include <stddef.h>
+#include <stdlib.h>
+
+
+
+// Returns a newly allocated chess board with pieces placed 
+Board* board_new_default() {
+    Board* board = NULL;
+
+    board = (Board*) malloc(sizeof(Board) * 1);
+    if (!board) {
+        return NULL;
+    }
+
+    board->rows = 8;
+    board->columns = 8;
+    board->tiles = (Tile*) malloc(sizeof(Tile) * (board->rows * board->columns));
+    if (!board->tiles) {
+        free(board);
+        return NULL;
+    }
+
+    // Initialize the board with empty tiles
+    for (int r = 0; r < board->rows; r++) {
+        for (int c = 0; c < board->columns; c++) {
+            board->tiles[r * board->columns + c] = tile_new_empty(position_new(r, c));
+        }
+    }
+
+    // Put pieces into their initial positions
+
+    // White
+    board_place_piece(board, position_new(0, 0), piece_new(WHITE, ROOK));
+    board_place_piece(board, position_new(0, 1), piece_new(WHITE, KNIGHT));
+    board_place_piece(board, position_new(0, 2), piece_new(WHITE, BISHOP));
+    board_place_piece(board, position_new(0, 3), piece_new(WHITE, KING));
+    board_place_piece(board, position_new(0, 4), piece_new(WHITE, QUEEN));
+    board_place_piece(board, position_new(0, 5), piece_new(WHITE, BISHOP));
+    board_place_piece(board, position_new(0, 6), piece_new(WHITE, KNIGHT));
+    board_place_piece(board, position_new(0, 7), piece_new(WHITE, ROOK));
+    board_place_piece(board, position_new(1, 0), piece_new(WHITE, PAWN));
+    board_place_piece(board, position_new(1, 1), piece_new(WHITE, PAWN));
+    board_place_piece(board, position_new(1, 2), piece_new(WHITE, PAWN));
+    board_place_piece(board, position_new(1, 3), piece_new(WHITE, PAWN));
+    board_place_piece(board, position_new(1, 4), piece_new(WHITE, PAWN));
+    board_place_piece(board, position_new(1, 5), piece_new(WHITE, PAWN));
+    board_place_piece(board, position_new(1, 6), piece_new(WHITE, PAWN));
+    board_place_piece(board, position_new(1, 7), piece_new(WHITE, PAWN));
+
+    // Black 
+    board_place_piece(board, position_new(7, 0), piece_new(BLACK, ROOK));
+    board_place_piece(board, position_new(7, 1), piece_new(BLACK, KNIGHT));
+    board_place_piece(board, position_new(7, 2), piece_new(BLACK, BISHOP));
+    board_place_piece(board, position_new(7, 3), piece_new(BLACK, KING));
+    board_place_piece(board, position_new(7, 4), piece_new(BLACK, QUEEN));
+    board_place_piece(board, position_new(7, 5), piece_new(BLACK, BISHOP));
+    board_place_piece(board, position_new(7, 6), piece_new(BLACK, KNIGHT));
+    board_place_piece(board, position_new(7, 7), piece_new(BLACK, ROOK));
+    board_place_piece(board, position_new(6, 0), piece_new(BLACK, PAWN));
+    board_place_piece(board, position_new(6, 1), piece_new(BLACK, PAWN));
+    board_place_piece(board, position_new(6, 2), piece_new(BLACK, PAWN));
+    board_place_piece(board, position_new(6, 3), piece_new(BLACK, PAWN));
+    board_place_piece(board, position_new(6, 4), piece_new(BLACK, PAWN));
+    board_place_piece(board, position_new(6, 5), piece_new(BLACK, PAWN));
+    board_place_piece(board, position_new(6, 6), piece_new(BLACK, PAWN));
+    board_place_piece(board, position_new(6, 7), piece_new(BLACK, PAWN));
+
+
+    return board;
+}
+
+
+/*
+Returns a newly allocated chess board with custom amount of 
+rows and columns, without pieces placed
+*/ 
+Board* board_new_empty_custom(unsigned int rows, unsigned int columns) {
+    Board* board = NULL;
+    return board;
+}
+
+
+// Frees up board and sets the pointer to it to NULL
+void board_delete(Board** board) {
+    if (board == NULL) {
+        return;
+    } else if (*board == NULL) {
+        return;
+    }
+
+    free((*board)->tiles);
+    free(*board);
+    *board = NULL;
+
+    return;
+}
+
+
+// Prints board to some FILE
+void board_print(const Board* board, FILE* out) {
+    if (!board || !out) {
+        return;
+    }
+
+    // Files
+    fputc(' ', out);
+    for (unsigned int i = 0; i < board->columns; i++) {
+        if (i > 0) {
+            fputc(' ', out);
+        }
+        fputc(0x61 + i, out);
+    }
+    fputc('\n', out);
+
+
+    // Upper border
+    fputc(' ', out);
+    for (unsigned int i = 0; i < board->columns; i++) {
+        if (i + 1 != board->columns) {
+            fputc('_', out);
+        }
+        fputc('_', out);
+    }
+    fputc('\n', out);
+
+
+    for (unsigned int r = 0; r < board->rows; r++) {
+        // Left border
+        fputc('|', out);
+
+        for (unsigned int c = 0; c < board->columns; c++) {
+            // Tile
+            char tile_character = '\0';
+
+            if ((r + c) % 2 == 0) {
+                // tile_character = '▓';
+                tile_character = '#';
+            } else {
+                // tile_character = '░';
+                tile_character = ' ';
+            }
+
+            Tile* tile = board_get_tile(board, position_new(r, c));
+            if (tile->piece.type != NONE) {
+                tile_character = notation_piece_to_char(tile->piece);
+            }
+
+            if (c > 0) {
+                fputc(' ', out);
+            }
+            fputc(tile_character, out);
+        }
+
+        // Right border
+        fputc('|', out);
+        
+
+        // Ranks
+        fprintf(out, " %d", board->rows - r);
+
+        fputc('\n', out);
+    }
+
+    // Lower border
+    fputc(' ', out);
+    for (unsigned int i = 0; i < board->columns; i++) {
+        if (i + 1 != board->columns) {
+            fputc('-', out);
+        }
+        fputc('-', out);
+    }
+    fputc('\n', out);
+    
+
+    return;
+}
+
+
+// Checks if given tile position is in bounds on this board. Returns 1 if it is, 0 - otherwise
+int board_is_tile_in_bounds(const Board* board, Position pos) {
+    if (pos.row >= board->rows || pos.column >= board->columns) {
+        return 0;
+    }
+
+    return 1;
+}
+
+
+
+// Retrieves a tile on provided position. If available - returns a pointer to it, if not - returns NULL
+Tile* board_get_tile_raw(const Board* board, Position pos) {
+    if (!board) {
+        return NULL;
+    }
+
+    if (!board_is_tile_in_bounds(board, pos)) {
+        return NULL;
+    }
+
+    return &board->tiles[(pos.row * board->columns) + pos.column];
+}
+
+
+/*
+Retrieves a tile on provided position as if (0, 0) is the bottom left tile. If available 
+- returns a pointer to it, if not - returns NULL.
+*/ 
+Tile* board_get_tile(const Board* board, Position pos) {
+    /*
+    Invert position so, for example (0, 0) would be the leftmost 
+    tile on the bottom (as it should be)
+    */
+    Position inverted_pos = position_new(
+        _sub_abs(pos.row + 1, board->rows), 
+        _sub_abs(pos.column + 1, board->columns)
+    );
+
+    return board_get_tile_raw(board, inverted_pos);
+}
+
+
+// Returns all tiles with pieces on them on the board
+Tile** board_get_occupied_tiles(const Board* board) {
+    if (!board) {
+        return NULL;
+    }
+
+    unsigned int i = 0;
+    Tile** occupied_tiles = (Tile**) malloc(sizeof(Tile) * board->rows * board->columns);
+    if (!occupied_tiles) {
+        return NULL;
+    }
+
+    // Loop through the whole board
+    Tile* tile = NULL;
+    for (unsigned int r = 0; r < board->rows; r++) {
+        for (unsigned int c = 0; c < board->columns; c++) {
+            // Always in bounds
+            if (board_is_tile_occupied(board, position_new(r, c))) {
+                // It is occupied!
+                occupied_tiles[i] = tile;
+                i++;
+            }
+        }
+    }
+
+    // Realloc
+    occupied_tiles = realloc(occupied_tiles, sizeof(Tile) * i);
+
+    return occupied_tiles;
+}
+
+
+// Places a piece on a tile with provided position. Returns 1 if the piece has been placed, 0 if position is out of bounds
+int board_place_piece(Board* board, Position pos, Piece piece) {
+    if (!board) {
+        return 0;
+    }
+
+    /*
+    Invert position so, for example (0, 0) would be the leftmost 
+    tile on the bottom (as it should be)
+    */
+    Position inverted_pos = position_new(
+        _sub_abs(pos.row + 1, board->rows), 
+        _sub_abs(pos.column + 1, board->columns)
+    );
+
+    Tile* tile = board_get_tile(board, inverted_pos);
+    if (!tile) {
+        return 0;
+    }
+
+    // Place the piece
+    tile->piece = piece;
+
+    return 1;
+}
+
+
+// Checks if a tile of given position is occupied or not. Returns 1 if it is occupied, 0 - otherwise
+int board_is_tile_occupied(const Board* board, Position pos) {
+    if (!board) {
+        return 0;
+    }
+
+    Tile* tile = board_get_tile(board, pos);
+    if (!tile) {
+        return 0;
+    }
+
+    if (tile->piece.type == NONE) {
+        return 0;
+    }
+
+    return 1;
+}
+
+
+/*
+Returns all possible legal positions either in diagonal or in straight lines
+
+If mode is 0 - returns positions in straight lines, 1 - in diagonals, 2 - in both 
+*/
+Position* board_get_moves(const Board* board, const Tile* piece_tile, int mode, unsigned int* pos_count) {
+    if (!board || !piece_tile || !pos_count) {
+        return NULL;
+    }
+
+    unsigned int i = 0;
+    Position* legal_moves = (Position*) malloc(sizeof(Position) * board->rows * board->columns);
+    if (!legal_moves) {
+        return NULL;
+    }
+
+    switch (mode) {
+        case 0: {
+            for (unsigned int j = 0; j < 4; j++) {
+                int vx = CARDINALS[j].x;
+                int vy = CARDINALS[j].y;
+
+                int xtmp = piece_tile->position.row + vx;
+                int ytmp = piece_tile->position.column + vy;
+                while (board_is_tile_in_bounds(board, position_new(xtmp, ytmp))) {
+                    Tile* tile = board_get_tile(board, position_new(xtmp, ytmp));
+                    if (tile->piece.type == NONE) {
+                        legal_moves[i] = tile->position;
+                        i++;
+                    } else if (tile->piece.color != piece_tile->piece.color) {
+                        legal_moves[i] = tile->position;
+                        i++;
+                        break; // Don't proceed
+                    } else {
+                        break;
+                    }
+
+                    xtmp = xtmp + vx;
+                    ytmp = ytmp + vy;
+                }
+            }
+            break;
+        }
+
+        case 1: {
+            for (unsigned int j = 0; j < 4; j++) {
+                int vx = DIAGONALS[j].x;
+                int vy = DIAGONALS[j].y;
+
+                int xtmp = piece_tile->position.row + vx;
+                int ytmp = piece_tile->position.column + vy;
+                while (board_is_tile_in_bounds(board, position_new(xtmp, ytmp))) {
+                    Tile* tile = board_get_tile(board, position_new(xtmp, ytmp));
+                    if (tile->piece.type == NONE) {
+                        legal_moves[i] = tile->position;
+                        i++;
+                    } else if (tile->piece.color != piece_tile->piece.color) {
+                        legal_moves[i] = tile->position;
+                        i++;
+                        break; // Don't proceed
+                    } else {
+                        break;
+                    }
+
+                    xtmp = xtmp + vx;
+                    ytmp = ytmp + vy;
+                }
+            }
+            break;
+        }
+
+        case 2: {
+            for (unsigned int j = 0; j < 4; j++) {
+                int vx = CARDINALS[j].x;
+                int vy = CARDINALS[j].y;
+
+                int xtmp = piece_tile->position.row + vx;
+                int ytmp = piece_tile->position.column + vy;
+                while (board_is_tile_in_bounds(board, position_new(xtmp, ytmp))) {
+                    Tile* tile = board_get_tile(board, position_new(xtmp, ytmp));
+                    if (tile->piece.type == NONE) {
+                        legal_moves[i] = tile->position;
+                        i++;
+                    } else if (tile->piece.color != piece_tile->piece.color) {
+                        legal_moves[i] = tile->position;
+                        i++;
+                        break; // Don't proceed
+                    } else {
+                        break;
+                    }
+
+                    xtmp = xtmp + vx;
+                    ytmp = ytmp + vy;
+                }
+            }
+
+            for (unsigned int j = 0; j < 4; j++) {
+                int vx = DIAGONALS[j].x;
+                int vy = DIAGONALS[j].y;
+
+                int xtmp = piece_tile->position.row + vx;
+                int ytmp = piece_tile->position.column + vy;
+                while (board_is_tile_in_bounds(board, position_new(xtmp, ytmp))) {
+                    Tile* tile = board_get_tile(board, position_new(xtmp, ytmp));
+                    if (tile->piece.type == NONE) {
+                        legal_moves[i] = tile->position;
+                        i++;
+                    } else if (tile->piece.color != piece_tile->piece.color) {
+                        legal_moves[i] = tile->position;
+                        i++;
+                        break; // Don't proceed
+                    } else {
+                        break;
+                    }
+
+                    xtmp = xtmp + vx;
+                    ytmp = ytmp + vy;
+                }
+            }
+            break;
+        }
+
+        default: {
+            return NULL;
+        }
+    }
+
+    legal_moves = realloc(legal_moves, sizeof(Position) * i);
+    *pos_count = i;
+
+    return legal_moves;
+}
+
+
+// Returns all possible legal rook moves. Returns NULL if given tile does not contain a rook piece 
+Position* board_get_rook_moves(const Board* board, const Tile* rook_tile, unsigned int* pos_count) {
+    if (!board || !rook_tile || !pos_count) {
+        return NULL;
+    }
+
+    if (rook_tile->piece.type != ROOK) {
+        return NULL;
+    }
+
+
+    return board_get_moves(board, rook_tile, 0, pos_count);
+}
+
+
+/*
+Checks if a move is legal on this board.
+
+Returns 1 - if the move is legal, 0 - otherwise
+*/
+int board_is_move_legal(const Board* board, Move move) {
+    // Check if the tiles are not out of bounds
+    if (!board_is_tile_in_bounds(board, move.origin) || 
+        !board_is_tile_in_bounds(board, move.target)
+    ) {
+        
+        return 0;
+    }
+
+    // Check if there is a piece at all
+    if (board_get_tile(board, move.origin)->piece.type == NONE) {
+        return 0;
+    }
+
+    Tile* origin_tile = board_get_tile(board, move.origin);
+    Tile* target_tile = board_get_tile(board, move.target);
+    
+    // Check based on the piece type
+    Piece origin_piece = origin_tile->piece;    
+    switch (origin_piece.type) {
+        case KING: {
+            if (position_distance(move.origin, move.target) > 1) {
+                // Too far away
+                return 0;
+            }
+
+            // See if the target tile is occupied or not
+            if (tile_is_occupied(*target_tile)) {
+                // The tile is occupied
+                if (target_tile->piece.color == origin_piece.color) {
+                    // The pieces are allied, can't go there
+                    return 0;
+                }
+            }
+
+            return 1;
+        }
+
+        case QUEEN: {
+            return 1;
+        }
+
+        case ROOK: {
+            unsigned int pos_count = 0;
+            Position* legal_positions = board_get_rook_moves(
+                board, 
+                board_get_tile(board, move.origin),
+                &pos_count
+            );
+            
+            for (unsigned int i = 0; i < pos_count; i++) {
+                if (legal_positions[i].row == move.target.row &&
+                    legal_positions[i].column == move.target.column
+                ) 
+                {
+                    // This position is allowed to be moved to
+                    free(legal_positions);
+                    return 1;
+                }
+            }
+
+            free(legal_positions);
+            return 0;
+        }
+
+        case KNIGHT: {
+            return 1;
+        }
+
+        case BISHOP: {
+            return 1;
+        }
+
+        case PAWN: {
+            return 1;
+        }
+
+        default: {
+            // Non reachable
+            return 0;
+        }
+    }
+}
+
+
+/*
+Moves piece from one place to other, 
+checking whether it is a legal move or not.
+
+Returns 1 if a move has been successfully done,
+0 - if it is an illegal move
+*/ 
+int board_process_move(Board* board, Move move) {
+    if (!board_is_move_legal(board, move)) {
+        return 0;
+    }
+
+    // The tiles are legal, no need to re-check
+    Tile* tile_origin = board_get_tile(board, move.origin);
+    Tile* tile_target = board_get_tile(board, move.target);
+
+    // Move the piece from one tile to another
+    tile_target->piece = tile_origin->piece;
+    tile_origin->piece.type = NONE;
+
+    return 1;
+}

src/board.h

@@ -0,0 +1,143 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#ifndef board_h
+#define board_h
+
+#include "tile.h"
+#include "move.h"
+#include "position.h"
+#include "piece.h"
+#include <stdio.h>
+
+
+typedef struct Vec2 {
+    int x;
+    int y;
+} Vec2;
+
+
+static const Vec2 CARDINALS[4] = {
+    {x: 1, y: 0}, {x: 0, y: 1},
+    {x: -1, y: 0}, {x: 0, y: -1}
+};
+
+
+static const Vec2 DIAGONALS[4] = {
+    {x: 1, y: 1}, {x: -1, y: 1},
+    {x: 1, y: -1}, {x: -1, y: -1}
+};
+
+
+static const Vec2 KNIGHTDELTAS[8] = {
+    {x: 1, y: 2}, {x: 2, y: 1},
+    {x: -1, y: 2}, {x: -2, y: 1},
+    {x: 1, y: -2}, {x: 2, y: -1},
+    {x: -1, y: -2}, {x: -2, y: -1}
+};
+
+
+typedef struct Board {
+    unsigned int rows;
+    unsigned int columns;
+    Tile* tiles;
+} Board;
+
+
+// Returns a newly allocated chess board with pieces placed 
+Board* board_new_default();
+
+
+/*
+Returns a newly allocated chess board with custom amount of 
+rows and columns, without pieces placed
+*/ 
+Board* board_new_empty_custom(unsigned int rows, unsigned int columns);
+
+
+// Frees up board and sets the pointer to it to NULL
+void board_delete(Board** board);
+
+
+// Checks if given tile position is in bounds on this board. Returns 1 if it is, 0 - otherwise
+int board_is_tile_in_bounds(const Board* board, Position pos);
+
+
+// Places a piece on a tile with provided position. Returns 1 if the piece has been placed, 0 if position is out of bounds
+int board_place_piece(Board* board, Position pos, Piece piece);
+
+
+// Retrieves a tile on provided position. If available - returns a pointer to it, if not - returns NULL
+Tile* board_get_tile_raw(const Board* board, Position pos);
+
+
+/*
+Retrieves a tile on provided position as if (0, 0) is the bottom left tile. If available 
+- returns a pointer to it, if not - returns NULL.
+*/ 
+Tile* board_get_tile(const Board* board, Position pos);
+
+
+// Returns all tiles with pieces on them on the board
+Tile** board_get_occupied_tiles(const Board* board);
+
+
+// Checks if a tile of given position is occupied or not. Returns 1 if it is occupied, 0 - otherwise
+int board_is_tile_occupied(const Board* board, Position pos);
+
+
+
+// Prints board to some FILE
+void board_print(const Board* board, FILE* out);
+
+
+/*
+Returns all possible legal positions either in diagonal or in straight lines
+
+If mode is 0 - returns positions in straight lines, 1 - in diagonals, 2 - in both 
+*/
+Position* board_get_moves(const Board* board, const Tile* piece_tile, int mode, unsigned int* pos_count);
+
+
+// Returns all possible legal king positions. Returns NULL if given tile does not contain a king piece 
+Position* board_get_king_moves(const Board* board, const Tile* king_tile, unsigned int* pos_count);
+
+
+// Returns all possible legal king positions. Returns NULL if given tile does not contain a rook piece 
+Position* board_get_rook_moves(const Board* board, const Tile* rook_tile, unsigned int* pos_count);
+
+
+/*
+Checks if a move is legal on this board.
+
+Returns 1 - if the move is legal, 0 - otherwise
+*/
+int board_is_move_legal(const Board* board, Move move);
+
+
+/*
+Moves piece from one place to other, 
+checking whether it is a legal move or not.
+
+Returns 1 if a move has been successfully done,
+0 - if it is an illegal move
+*/ 
+int board_process_move(Board* board, Move move);
+
+#endif

src/chess.c

@@ -0,0 +1,157 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#include "chess.h"
+#include "algebraic_notation.h"
+#include <stdlib.h>
+
+
+Chess* chess_new(Options options) {
+    if (!options.input || !options.output) {
+        return NULL;
+    }
+
+    Chess* game = (Chess*) malloc(sizeof(Chess) * 1);
+    if (!game) {
+        return NULL;
+    }
+
+    game->board = board_new_default();
+    game->moves_made = 0;
+    game->turn = WHITE;
+    game->state = READY;
+    game->options = options;
+
+    return game;
+}
+
+
+void chess_delete(Chess** chess) {
+    if (!chess) {
+        return;
+    }
+
+    if (!*chess) {
+        return;
+    }
+
+
+    board_delete(&(*chess)->board);
+    free(*chess);
+    *chess = NULL;
+
+    return;
+}
+
+
+void chess_display(const Chess* chess) {
+    char* color_string = color_to_string(chess->turn);
+    fprintf(
+        chess->options.output,
+        "[%s to move; %d moves made]\n\n",
+        color_string,
+        chess->moves_made    
+    );
+    free(color_string);
+
+    board_print(chess->board, chess->options.output);
+    fprintf(chess->options.output, "\n");
+    
+    return;
+}
+
+
+Move* chess_take_move_input(Chess* chess) {
+    if (!chess) {
+        return NULL;
+    }
+
+    // Ask for input
+    fprintf(chess->options.output, "Move: ");
+    char* input = (char*) malloc(sizeof(char) * 64);
+    input = fgets(input, 64, chess->options.input);
+
+    // Try to parse input
+    MoveNotation* move_notation = notation_move_from_string(input);
+    if (!move_notation) {
+        // Failed!
+        return NULL;
+    }
+
+    // Convert it to a useable move
+    Move* move = (Move*) malloc(sizeof(Move) * 1);
+    if (!move) {
+        free(move_notation);
+        return NULL;
+    }
+    *move = notation_to_move(*move_notation);
+    free(move_notation);
+
+    return move;
+}
+
+
+void chess_toggle_turn(Chess* chess) {
+    if (!chess) {
+        return;
+    }
+
+    if (chess->turn == WHITE) {
+        chess->turn = BLACK;
+    } else {
+        chess->turn = WHITE;
+    }
+
+    return;
+}
+
+
+void chess_next_turn(Chess* chess) {
+    if (!chess) {
+        return;
+    }
+
+    // Keep asking for a legitimate move
+    Move* move = NULL;
+    int result = 0;
+    while (1) {
+        // Get a move
+        move = chess_take_move_input(chess);
+        if (!move) {
+            printf("Invalid move input!\n");
+            continue;
+        }
+        
+        // Make a move
+        result = board_process_move(chess->board, *move);
+        if (!result) {
+            printf("Illegal move!\n");
+            free(move);
+            continue;
+        }
+
+        break;
+    }
+    free(move);
+
+    chess->moves_made++;
+    chess_toggle_turn(chess);
+
+    return;
+}

src/chess.h

@@ -0,0 +1,72 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#ifndef chess_h
+#define chess_h
+
+
+#include <stdio.h>
+#include "board.h"
+
+
+typedef enum GameState {
+    READY,
+    RUNNING,
+    WHITEWON,
+    BLACKWON
+} GameState;
+
+
+typedef struct Options {
+    FILE* input;
+    FILE* output;
+    int use_ansi;
+} Options;
+
+
+typedef struct Chess {
+    Board* board;
+    Color turn;
+    unsigned int moves_made;
+    unsigned int timer_white_ms;
+    unsigned int timer_black_ms;
+    GameState state;
+    Options options;
+} Chess;
+
+
+Chess* chess_new(Options options);
+
+
+void chess_display(const Chess* chess);
+
+
+Move* chess_take_move_input(Chess* chess);
+
+
+void chess_toggle_turn(Chess* chess);
+
+
+void chess_next_turn(Chess* chess);
+
+
+void chess_delete(Chess** chess);
+
+
+#endif

src/main.c

@@ -0,0 +1,82 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#include <stdio.h>
+#include <string.h>
+#include <stddef.h>
+#include "chess.h"
+
+
+const char* VERSION = "0.1.0";
+
+int main(int argc, const char** argv) {
+    int use_ansi = 0;
+
+    unsigned int i = 0;
+    while (i < (unsigned int) argc) {
+        if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0) {
+            printf(
+                "chess -[h|v|na]\n\n\
+-h --help -> prints this help message\n\
+-v --version -> prints version information\n\
+-a --ansi -> use ANSI escape codes to output colors\n\
+"
+            );
+            return 0;
+        }
+
+        if (strcmp(argv[i], "-v") == 0 || strcmp(argv[i], "--version") == 0) {
+            printf(
+                "c3hess v%s\n(C) 2023 Kasyanov Nikolay Alexeyevich (Unbewohnte)\n\n\
+This program is free software: you can redistribute it and/or modify\n\
+it under the terms of the GNU Affero General Public License as published by\n\
+the Free Software Foundation, either version 3 of the License, or\n\
+(at your option) any later version.\n\
+\n\
+This program is distributed in the hope that it will be useful,\n\
+but WITHOUT ANY WARRANTY; without even the implied warranty of\n\
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\n\
+GNU Affero General Public License for more details.\n\
+\n\
+You should have received a copy of the GNU Affero General Public License\n\
+along with this program.  If not, see <https://www.gnu.org/licenses/>.\n", VERSION);
+            return 0;
+        }
+
+        if (strcmp(argv[i], "-na") == 0 || strcmp(argv[i], "--no-ansi") == 0) {
+            use_ansi = 1;
+        }
+
+        i++;
+    } 
+
+    Chess* game = chess_new((Options) {
+        input: stdin,
+        output: stdout,
+        use_ansi: use_ansi
+    });
+    game->state = RUNNING;
+    while (game->state == RUNNING) {
+        chess_display(game);
+        chess_next_turn(game);
+    }
+    chess_delete(&game);
+
+    return 0;
+}

src/move.c

@@ -0,0 +1,29 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#include "move.h"
+
+
+Move move_new(Position origin, Position target) {
+    Move move;
+    move.origin = origin;
+    move.target = target;
+
+    return move;
+}

src/move.h

@@ -0,0 +1,46 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#ifndef move_h
+#define move_h
+
+#include "piece.h"
+#include "position.h"
+
+
+typedef enum MoveType {
+    MOVE        = 1 << 0,
+    LONGCASTLE  = 1 << 1,
+    SHORTCASTLE = 1 << 2,
+    CHECK       = 1 << 3,
+    CHECKMATE   = 1 << 4,
+    PROMOTION   = 1 << 5,
+    CAPTURE     = 1 << 6
+} MoveType;
+
+
+typedef struct Move {
+    Position origin;
+    Position target;
+} Move;
+
+
+Move move_new(Position origin, Position target);
+
+#endif

src/piece.c

@@ -0,0 +1,59 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#include "piece.h"
+#include <stdlib.h>
+#include <string.h>
+
+
+// Color to a string representation
+char* color_to_string(Color color) {
+    char* color_string = (char*) malloc(sizeof(char) * 6);
+    if (!color_string) {
+        return NULL;
+    }
+
+    switch (color) {
+        case WHITE: {
+            strcpy(color_string, "WHITE\0");
+            break;
+        }
+        case BLACK: {
+            strcpy(color_string, "BLACK\0");
+            break;
+        }
+
+        default: {
+            free(color_string);
+            return NULL;
+        }
+    }
+
+    return color_string;
+}
+
+
+// Creates a new piece
+Piece piece_new(Color color, PieceType type) {
+    Piece new_piece;
+    new_piece.color = color;
+    new_piece.type = type;
+    
+    return new_piece;
+}

src/piece.h

@@ -0,0 +1,57 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#ifndef piece_h
+#define piece_h
+
+
+// Color of a piece
+typedef enum Color {
+    WHITE,
+    BLACK
+} Color;
+
+
+// Color to a string representation
+char* color_to_string(Color color);
+
+
+// Piece type enumeration
+typedef enum PieceType {
+    NONE,
+    KING,
+    QUEEN,
+    ROOK,
+    BISHOP,
+    KNIGHT,
+    PAWN
+} PieceType;
+
+
+typedef struct Piece {
+    Color color;
+    PieceType type;
+} Piece;
+
+
+// Creates a new piece
+Piece piece_new(Color color, PieceType type);
+
+
+#endif

src/position.c

@@ -0,0 +1,138 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#include "position.h"
+#include "util.h"
+
+
+// Returns a copy of a new position
+Position position_new(unsigned int row, unsigned int column) {
+    Position new_pos;
+    new_pos.row = row;
+    new_pos.column = column;
+
+    return new_pos;
+}
+
+
+// Returns 1 if position (which) is diagonal to the other (to_which) position, 0 - otherwise
+int position_is_diagonal_to(Position which, Position to_which) {
+    if (_sub_abs(which.column, to_which.column) == _sub_abs(which.row, to_which.row)) {
+        return 1;
+    }
+
+    return 0;
+}
+
+
+// Returns 1 if position (which) is in a straight (not diagonal) line to the other one (to_which), returns 0 if not
+int position_is_straight_to(Position which, Position to_which) {
+    if (which.row == to_which.row || which.column == to_which.column) {
+        return 1;
+    }
+    
+    return 0;
+}
+
+
+// Returns a diagonal distance between two positions
+int position_diagonal_distance(Position which, Position to_which) {
+    return _sub_abs(which.column, to_which.column);
+}
+
+
+int _max(int x, int y) {
+    if (x > y) {
+        return x;
+    }
+
+    return y;
+}
+
+// Returns a distance between the two tile positions
+int position_distance(Position which, Position to_which) {
+    // 0 0 - 1 1 gives 1
+    // 0 0 - 2 0 gives 2
+    // 0 0 - 0 3 gives 3
+    return _max(_sub_abs(which.row, to_which.row), _sub_abs(which.column, to_which.column));
+}
+
+
+// Returns a position with the row incremented
+Position position_up(Position pos) {
+    return position_new(pos.row + 1, pos.column);
+}
+
+// Returns a position with the row decremented
+Position position_down(Position pos) {
+    if (pos.row == 0) {
+        return pos;
+    }
+
+    return position_new(pos.row - 1, pos.column);
+}
+
+// Returns a position with the column decremented
+Position position_left(Position pos) {
+    if (pos.column == 0) {
+        return pos;
+    }
+
+    return position_new(pos.row, pos.column - 1);
+}
+
+// Returns a position with the column incremented
+Position position_right(Position pos) {
+    return position_new(pos.row, pos.column + 1);
+}
+
+
+// Returns a position with the row incremented and column incremented
+Position position_up_right(Position pos) {
+    return position_new(pos.row + 1, pos.column + 1);
+}
+
+
+// Returns a position with the row incremented and column decremented
+Position position_up_left(Position pos) {
+    if (pos.column == 0) {
+        return pos;
+    }
+
+    return position_new(pos.row + 1, pos.column - 1);
+}
+
+// Returns a position with the row decremented and column incremented
+Position position_down_right(Position pos) {
+    if (pos.row == 0) {
+        return pos;
+    }
+
+    return position_new(pos.row - 1, pos.column + 1);
+}
+
+
+// Returns a position with the row decremented and column decremented
+Position position_down_left(Position pos) {
+    if (pos.row == 0 || pos.column == 0) {
+        return pos;
+    }
+
+    return position_new(pos.row - 1, pos.column - 1);
+}

src/position.h

@@ -0,0 +1,79 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#ifndef position_h
+#define position_h
+
+typedef struct Position {
+    unsigned int row;
+    unsigned int column;
+} Position;
+
+
+// Returns a copy of a new position
+Position position_new(unsigned int row, unsigned int column);
+
+
+// Returns 1 if position (which) is diagonal to the other (to_which) position, 0 - otherwise
+int position_is_diagonal_to(Position which, Position to_which);
+
+
+// Returns 1 if position (which) is in a straight (not diagonal) line to the other one (to_which), returns 0 if not
+int position_is_straight_to(Position which, Position to_which);
+
+
+// Returns a diagonal distance between two positions
+int position_diagonal_distance(Position which, Position to_which);
+
+
+// Returns a distance between the two tile positions
+int position_distance(Position which, Position to_which);
+
+
+// Returns a position with the row incremented
+Position position_up(Position pos);
+
+
+// Returns a position with the row decremented
+Position position_down(Position pos);
+
+
+// Returns a position with the column decremented
+Position position_left(Position pos);
+
+
+// Returns a position with the column incremented
+Position position_right(Position pos);
+
+
+// Returns a position with the row incremented and column incremented
+Position position_up_right(Position pos);
+
+
+// Returns a position with the row incremented and column decremented
+Position position_up_left(Position pos);
+
+// Returns a position with the row decremented and column incremented
+Position position_down_right(Position pos);
+
+
+// Returns a position with the row decremented and column decremented
+Position position_down_left(Position pos);
+
+#endif

src/tile.c

@@ -0,0 +1,50 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#include "tile.h"
+#include <stddef.h>
+
+// Creates a copy of a new tile
+Tile tile_new(Position position, Piece piece) {
+    Tile tile;
+    tile.position = position;
+    tile.piece = piece;
+
+    return tile;
+}
+
+
+// Creates a copy of an empty tile
+Tile tile_new_empty(Position position) {
+    Tile tile;
+    tile.position = position;
+    tile.piece.type = NONE;
+
+    return tile;
+}
+
+
+// Returns 1 if the tile is occupied and 0 if it is not 
+int tile_is_occupied(Tile tile) {
+    if (tile.piece.type == NONE) {
+        return 0;
+    }
+
+    return 1;
+}

src/tile.h

@@ -0,0 +1,46 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#ifndef tile_h
+#define tile_h
+
+#include "piece.h"
+#include "position.h"
+
+typedef struct Tile {
+    Position position;
+    Piece piece;
+} Tile;
+
+
+// Creates a copy of a new tile
+Tile tile_new(Position position, Piece piece);
+
+
+// Creates a copy of an empty tile
+Tile tile_new_empty(Position position);
+
+
+// Returns 1 if the tile is occupied and 0 if it is not 
+int tile_is_occupied(Tile tile);
+
+
+
+
+#endif

src/util.c

@@ -0,0 +1,30 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#include "util.h"
+
+
+// Subtracts smaller value from bigger value
+unsigned int _sub_abs(unsigned int x, unsigned int y) {
+    if (x > y) {
+        return x - y;
+    }
+
+    return y - x;
+}

src/util.h

@@ -0,0 +1,27 @@
+/*
+c3hess - Console Chess written in C
+Copyright (C) 2023 Kasyanov Nikolay Alexeyevich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+#ifndef util_h
+#define util_h
+
+// Subtracts smaller value from bigger value
+unsigned int _sub_abs(unsigned int x, unsigned int y);
+
+
+#endif