gitea push

src/chess.c

@@ -1,195 +1,219 @@
-#include <stdio.h>
 #include "chess.h"
-#include "util.h"
 
-void init_board(board_t *board) {
-    for (int i = 0; i < BOARD_VERTICAL; i++) {
-        for (int j = 0; j < BOARD_HORIZONTAL; j++) {
-            *board[i][j] = BOARD_DEFAULT_CONFIG[i][j];
-        }
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+int **create_board(int rows, int cols) {
+  int **board = (int **)malloc(sizeof(int*) * rows);
+  if (!board) return NULL;
+  for (int i = 0; i < cols; i++) {
+    board[i] = (int *)malloc(sizeof(int));
+    if (!board[i]) return NULL; // should probably free all the previously allocated ones as well as the ** pointer
   }
+  return board;
 }
 
-void select_player(player_e *player, unsigned int round_count) {
-    if (round_count == 1) {
-        *player = WHITE;
-        return;
+move_t get_move(state_t state) {
+  move_t move;
+  int row_from, row_to;
+  char col_from, col_to;
+  printf("move (e.g. b1 a3) > ");
+  scanf("%c%d %c%d", &col_from, &row_from, &col_to, &row_to);
+
+  move.from = (v2_t){
+    .x = 97-col_from,
+    .y = state.board_rows-row_from};
+  move.to = (v2_t){
+    .x = 97-col_to,
+    .y = state.board_rows-row_to};
+
+  return move;
 }
 
-    if (*player == WHITE) {
-        *player = BLACK;
-        return;
+int board_get(state_t state, v2_t pos) {
+  return state.board[pos.y][pos.x];
 }
 
-    if (*player == BLACK) {
-        *player = WHITE;
-        return;
-    }
+void board_set(state_t *state, v2_t pos, int piece) {
+  state->board[pos.y][pos.x] = piece;
 }
 
-void show_help() {
-    puts(
-        "movement help:\n\
-        there is a prompt asking for where to move a piece every turn\n\
-        format: e.g. you want to move a knight from b1 to a3:\n\
-        you'd type -> b1 a3 <- (without the arrows)\n"
-    );
+bool is_move_dest_in_bounds(state_t state, move_t move) {
+  return
+    0 <= move.to.x && move.to.x < state.board_cols &&
+    0 <= move.to.y && move.to.y < state.board_rows;
 }
 
-// returns false if the numbers of letters are out of bounds
-bool is_move_in_bounds(move_t move) {
-    if (
-        is_int_in_range(move.from.x, 0, 7) &&
-        is_int_in_range(move.from.y, 0, 7) &&
-        is_int_in_range(move.to.x, 0, 7) &&
-        is_int_in_range(move.to.y, 0, 7)
-    ) {
-        return true;
-    } else {
-        return false;
-    }
+bool is_dest_empty(state_t state, move_t move) {
+  return board_get(state, move.to) == 0;
 }
 
-bool get_move(move_t *move) {
-    clear_stdin();
-
-    char _x_from, _x_to;
-    int _y_from, _y_to;
-    scanf("%c%d %c%d", 
-        &_x_from,
-        &_y_from,
-        &_x_to,
-        &_y_to
-    );
-
-    move->from.x = _x_from-96-1; // char to int conversion
-    move->from.y = _y_from-1;
-
-    move->to.x = _x_to-96-1;
-    move->to.y = _y_to-1;
-
-    return is_move_in_bounds(*move);
+bool is_dest_opposite_color(state_t state, move_t move) {
+  return (board_get(state, move.from) * board_get(state, move.to) < 0); // < 0 means different colors
 }
 
-bool compare_pos(pos_t a, pos_t b) {
-    return a.x == b.x && a.y == b.y;
+// white pieces are positive ints and black are negative
+bool is_dest_empty_or_opposite_color(state_t state, move_t move) {
+  return
+    is_dest_empty(state, move) ||
+    is_dest_opposite_color(state, move);
 }
 
-pos_t pos_multiply_scalar(pos_t a, int b) {
-    return (pos_t){a.x*b, a.y*b};
+v2_t v2(int x, int y) {
+  return (v2_t){x, y};
 }
 
 /**
- * check the wanted pos_t against all valid move options
- * of the current piece
+ *  0 -> a == b
+ * -1 -> a < b
+ *  1 -> a > b
  */
-bool is_move_legal(move_t move) {
-    valid_move_t valid_moves[PIECE_COUNT] = DEFAULT_VALID_MOVES;
-    switch (move.piece) {
-        case NONE:
-        case PAWN:
-        case KNIGHT:
-        case KING:
-            for (int i = 0; i < PIECE_COUNT; i++) {
-                for (int j = 0; 
-                    j < valid_moves[i].piece_move_count && 
-                    move.piece == valid_moves[i].piece; 
-                    j++
-                ) {
-                    pos_t new_pos = {move.from.x+move.to.x, move.from.y+move.to.y};
-                    if (compare_pos(new_pos, valid_moves[i].options[j]) == true) {
-                        return true;
-                    }
-                }
-            }
-            break;
-        case ROOK:
-        case BISHOP:
-        case QUEEN:
-            for (int i = 0; i < PIECE_COUNT; i++) {
-                for (int j = 0; 
-                    j < valid_moves[i].piece_move_count && 
-                    move.piece == valid_moves[i].piece; 
-                    j++
-                ) {
-                    /** NOTE: BOARD_HORIZONTAL assuming HORIZONTAL & VERTICAL are the same */
-                    for (int k = 0; k < BOARD_HORIZONTAL; k++) {
-                        pos_t new_pos = {
-                            move.from.x+move.to.x, 
-                            move.from.y+move.to.y
-                        };
-                        if (compare_pos(
-                            new_pos, 
-                            pos_multiply_scalar(valid_moves[i].options[j], k)
-                        ) == true) {
-                            return true;
-                        }
-                    }
-                }
-            }
-            break;            
-    }
-
-    return false;
-}
-
-bool is_none(board_t board, pos_t pos) {
-    return board[pos.y][pos.x] == NONE;
-}
-
-// the move can be:
-// 1.  legal x illegal
-// 2.  the 'to' pos could be occupied x non-occupied
-// 2a. it could be capturable x non-capturable
-bool validate_move(board_t board, move_t move) {
-    bool none = is_none(board, move.to);
-    bool move_legal = is_move_legal(move);
-    if (none == true && move_legal == true) {         
-        // free ability to move
-        return true;
-    } else if (none == false && move_legal == true) {
-        // capturing
-        return true;
+int v2_cmp(v2_t a, v2_t b) {
+  if (a.x == b.x && a.y == b.y) {
+    return 0;
+  } else if (a.x < b.x && a.y < b.y) {
+    return -1;
+  } else if (a.x > b.x && a.y > b.y) {
+    return 1;
   } else {
-        // otherwise, invalid move
+    return 99; // error code
+  }
+}
+
+bool is_piece_at_origin_able_to_make_move(state_t state, move_t move) {
+  // need to check all legal moves for the piece at move.from
+
+  unsigned int idx = abs(board_get(state, move.from));
+  for (int i = 0; i < state.valid_moves.piece_numbers[idx]; i++) {
+    if (v2_cmp(move.to, state,valid_moves.table[idx][i]) == 0) {
+      return true;
+    }
+  }
   return false;
 }
+
+bool is_move_valid(state_t state, move_t move) {
+  return is_move_dest_in_bounds(state, move) &&
+    is_dest_empty_or_opposite_color(state, move) &&
+    is_piece_at_origin_able_to_make_move(state, move);
 }
 
-/** TODO: capturing and promotions */
-bool perform_move(board_t *board, player_e player, move_t move) {
-    if (validate_move(*board, move) == true) {
-        *board[move.to.y][move.to.x] = move.piece; // move piece to wanted place
-        *board[move.from.y][move.from.x] = NONE; // erase the remnants
+// this only ever must get called AFTER made sure it is legal
+// with is_move_legal()
+void perform_move(state_t *state, move_t move) {
+  board_set(state, move.to, board_get(*state, move.from));
+  board_set(state, move.from, 0);
+}
+
+player_e get_dest_color(state_t state, move_t move) {
+  if (board_get(state, move.to) < 0) {
+    return BLACK;
+  } else if (board_get(state, move.to) > 0) {
+    return WHITE;
+  } else {
+    return EMPTY;
   }
 }
 
-end_condition_e check_edge_cases(board_t board) {
-
-}
-
-void announce_results(end_condition_e end_condition, player_e player) {
-    printf("The game has ended because of a ");
-
-    switch (end_condition) {
-        case CHECKMATE:
-            printf("CHECKMATE");
-            break;
-        case STALEMATE:
-            printf("STALEMATE");
-            break;
-    }
-
-    printf("\nand the player who has won is");
-
-    switch (player) {
+void check_captures(state_t *state, move_t move) {
+  // king cannot be captured
+  if (is_dest_opposite_color(*state, move) && abs(board_get(*state, move.to)) != 6) {
+    switch (get_dest_color(*state, move)) {
       case WHITE:
-            printf(" WHITE");
+        state->captured_by_black[state->by_black_capture_num++] =
+          board_get(*state, move.to);
         break;
       case BLACK:
-            printf(" BLACK");
+        state->captured_by_white[state->by_white_capture_num++] =
+          board_get(*state, move.to);
+        break;
+      case EMPTY:
+        break;
+    }
+  }
+}
+
+// if a pawn has reached the opposite side, change it into a queen
+// TODO: let the player choose the next piece
+void check_promotions(state_t *state, move_t move) {
+  if (board_get(*state, move.to) == 1 && move.to.y == 0) {
+    // 1, y = 0 => white pawn has reached the end
+    board_set(state, move.to, 5); // 5 -> Wqueen
+  } else if (board_get(*state, move.to) == -1 && move.to.y == state->board_cols-1) {
+    // -1, y = board_cols-1 => black pawn has reached the end
+    board_set(state, move.to, -5); // -5 -> Bqueen
+  }
+}
+
+// go through all the valid moves for all the pieces
+// of the opposite player and see if 'pos' is in there
+bool is_position_endangered(state_t state, v2_t pos) {
+  /**
+    * for every valid move of KING:
+    *   for every OPPOSITE COLOR PIECE:
+    *     check if the valid moves contain the KING's pos
+    * ->
+    *   1. iterate through the board
+    *   2. if found opposite color piece
+    *   3. -> for every valid move of this piece, check if it matches any of the kings positions
+    */
+  for (int col = 0; col < state.board_cols; col++) {
+    for (int row = 0; row < state.board_rows; row++) {
+      v2_t pos = (v2_t){row, col};
+      int piece = board_get(state, pos);
+      switch (state.active_player) {
+        case WHITE:
+          if (piece < 0) {
+            for (int i = 0; i < state.valid_moves.piece_numbers[piece]; i++) {
+              for (int j = 0; j < state.valid_moves.piece_numbers[6]; j++) {
+                if (v2_cmp(
+                  state.valid_moves.table[piece][i],
+                  state.valid_moves.table[6][j]) == 0
+                ) {
+                  return true;
+                }
+              }
+            }
+          }
+          break;
+        case BLACK:
+          if (piece > 0) {
+            for (int i = 0; i < state.valid_moves.piece_numbers[piece]; i++) {
+              for (int j = 0; j < state.valid_moves.piece_numbers[6]; j++) {
+                if (v2_cmp(
+                  state.valid_moves.table[piece][i],
+                  state.valid_moves.table[6][j]) == 0
+                ) {
+                  return true;
+                }
+              }
+            }
+          }
+          break;
+        case EMPTY:
+          break;
+      }
+    }
+  }
+
+  return false;
+}
+
+/** TODO: unimplemented */
+bool check_end_conditions(state_t state, move_t move) {
+  return false;
+}
+
+void switch_active_player(state_t *state) {
+  switch (state->active_player) {
+    case WHITE:
+      state->active_player = BLACK;
+      break;
+    case BLACK:
+      state->active_player = WHITE;
+      break;
+    case EMPTY:
       break;
   }
-
-    printf("! Congratulations.\n");
 }

src/chess.h

@@ -1,140 +1,66 @@
-#ifndef CHESS_H
-#define CHESS_H
-
-/* the "board" is the playable area on which
- * pieces move. pieces are represented by numbers:
- * 0 - no piece
- * 1 - pawn
- * 2 - rook
- * 3 - knight
- * 4 - bishop
- * 5 - queen
- * 6 - king
-*/
+#pragma once
 
 #include <stdbool.h>
 
-// board size constraints
-#define BOARD_HORIZONTAL 8
-#define BOARD_VERTICAL 8
+#define repeat(var, n) for (int var = 0; var < n; var++)
 
-// type abstractions
-typedef int board_t[BOARD_HORIZONTAL][BOARD_VERTICAL];
-
-#define PIECE_COUNT 7 // how many unique pieces are there
-#define MAX_PIECE_MOVE_COUNT 27 // the max possible num of options where to move in one moment
+// types of players
 typedef enum {
-    NONE,
-    PAWN,
-    ROOK,
-    KNIGHT,
-    BISHOP,
-    QUEEN,
-    KING
-} piece_e;
+  EMPTY,
+  WHITE,
+  BLACK
+} player_e;
 
+// 2d vector struct (used e.g. for directions or coords)
 typedef struct {
   int x;
   int y;
-} pos_t;
-
-typedef enum { WHITE, BLACK } player_e;
+} v2_t;
 
+// everything we need to identify and perform a move
 typedef struct {
-    // what
-    // where from
-    // where to
-    piece_e piece;
-    pos_t from;
-    pos_t to;
+  v2_t from;
+  v2_t to;
 } move_t;
 
-// the default arrangment of pieces on the board
-#define BOARD_DEFAULT_CONFIG \
-(board_t){\
-    {2,3,4,5,6,4,3,2},\
-    {1,1,1,1,1,1,1,1},\
-    {0,0,0,0,0,0,0,0},\
-    {0,0,0,0,0,0,0,0},\
-    {0,0,0,0,0,0,0,0},\
-    {1,1,1,1,1,1,1,1},\
-    {2,3,4,5,6,4,3,2}\
-}
-
 typedef struct {
-    piece_e piece;
-    pos_t options[MAX_PIECE_MOVE_COUNT];
-    unsigned int piece_move_count;
-} valid_move_t;
+  v2_t table[7][8];
+  int piece_numbers[7];
+} valid_moves_t;
 
-/** FIXED: ALSO DEPENDS ON THE STATE OF THE GAME - 
- *  e.g. a pawn cannot move two places in the middle 
- *  of the game but can in the first round 
- *  => ASSUME NO OTHER PIECES - then ALWAYS CHECK 
- *  FOR PIECE COLLISIONS and FOR ROUND COUNT 
- *  (pawn 1 || 2 move)
- */
+// appstate struct
+#define CAPTURABLE 16
+typedef struct {
+  unsigned int board_cols;
+  unsigned int board_rows;
+  int captured_by_white[CAPTURABLE];
+  unsigned int by_white_capture_num;
+  int captured_by_black[CAPTURABLE];
+  unsigned int by_black_capture_num;
+  player_e active_player;
+  valid_moves_t valid_moves;
+  int **board;
+} state_t;
 
- /** MAYBE: consider the POV from both sides???!!! */
 /**
-  * the NONE, PAWN, KNIGHT and KING pieces' relative_moves are
-  * treated like specific coordinates relative to their
-  * position, 
-  * whereas the BISHOP, ROOK and QUEEN pieces' 'moves'
-  * are treated as *directions* in which they can move rather than
-  * absolute x,y values -> e.g. the rook can move 
-  * up, down, left, right * n -> and then bounds & edge cases are checked
+ * pieces:
+ * 0   = empty
+ * +-1 = pawn
+ * +-2 = rook
+ * +-3 = knight
+ * +-4 = bishop
+ * +-5 = queen
+ * +-6 = king
  */
-#define DEFAULT_VALID_MOVES (valid_move_t[PIECE_COUNT]){\
-    {NONE, {}, 0},\
-    {PAWN, {\
-        { 0, -1}, {-1, -1}, {+1, -1}, { 0, -2}\
-    }, 4},\
-    {ROOK, {\
-        { 0, -1}, { 0, +1}, {-1,  0}, {+1,  0}\
-    }, 4},\
-    {KNIGHT, {\
-        {-1, -2}, {+1, -2}, {-2, -1}, {-2, +1},\
-        {+2, -1}, {+2, +1}, {-1, -2}, {-1, +2}\
-    }, 8},\
-    {BISHOP, {\
-        {-1, -1}, {-1, +1}, {+1, -1}, {+1, +1}\
-    }, 4},\
-    {QUEEN, {\
-        {0,  -1}, {0,  +1}, {-1,  0}, {+1,  0},\
-        {-1, -1}, {-1, +1}, {+1, -1}, {+1, +1}\
-    }, 8},\
-    {KING, {\
-        { 0, -1}, { 0, +1}, {-1,  0}, {+1,  0},\
-        {-1, -1}, {-1, +1}, {+1, -1}, {+1, +1}\
-    }, 8}\
-}
 
-typedef enum {
-    CHECKMATE,
-    STALEMATE
-} end_condition_e;
+int **create_board(int rows, int cols);
+move_t get_move(state_t state);
+bool is_move_valid(state_t state, move_t move);
+void perform_move(state_t *state, move_t move);
+void check_captures(state_t *state, move_t move);
+void check_promotions(state_t *state, move_t move);
+bool check_end_conditions(state_t state, move_t move);
+void switch_active_player(state_t *state);
 
-// initializes the board with the default configuration of pieces
-void init_board(board_t *board);
-
-// selects the player to currently play
-// if it is the first round, it selects white
-void select_player(player_e *player, unsigned int round_count);
-        
-// listens for a command to make a move by the currently playing player
-bool get_move(move_t *move);
-
-// performs the move if is it possible
-bool perform_move(board_t *board, player_e player, move_t move);
-
-// checks for captures, prommotions and mates
-end_condition_e check_edge_cases(board_t board);
-
-// if there is one of the mates, end the game and show who has won
-void announce_results(end_condition_e end_condition, player_e player);
-
-// shows a guide to help players understand the move prompt system
-void show_help();
-
-#endif // CHESS_H
+v2_t v2(int x, int y);
+int v2_cmp(v2_t a, v2_t b);

src/main.c

@@ -1,51 +1,67 @@
-// a chess implementation in pure C :)
-
-#include "util.h"
-#include "chess.h"
-
 /**
- * steps to victory:
- * 1. init the board with the default config
- * 2. game loop
- *  2a. select the current player (if first round - white starts)
- *  2b. wait for the movement of the current player
- *  2c. once a move is registered, perform it IF POSSIBLE
- *  2d. check for captures and/or promotions and/or mates (check, stale...)
- *  2e. if there is an end condition that is met, end the game; announce
- *      the results
+ * algo:
+ * 1. create a chess board
+ * 2. loop
+ * 2a. select the player to play
+ * 2b. they try to make a move
+ * 2c. the move gets validated
+ * 2d. if it can be made and it is legal, go ahead
+ * 2e. check for captures and promotions
+ * 2f. after each move, check for a stalemate or a checkmate condition => if there is -> end of the game
+ * 2g. if there is no end condition => it's the other player's turn
  */
 
+#include "chess.h"
+#include <string.h>
+
 int main() {
-    // variable defs
-    board_t board;
-    move_t move;
-    player_e player;
-    unsigned int round_count = 0;
-    end_condition_e end_condition;
-    bool running = true;
+  state_t state;
+  state.valid_moves = (valid_moves_t){
+    .table = {
+      {}, // 0
 
-    // algo begin
+      {v2( 0,-1), v2( 0,-2), v2(-1,-1), v2( 1,-1),
+       v2( 0, 1), v2( 0, 2), v2(-1, 1), v2( 1, 1)}, // 1
 
-    init_board(&board);
+      {v2( 0,-1), v2( 0, 1), v2(-1, 0), v2( 1, 0)}, // ...
 
-    show_help();
+      {v2(-1,-2), v2(-1, 2), v2(-2,-1), v2(-2, 1),
+       v2( 1,-2), v2( 1, 2), v2( 2,-1), v2( 2, 1)},
 
-    while (running) {
-        round_count++;
+      {v2(-1,-1), v2(-1, 1), v2( 1,-1), v2( 1, 1)},
 
-        select_player(&player, round_count);
+      {v2(-1,-1), v2(-1, 1), v2( 1,-1), v2( 1, 1),
+       v2( 0,-1), v2( 0, 1), v2(-1, 0), v2( 1, 0)},
 
-        get_move(&move);
+      {v2(-1,-1), v2(-1, 1), v2( 1,-1), v2( 1, 1),
+       v2( 0,-1), v2( 0, 1), v2(-1, 0), v2( 1, 0)}
+    },
+    .piece_numbers = {0, 8, 4, 8, 4, 8, 8}
+  };
+  memset(state.captured_by_white, 0, CAPTURABLE);
+  memset(state.captured_by_black, 0, CAPTURABLE);
+  state.by_white_capture_num = 0;
+  state.by_black_capture_num = 0;
+  state.board_rows = 8;
+  state.board_cols = 8;
+  state.board = create_board(state.board_rows, state.board_cols); // creates a constant struct => no need to check for memory issues
 
-        perform_move(&board, player, move);
+  state.active_player = WHITE;
 
-        end_condition = check_edge_cases(board);
-        if (end_condition == CHECKMATE || end_condition == STALEMATE) {
-            running = false;
-        }
+  while (true) {
+    move_t move = get_move(state);
+
+    if (is_move_valid(state, move)) {
+      check_captures(&state, move);   // checks for captures and modifies the state to keep track of the captures pieces
+
+      check_promotions(&state, move); // same thing as above but for promotions: pawn -> queen when at the end of the board, etc.
+
+      if (check_end_conditions(state, move)) break; // returns false if the game is supposed to end and true if it is supposed tu continue
+      perform_move(&state, move);
     }
 
-    announce_results(end_condition, player);
+    switch_active_player(&state);
+  }
 
-    return EXIT_SUCCESS;
+  return 0;
 }

src/util.c

@@ -1,14 +0,0 @@
-#include "util.h"
-#include <stdio.h>
-
-void clear_stdin() {
-    while (getchar() != '\n');
-}
-
-bool is_int_in_range(int x, int start, int end) {
-    if (start <= x && x <= end) {
-        return true;
-    } else {
-        return false;
-    }
-}

src/util.h

@@ -1,17 +0,0 @@
-#ifndef UTIL_H
-#define UTIL_H
-
-#include <stdbool.h>
-
-// misc. defines and methods
-
-#define EXIT_SUCCESS 0
-#define EXIT_FAILURE 1
-
-// for input handling consistency
-void clear_stdin();
-
-// self-explanatory
-bool is_int_in_range(int x, int start, int end);
-
-#endif // UTIL_H