--- a/src/chess/rules.h Thu Jul 30 18:34:15 2026 +0200
+++ b/src/chess/rules.h Thu Jul 30 19:17:38 2026 +0200
@@ -43,7 +43,11 @@
#define PIECE_PINNED 5
#define KING_IN_CHECK 6
#define KING_MOVES_INTO_CHECK 7
-#define RULES_VIOLATED 10
+#define MISSING_CHECK 8
+#define MISSING_CHECKMATE 9
+#define INVALID_CHECK 10
+#define INVALID_CHECKMATE 11
+#define RULES_VIOLATED 32
#define ENPASSANT_THREAT 0x40u
@@ -83,7 +87,7 @@
struct movetimeval {
uint64_t tv_sec;
- int32_t tv_usec; // important that this is signed b/c potential carry
+ int32_t tv_usec; /* important that this is signed b/c potential carry */
};
typedef struct {
@@ -92,9 +96,11 @@
Row fromrow;
File tofile;
Row torow;
- uint8_t promotion;
- uint8_t check;
+ Piece promotion;
+ uint8_t check; /* must always be set if checkmate is set */
+ uint8_t checkmate;
uint8_t capture;
+ uint8_t padding[7]; /* necessary for stable ABI across networks */
struct movetimeval timestamp;
struct movetimeval movetime;
char string[8];
@@ -189,7 +195,13 @@
}
static inline bool is_game_running(const GameState *gamestate) {
- return !(gamestate->checkmate || gamestate->wresign || gamestate->bresign || gamestate->threefold || gamestate->stalemate || gamestate->remis || gamestate->review);
+ return !(gamestate->checkmate || gamestate->wresign || gamestate->bresign
+ || gamestate->threefold || gamestate->stalemate || gamestate->remis
+ || gamestate->review);
+}
+
+static inline bool is_check_position(const GameState *gamestate) {
+ return gamestate->moves[gamestate->movecount - 1].check;
}
/**
@@ -242,7 +254,7 @@
* @param gamestate the current game state
* @return the color of the player who is next to move
*/
-Color current_color(GameState *gamestate);
+Color current_color(const GameState *gamestate);
/**
* Returns the piece at the specified position.
@@ -276,7 +288,29 @@
}
/**
- * Checks, if a specified field is covered by a piece of a certain color.
+ * Determines a list of possible moves to the specified field.
+ *
+ * The out-parameters may both be NULL, but if any of them is set, the other
+ * must be set, too.
+ *
+ * @param gamestate the current game state
+ * @param row row of the field to check
+ * @param file file of the field to check
+ * @param color the color of the piece that should move to the field
+ * @param moves the array where to store the moves
+ * (must be large enough, 16 is always enough)
+ * @param movecount a pointer where the number of moves is stored
+ * @return true, if any piece of the specified color can move to the specified
+ * field
+ */
+bool get_candidates(const GameState *gamestate, Row row, File file,
+ Color color, Move* moves, size_t* movecount);
+
+/**
+ * Checks, if a specified field is threatened by a piece of a certain color.
+ *
+ * A field is threatened, if there is a piece of the specified color that could
+ * capture an opponent piece on this field, regardless of being pinned.
*
* The out-parameters may both be NULL, but if any of them is set, the other
* must be set, too.
@@ -285,17 +319,17 @@
* @param row row of the field to check
* @param file file of the field to check
* @param color the color of the piece that should threaten the field
- * @param threats the array where to store the threats (should be able to hold
- * the rare maximum of 16 elements)
+ * @param threats the array where to store the threats
+ * (must be large enough, 16 is always enough)
* @param threatcount a pointer where the count of threats is stored
* @return true, if any piece of the specified color threatens the specified
- * field (i.e. could capture an opponent piece)
+ * field
*/
-bool get_threats(GameState *gamestate, Row row, File file,
+bool get_threats(const GameState *gamestate, Row row, File file,
Color color, Move* threats, size_t* threatcount);
/**
- * Checks, if a specified field is covered by a piece of a certain color AND
+ * Checks, if a specified field is threatened by a piece of a certain color AND
* if this piece is not pinned and therefore able to perform the move.
*
* The out-parameters may both be NULL, but if any of them is set, the other
@@ -305,17 +339,20 @@
* @param row row of the field to check
* @param file file of the field to check
* @param color the color of the piece that should threaten the field
- * @param threats the array where to store the threats (should be able to hold
- * the rare maximum of 16 elements)
+ * @param threats the array where to store the threats
+ * (must be large enough, 16 is always enough)
* @param threatcount a pointer where the count of threats is stored
* @return true, if any piece of the specified color threatens the specified
- * field (i.e. could capture an opponent piece)
+ * field and is not pinned
*/
-bool get_real_threats(GameState *gamestate, Row row, File file,
+bool get_real_threats(const GameState *gamestate, Row row, File file,
Color color, Move* threats, size_t* threatcount);
/**
- * Checks, if a specified field is covered by a piece of a certain color.
+ * Checks, if a specified field is threatened by a piece of a certain color.
+ *
+ * A field is threatened, if there is a piece of the specified color that could
+ * capture an opponent piece on this field, regardless of being pinned.
*
* @param gamestate the current game state
* @param row row of the field to check
@@ -330,7 +367,7 @@
/**
* Checks, if a specified field is attacked by a piece of a certain color.
*
- * I.e. the field is covered by a piece AND this piece is not pinned and
+ * I.e. the field is threatened by a piece AND this piece is not pinned and
* therefore able to perform the move.
*
* @param gamestate the current game state
@@ -346,8 +383,8 @@
/**
* Checks, if a specified field is protected by a piece of a certain color.
*
- * I.e. the field is covered by a piece that is NOT the king AND this piece is
- * not pinned and therefore able to perform the move.
+ * This is the same as is_attacked(), but only considers pieces that are not
+ * the king.
*
* @param gamestate the current game state
* @param row row of the field to check
@@ -356,7 +393,7 @@
* @return true, if any piece (excluding the king) of the specified color
* threatens the specified field and could capture an opponent piece
*/
-bool is_protected(GameState *gamestate, Row row, File file, Color color);
+bool is_protected(const GameState *gamestate, Row row, File file, Color color);
/**
* Checks, if the specified move cannot be performed, because the piece is
@@ -372,25 +409,51 @@
* @return true, if the move cannot be performed because the king would be in
* check after the move
*/
-bool is_pinned(GameState *gamestate, Move *move);
+bool is_pinned(const GameState *gamestate, const Move *move);
/**
* Evaluates a move syntactically and stores the move data in the specified
* object.
*
* When short algebraic notation is used, the source position is determined by
- * the evaluating the allowed moves according to the current game state.
+ * evaluating the allowed moves according to the current game state.
+ *
+ * This function expects correct notation of check and checkmate indicators.
+ * For a more lazy evaluation, use eval_move_lazy().
*
* For a purely syntactic check, regardless of whether a piece exists that is
* allowed to move that way, use check_move().
*
* @param gamestate the current game state
* @param mstr the input string to parse
+ * @param color the color of the player to evaluate the move for
* @param move a pointer to object where the move data shall be stored
- * @param color the color of the player to evaluate the move for
* @return status code (see macros in this file for the list of codes)
*/
-int eval_move(GameState *gamestate, const char *mstr, Move *move, Color color);
+int eval_move(const GameState *gamestate,
+ const char *mstr, Color color, Move *move);
+
+/**
+ * Evaluates a move syntactically and stores the move data in the specified
+ * object.
+ *
+ * When short algebraic notation is used, the source position is determined by
+ * evaluating the allowed moves according to the current game state.
+ *
+ * This function automatically corrects missing or incorrect check/checkmate
+ * indicators. Use eval_move() if you want to keep the original notation.
+ *
+ * For a purely syntactic check, regardless of whether a piece exists that is
+ * allowed to move that way, use check_move().
+ *
+ * @param gamestate the current game state
+ * @param mstr the input string to parse
+ * @param color the color of the player to evaluate the move for
+ * @param move a pointer to object where the move data shall be stored
+ * @return status code (see macros in this file for the list of codes)
+ */
+int eval_move_lazy(const GameState *gamestate,
+ const char *mstr, Color color, Move *move);
/**
* Syntactically checks a move without verifying that a piece exists that is
@@ -408,7 +471,7 @@
* @param move the move to validate
* @return status code (see macros in this file for the list of codes)
*/
-int validate_move(GameState *gamestate, Move *move);
+int validate_move(const GameState *gamestate, const Move *move);
/**
* Applies a move and deletes captured pieces.
@@ -427,7 +490,7 @@
* @param move_number the half-move that would now be played
* @param replay the struct to populate with the state at the specified move
*/
-void gamestate_at_move(GameState *gamestate,
+void gamestate_at_move(const GameState *gamestate,
unsigned move_number, GameState *replay);
/**
@@ -439,7 +502,7 @@
* @return the remaining time - if time control is disabled, this function
* always returns zero
*/
-uint16_t remaining_movetime2(GameState *gamestate, unsigned move_number);
+uint16_t remaining_movetime2(const GameState *gamestate, unsigned move_number);
/**
* Returns the remaining time on the clock for the specified player.
@@ -449,7 +512,7 @@
* @return the remaining time - if time control is disabled, this function
* always returns zero
*/
-uint16_t remaining_movetime(GameState *gamestate, Color color);
+uint16_t remaining_movetime(const GameState *gamestate, Color color);
/**
* Converts clock time to string.
@@ -472,7 +535,7 @@
* @param gamestate the current game state
* @return true if the game is in a threefold repetition position
*/
-bool check_threefold_repetition(GameState *gamestate);
+bool check_threefold_repetition(const GameState *gamestate);
#endif /* RULES_H */
