testsAndMisc/C/lichess_random_engine/movegen.h

#ifndef MOVEGEN_H
#define MOVEGEN_H

#include <stdint.h>

// 0x88 board representation
#define BOARD_SIZE 128

typedef enum { WHITE = 0, BLACK = 1 } Color;

typedef enum {
    EMPTY = 0,
    WP = 1, WN, WB, WR, WQ, WK,
    BP = 7, BN, BB, BR, BQ, BK
} Piece;

typedef struct {
    // from and to squares in 0x88 (0..127), promotion piece in Piece enum or 0
    uint8_t from, to;
    uint8_t promo; // 0 if none
    uint8_t is_capture; // 1 if capture
    uint8_t is_enpassant; // 1 if en-passant capture
    uint8_t is_castle; // 1 if castle
} Move;

typedef struct {
    Piece board[BOARD_SIZE];
    Color side;
    // Castling rights: bit 0 white king-side, 1 white queen-side, 2 black king-side, 3 black queen-side
    uint8_t castle;
    int8_t ep_square; // -1 if none, else 0x88 square index
    int halfmove_clock;
    int fullmove_number;
} Position;

// Parsing and utilities
int parse_fen(Position *pos, const char *fen);
void set_startpos(Position *pos);
int square_from_algebraic(const char *uci4, int is_from);
int move_from_uci(const Position *pos, const char *uci, Move *out);
void make_move(Position *pos, const Move *m, Piece *captured_out);
void unmake_move(Position *pos, const Move *m, Piece captured);
int in_check(const Position *pos, Color side);

// Move generation
// Generates all pseudo-legal moves into moves[], returns count. If captures_only!=0, only captures (incl. ep) are generated
int gen_moves(const Position *pos, Move *moves, int max_moves, int captures_only);
int gen_moves_pseudo(const Position *pos, Move *moves, int max_moves, int captures_only);

#endif // MOVEGEN_H