This repository has been archived on 2021-10-31. You can view files and clone it, but cannot push or open issues or pull requests.
sys_prog/assignment1-18/chessboard.c

448 lines
15 KiB
C
Raw Normal View History

2019-08-04 15:27:01 +00:00
// vim: set ts=4 sw=4 et tw=80:
2019-08-04 13:56:15 +00:00
#include <stdio.h>
2019-08-04 15:27:01 +00:00
#include <string.h>
#include <stdbool.h>
#include <stdlib.h>
#include "./chessboard.h"
#define DEBUG_BUILD
#ifdef DEBUG_BUILD
#define DEBUG(...) fprintf(stderr, __VA_ARGS__);
#else
#define DEBUG(...) (void) 0;
#endif
static inline enum pieces cb_move(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col);
static inline void cb_move_restore(struct chessboard* cb, enum pieces piece,
int ex_from_row, int ex_from_col, int ex_to_row, int ex_to_col);
static inline int sign(int n);
static inline enum player player(struct chessboard* cb, int row, int col);
static inline bool is_empty(struct chessboard* cb, int row, int col);
static bool check_empty_paths(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col);
static bool can_move_pawn(struct chessboard* cb, enum player p,
int from_row, int from_col, int to_row, int to_col);
static bool can_move_rook(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col);
static bool can_move_knight(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col);
static bool can_move_bishop(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col);
static bool can_move_queen(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col);
static bool can_move_king(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col);
2019-08-04 13:56:15 +00:00
void init_chessboard(struct chessboard * cb) {
int i;
for (i = 0; i < 8; i++) {
cb->position[1][i] = WHITE_PAWN;
cb->position[6][i] = BLACK_PAWN;
}
cb->position[0][0] = WHITE_ROOK;
cb->position[0][1] = WHITE_KNIGHT;
cb->position[0][2] = WHITE_BISHOP;
cb->position[0][3] = WHITE_QUEEN;
cb->position[0][4] = WHITE_KING;
cb->position[0][5] = WHITE_BISHOP;
cb->position[0][6] = WHITE_KNIGHT;
cb->position[0][7] = WHITE_ROOK;
cb->position[7][0] = BLACK_ROOK;
cb->position[7][1] = BLACK_KNIGHT;
cb->position[7][2] = BLACK_BISHOP;
cb->position[7][3] = BLACK_QUEEN;
cb->position[7][4] = BLACK_KING;
cb->position[7][5] = BLACK_BISHOP;
cb->position[7][6] = BLACK_KNIGHT;
cb->position[7][7] = BLACK_ROOK;
int j;
for (i = 0; i < 8; i++) {
for (j = 2; j < 6; j++) {
cb->position[j][i] = EMPTY;
}
}
}
void print_chessboard(struct chessboard * cb) {
printf(" a b c d e f g h\n"
2019-08-04 15:27:01 +00:00
" ┌───┬───┬───┬───┬───┬───┬───┬───┐\n");
2019-08-04 13:56:15 +00:00
int i;
for (i = 7; i >= 0; i--) {
printf("%d │", i + 1);
int j;
for (j = 0; j < 8; j++) {
printf(" %s │", utf_8_pieces[cb->position[i][j]]);
}
putchar('\n');
if (i != 0) {
printf(" ├───┼───┼───┼───┼───┼───┼───┼───┤\n");
}
}
printf(" └───┴───┴───┴───┴───┴───┴───┴───┘\n"
2019-08-04 15:27:01 +00:00
" a b c d e f g h\n");
}
2019-08-04 13:56:15 +00:00
inline enum pieces cb_move(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col) {
enum pieces tmp = cb->position[to_row][to_col];
2019-08-04 15:27:01 +00:00
cb->position[to_row][to_col] = cb->position[from_row][from_col];
cb->position[from_row][from_col] = EMPTY;
return tmp;
}
inline void cb_move_restore(struct chessboard* cb, enum pieces piece,
int ex_from_row, int ex_from_col, int ex_to_row, int ex_to_col) {
cb->position[ex_from_row][ex_from_col] =
cb->position[ex_to_row][ex_to_col];
cb->position[ex_to_row][ex_to_col] = piece;
2019-08-04 15:27:01 +00:00
}
2019-08-04 16:41:55 +00:00
inline bool is_empty(struct chessboard* cb, int row, int col) {
2019-08-04 15:27:01 +00:00
return cb->position[row][col] == EMPTY;
}
inline enum player player(struct chessboard* cb, int row, int col) {
return cb->position[row][col] < 7 ? WHITE : BLACK;
2019-08-04 15:27:01 +00:00
}
2019-08-04 16:41:55 +00:00
inline int sign(int n) {
return n == 0 ? 0 : (n > 0 ? 1 : -1);
}
bool can_move_pawn(struct chessboard* cb, enum player p,
int from_row, int from_col, int to_row, int to_col) {
DEBUG("can_move_pawn: from: row %d col %d to: row %d col %d\n",
from_row, from_col, to_row, to_col);
2019-08-04 15:27:01 +00:00
// two forward if in the starting position, no capture is valid
if (((p == WHITE && from_row == 1 && to_row == 3 &&
is_empty(cb, 2, from_col)) ||
(p == BLACK && from_row == 6 && to_row == 4 &&
is_empty(cb, 5, from_col))) &&
from_col == to_col &&
is_empty(cb, to_row, to_col)) {
DEBUG("can_move_pawn: two forward, valid\n");
return true;
// one forward, no capture is valid
2019-08-04 15:27:01 +00:00
} else if (((p == WHITE && to_row - from_row == 1) ||
(p == BLACK && from_row - to_row == 1)) &&
from_col == to_col &&
is_empty(cb, to_row, to_col)) {
DEBUG("can_move_pawn: one forward no capture, valid\n");
return true;
// one forward, one left or right, with capture, is valid
} else if (to_row == from_row + (p == WHITE ? 1 : -1) &&
abs(from_col - to_col) == 1 &&
!is_empty(cb, to_row, to_col)) {
DEBUG("can_move_pawn: one forward diagonal capture, valid\n");
return true;
2019-08-04 15:27:01 +00:00
} else {
DEBUG("can_move_pawn: move pawn not valid\n");
return false;
2019-08-04 15:27:01 +00:00
}
2019-08-04 13:56:15 +00:00
}
bool check_empty_paths(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col) {
int ii = sign(to_row - from_row), jj = sign(to_col - from_col);
int i = from_row + ii, j = from_col + jj;
DEBUG("check_empty_paths: from: row %d col %d, to: row %d col %d, ii: %d,"
" jj: %d\n", from_row, from_col, to_row, to_col, ii, jj);
for (; !(i == to_row && j == to_col); i += ii, j += jj) {
if (!is_empty(cb, i, j)) {
DEBUG("check_empty_paths: position row %d col %d"
" is occupied\n", i, j);
return false;
}
}
2019-08-04 16:41:55 +00:00
return true;
2019-08-04 16:41:55 +00:00
}
bool can_move_rook(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col) {
if (to_row != from_row && to_col != from_col) {
return false;
2019-08-04 16:41:55 +00:00
}
return check_empty_paths(cb, from_row, from_col, to_row, to_col);
}
bool can_move_bishop(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col) {
if (abs(from_row - to_row) != abs(from_col - to_col)) {
return false;
2019-08-04 16:41:55 +00:00
}
return check_empty_paths(cb, from_row, from_col, to_row, to_col);
}
bool can_move_queen(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col) {
return can_move_bishop(cb, from_row, from_col, to_row, to_col) ||
can_move_rook(cb, from_row, from_col, to_row, to_col);
}
bool can_move_knight(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col) {
return (to_row == from_row + 2 && to_col == from_col + 1) ||
(to_row == from_row + 2 && to_col == from_col - 1) ||
(to_row == from_row - 2 && to_col == from_col + 1) ||
(to_row == from_row - 2 && to_col == from_col - 1) ||
(to_row == from_row + 1 && to_col == from_col + 2) ||
(to_row == from_row - 1 && to_col == from_col + 2) ||
(to_row == from_row + 1 && to_col == from_col - 2) ||
(to_row == from_row - 1 && to_col == from_col + 2);
}
bool can_move_king(struct chessboard* cb,
int from_row, int from_col, int to_row, int to_col) {
if (abs(to_row - from_row) > 1) {
DEBUG("can_move_king: row movement too big (from %d to %d)\n", from_row,
to_row);
return false;
}
if (abs(to_col - from_col) > 1) {
DEBUG("can_move_king: column movement too big (from %d to %d)\n",
from_col, to_col);
return false;
2019-08-11 11:23:29 +00:00
}
return true;
}
2019-08-11 11:23:29 +00:00
bool can_move(struct chessboard* cb, enum player p,
int from_row, int from_col, int to_row, int to_col) {
// try to understand which piece we are moving
switch (cb->position[from_row][from_col]) {
case WHITE_PAWN:
case BLACK_PAWN:
DEBUG("can_move: moving a pawn\n");
return can_move_pawn(cb, p, from_row, from_col, to_row, to_col);
case WHITE_ROOK:
case BLACK_ROOK:
DEBUG("can_move: moving a rook\n");
return can_move_rook(cb, from_row, from_col, to_row, to_col);
case WHITE_BISHOP:
case BLACK_BISHOP:
DEBUG("can_move: moving a bishop\n");
return can_move_bishop(cb, from_row, from_col, to_row, to_col);
case WHITE_QUEEN:
case BLACK_QUEEN:
DEBUG("can_move: moving a queen\n");
return can_move_queen(cb, from_row, from_col, to_row, to_col);
case WHITE_KNIGHT:
case BLACK_KNIGHT:
DEBUG("can_move: moving a knight\n");
return can_move_knight(cb, from_row, from_col, to_row, to_col);
case WHITE_KING:
case BLACK_KING:
DEBUG("can_move: moving a king\n");
return can_move_king(cb, from_row, from_col, to_row, to_col);
default:
DEBUG("can_move: piece not implemented\n");
return false;
}
2019-08-11 11:23:29 +00:00
}
2019-08-04 16:41:55 +00:00
void find_other_king(struct chessboard *cb, enum player p,
int* k_row, int* k_col) {
for (*k_row = 0; *k_row < 8; (*k_row)++) {
for (*k_col = 0; *k_col < 8; (*k_col)++) {
if ((p == BLACK && cb->position[*k_row][*k_col] == WHITE_KING) ||
(p == WHITE && cb->position[*k_row][*k_col] == BLACK_KING))
{
DEBUG("find_other_king: %s king in position row %d col %d\n",
p == WHITE ? "black" : "white", *k_row, *k_col);
return;
}
}
}
DEBUG("find_king: king not found");
}
2019-08-11 11:23:29 +00:00
bool player_checks(struct chessboard *cb, enum player p) {
int k_row, k_col;
find_other_king(cb, p, &k_row, &k_col);
int i, j;
for (i = 0; i < 8; i++) {
for (j = 0; j < 8; j++) {
if (!is_empty(cb, i, j) && player(cb, i, j) == p) {
DEBUG("player_checks: checking row %d col %d to attack king\n",
i, j);
if (can_move(cb, p, i, j, k_row, k_col)) {
DEBUG("player_checks: row %d col %d can attack %s king\n",
i, j, p == WHITE ? "black" : "white");
return true;
}
}
}
}
return false;
2019-08-11 11:23:29 +00:00
}
2019-08-04 16:41:55 +00:00
bool player_checkmates(struct chessboard *cb, enum player p) {
int i, j;
for (i = 0; i < 8; i++) {
for (j = 0; j < 8; j++) {
if (is_empty(cb, i, j) || player(cb, i, j) == p) {
continue;
}
int k, l;
for (k = 0; k < 8; k++) {
for (l = 0; l < 8; l++) {
if ((k == i && l == j) ||
is_empty(cb, k, l) ||
player(cb, k, l) != p) {
continue;
}
bool can = can_move(cb, p == BLACK ? WHITE : BLACK,
i, j, k, l);
if (!can) {
continue;
}
enum pieces tmp = cb_move(cb, i, j, k, l);
bool check = player_checks(cb, p);
cb_move_restore(cb, tmp, i, j, k, l);
if (!check) {
return false;
}
}
}
}
}
return true;
}
2019-08-04 13:56:15 +00:00
enum mstatus move(
2019-08-04 15:27:01 +00:00
struct chessboard * cb, enum player p,
const char * from, const char * to) {
2019-08-04 15:27:01 +00:00
// if you are giving us garbage, we behave like Rome's municipal services
if (strlen(from) != 2 || from[0] < 'a' || from[0] > 'h' || from[1] < '1'
|| from[1] > '8') {
DEBUG("move: 'from' input '%s' is invalid\n", from);
return INVALID;
}
if (to[0] < 'a' || to[0] > 'h' || to[1] < '1' || to[1] > '8'
|| strlen(to) != 2) {
DEBUG("move: 'to' input '%s' is invalid\n", to);
2019-08-04 15:27:01 +00:00
return INVALID;
}
int from_col = from[0] - 'a', to_col = to[0] - 'a';
int from_row = from[1] - '1', to_row = to[1] - '1';
2019-08-04 15:27:01 +00:00
// if you are moving thin air, EH VOLEVIH
2019-08-04 16:41:55 +00:00
if (is_empty(cb, from_row, from_col)) {
DEBUG("move: from is empty\n");
2019-08-04 15:27:01 +00:00
return INVALID;
}
// if you are moving someone else's pieces, "thou shall not steal"
2019-08-04 16:41:55 +00:00
if (player(cb, from_row, from_col) != p) {
DEBUG("move: moving piece of opponent\n");
2019-08-04 15:27:01 +00:00
return INVALID;
}
// if you are trying to suicide (capture your piecies), sorry but assisted
// suicide is not legal in italy
if (cb->position[to_row][to_col] != EMPTY &&
cb->position[from_row][from_col] / 7 ==
cb->position[to_row][to_col] / 7) {
DEBUG("move: capturing piece from moving player\n");
2019-08-04 15:27:01 +00:00
return INVALID;
}
2019-08-04 16:41:55 +00:00
// if you try to move on the same spot, don't do it you buffoon
if (from_row == to_row && from_col == to_col) {
DEBUG("move: moving to same position\n");
2019-08-04 16:41:55 +00:00
return INVALID;
}
bool check_before = player_checks(cb, p == WHITE ? BLACK : WHITE);
bool can = can_move(cb, p, from_row, from_col, to_row, to_col);
if (!can) {
2019-08-04 15:27:01 +00:00
return INVALID;
} else {
2019-08-20 11:09:37 +00:00
// FIXME: check if move is allowed in check state
enum pieces tmp = cb_move(cb, from_row, from_col, to_row, to_col);
if (player_checks(cb, p == WHITE ? BLACK : WHITE) && check_before) {
DEBUG("move: move does not end check state, invalid");
cb_move_restore(cb, tmp, from_row, from_col, to_row, to_col);
return INVALID;
} else if (player_checks(cb, p)) {
if (player_checkmates(cb, p)) {
return CHECK_MATE;
} else {
return CHECK;
2019-08-20 11:09:37 +00:00
}
} else {
return VALID;
}
}
}
int main() {
struct chessboard cb;
init_chessboard(&cb);
enum player p = WHITE;
char from[5], to[5];
while (true) {
print_chessboard(&cb);
printf("%s moves.\n", p == WHITE ? "White" : "Black");
printf("From: ");
fgets(from, 5, stdin);
// remove trailing \n: https://stackoverflow.com/q/2693776
strtok(from, "\n");
if (strcmp(from, "exit") == 0) {
printf("Exiting...\n");
return 0;
}
printf("To: ");
fgets(to, 5, stdin);
strtok(to, "\n");
enum mstatus s = move(&cb, p, from, to);
switch (s) {
case INVALID:
printf("Invalid move.\n");
break;
case VALID:
printf("No check/checkmate.\n");
break;
case CHECK:
printf("Check.\n");
break;
case CHECK_MATE:
printf("Checkmate, %s wins.\n", p == WHITE ? "white" : "black");
}
if (s != INVALID) {
p = !p; // switch player: this works since WHITE = 0 and BLACK = 1
}
2019-08-04 15:27:01 +00:00
}
2019-08-04 13:56:15 +00:00
}