203 lines
6.3 KiB
C
203 lines
6.3 KiB
C
// vim: set ts=4 sw=4 et tw=80:
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#include <stdio.h>
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#include "./chessboard.h"
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#include <string.h>
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#include <stdbool.h>
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#include <stdlib.h>
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void init_chessboard(struct chessboard * cb) {
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int i;
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for (i = 0; i < 8; i++) {
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cb->position[1][i] = WHITE_PAWN;
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cb->position[6][i] = BLACK_PAWN;
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}
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cb->position[0][0] = WHITE_ROOK;
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cb->position[0][1] = WHITE_KNIGHT;
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cb->position[0][2] = WHITE_BISHOP;
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cb->position[0][3] = WHITE_QUEEN;
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cb->position[0][4] = WHITE_KING;
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cb->position[0][5] = WHITE_BISHOP;
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cb->position[0][6] = WHITE_KNIGHT;
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cb->position[0][7] = WHITE_ROOK;
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cb->position[7][0] = BLACK_ROOK;
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cb->position[7][1] = BLACK_KNIGHT;
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cb->position[7][2] = BLACK_BISHOP;
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cb->position[7][3] = BLACK_QUEEN;
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cb->position[7][4] = BLACK_KING;
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cb->position[7][5] = BLACK_BISHOP;
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cb->position[7][6] = BLACK_KNIGHT;
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cb->position[7][7] = BLACK_ROOK;
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int j;
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for (i = 0; i < 8; i++) {
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for (j = 2; j < 6; j++) {
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cb->position[j][i] = EMPTY;
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}
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}
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}
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void print_chessboard(struct chessboard * cb) {
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printf(" a b c d e f g h\n"
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" ┌───┬───┬───┬───┬───┬───┬───┬───┐\n");
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int i;
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for (i = 7; i >= 0; i--) {
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printf("%d │", i + 1);
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int j;
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for (j = 0; j < 8; j++) {
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printf(" %s │", utf_8_pieces[cb->position[i][j]]);
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}
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putchar('\n');
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if (i != 0) {
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printf(" ├───┼───┼───┼───┼───┼───┼───┼───┤\n");
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}
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}
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printf(" └───┴───┴───┴───┴───┴───┴───┴───┘\n"
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" a b c d e f g h\n");
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}
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inline void cb_move(struct chessboard* cb, int from_row, int from_col, int to_row,
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int to_col) {
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cb->position[to_row][to_col] = cb->position[from_row][from_col];
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cb->position[from_row][from_col] = EMPTY;
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}
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inline bool is_empty(struct chessboard* cb, int row, int col) {
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return cb->position[row][col] == EMPTY;
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}
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inline enum player player(struct chessboard* cb, int row, int col) {
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return cb->position[row][col] < 7 ? WHITE : BLACK;
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}
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inline int sign(int n) {
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return n == 0 ? 0 : (n > 0 ? 1 : -1);
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}
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enum mstatus move_pawn(struct chessboard* cb, enum player p, int from_row,
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int from_col, int to_row, int to_col) {
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// two forward if in the starting position, no capture is valid
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if (((p == WHITE && from_row == 1 && to_row == 3 &&
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is_empty(cb, 2, from_col)) ||
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(p == BLACK && from_row == 7 && to_row == 5 &&
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is_empty(cb, 6, from_col))) &&
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from_col == to_col &&
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is_empty(cb, to_row, to_col)) {
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cb_move(cb, from_row, from_col, to_row, to_col);
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return VALID;
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// one forward, no capture is valid
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} else if (((p == WHITE && to_row - from_row == 1) ||
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(p == BLACK && from_row - to_row == 1)) &&
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from_col == to_col &&
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is_empty(cb, to_row, to_col)) {
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cb_move(cb, from_row, from_col, to_row, to_col);
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return VALID;
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// one forward, one left or right, with capture, is valid
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} else if (to_row = from_row + (p == WHITE ? 1 : -1) &&
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abs(from_col - to_col) == 1 &&
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!is_empty(cb, to_row, to_col) &&
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player(cb, to_row, to_col) != p) {
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cb_move(cb, from_row, from_col, to_row, to_col);
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return VALID;
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} else {
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return INVALID;
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}
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}
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enum mstatus check_empty_paths(struct chessboard* cb, int from_row,
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int from_col, int to_row, int to_col) {
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int ii = sign(to_row - from_row), jj = sign(to_col - from_col);
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int i = from_row + ii, j = from_col + jj;
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for(; i != to_col || j != to_row; i += ii; j += jj) {
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if (!is_empty(cb, i, j)) {
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return INVALID;
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}
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}
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cb_move(cb, from_row, from_col, to_row, to_col);
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return VALID;
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}
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enum mstatus move_rook(struct chessboard* cb, enum player p, int from_row,
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int from_col, int to_row, int to_col) {
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if (to_row != from_row && to_col != from_col) {
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return INVALID;
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}
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return check_empty_paths(cb, from_row, from_col, to_row, to_col);
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}
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enum mstatus move_bishop(struct chessboard* cb, enum player p, int from_row,
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int from_col, int to_row, int to_col) {
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if (from_row - to_row == from_col - to_col && from_row != to_row) {
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return INVALID;
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}
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return check_empty_paths(cb, from_row, from_col, to_row, to_col);
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}
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enum mstatus move(
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struct chessboard * cb, enum player p,
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const char * from, const char * to)
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{
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// if you are giving us garbage, we behave like Rome's municipal services
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if (strlen(from) != 2 || strlen(to) != 2 || from[0] < 'a' || from[0] > 'h'
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|| to[0] < 'a' || to[0] > 'h' || from[1] < '1' || from[1] > '8'
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|| to[1] < '1' || to[1] > '8') {
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return INVALID;
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}
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int from_row = from[0] - 'a', to_row = to[0] - 'a';
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int from_col = from[1] - '1', to_col = to[0] - '1';
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// if you are moving thin air, EH VOLEVIH
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if (is_empty(cb, from_row, from_col)) {
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return INVALID;
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}
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// if you are moving someone else's pieces, "thou shall not steal"
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if (player(cb, from_row, from_col) != p) {
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return INVALID;
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}
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// if you are trying to suicide (capture your piecies), sorry but assisted
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// suicide is not legal in italy
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if (cb->position[to_row][to_col] != EMPTY &&
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cb->position[from_row][from_col] / 7 ==
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cb->position[to_row][to_col] / 7) {
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return INVALID;
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}
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// if you try to move on the same spot, don't do it you buffoon
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if (from_row == to_row && from_col == to_col) {
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return INVALID;
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}
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// try to understand which piece we are moving
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switch (cb->position[from_row][from_col]) {
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case WHITE_PAWN:
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case BLACK_PAWN:
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return move_pawn(cb, p, from_row, from_col, to_row, to_col);
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case WHITE_ROOK:
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case BLACK_ROOK:
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return move_rook(cb, p, from_row, from_col, to_row, to_col);
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case WHITE_BISHOP:
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case BLACK_BISHOP:
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return move_bishop(cb, p, from_row, from_col, to_row, to_col);
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default:
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return INVALID;
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}
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}
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