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sys_prog/assignment1-18/chessboard.c

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// vim: set ts=4 sw=4 et tw=80:
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#include <stdio.h>
#include "./chessboard.h"
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#include <string.h>
#include <stdbool.h>
#include <stdlib.h>
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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"
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" ┌───┬───┬───┬───┬───┬───┬───┬───┐\n");
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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"
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" a b c d e f g h\n");
}
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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) {
cb->position[to_row][to_col] = cb->position[from_row][from_col];
cb->position[from_row][from_col] = EMPTY;
}
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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;
}
inline enum player player(struct chessboard* cb, int row, int col) {
return cb->position[row][col] < 7 ? WHITE : BLACK;
}
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inline int sign(int n) {
return n == 0 ? 0 : (n > 0 ? 1 : -1);
}
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enum mstatus move_pawn(struct chessboard* cb, enum player p, int from_row,
int from_col, int to_row, int to_col) {
// 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 == 7 && to_row == 5 &&
is_empty(cb, 6, from_col))) &&
from_col == to_col &&
is_empty(cb, to_row, to_col)) {
cb_move(cb, from_row, from_col, to_row, to_col);
return VALID;
// one forward, no capture is valid
} 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)) {
cb_move(cb, from_row, from_col, to_row, to_col);
return VALID;
// 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) &&
player(cb, to_row, to_col) != p) {
cb_move(cb, from_row, from_col, to_row, to_col);
return VALID;
} else {
return INVALID;
}
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}
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enum mstatus 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;
for(; i != to_col || j != to_row; i += ii; j += jj) {
if (!is_empty(cb, i, j)) {
return INVALID;
}
}
cb_move(cb, from_row, from_col, to_row, to_col);
return VALID;
}
enum mstatus move_rook(struct chessboard* cb, enum player p, int from_row,
int from_col, int to_row, int to_col) {
if (to_row != from_row && to_col != from_col) {
return INVALID;
}
return check_empty_paths(cb, from_row, from_col, to_row, to_col);
}
enum mstatus move_bishop(struct chessboard* cb, enum player p, int from_row,
int from_col, int to_row, int to_col) {
if (from_row - to_row == from_col - to_col && from_row != to_row) {
return INVALID;
}
return check_empty_paths(cb, from_row, from_col, to_row, to_col);
}
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enum mstatus move(
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struct chessboard * cb, enum player p,
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
if (strlen(from) != 2 || strlen(to) != 2 || from[0] < 'a' || from[0] > 'h'
|| to[0] < 'a' || to[0] > 'h' || from[1] < '1' || from[1] > '8'
|| to[1] < '1' || to[1] > '8') {
return INVALID;
}
int from_row = from[0] - 'a', to_row = to[0] - 'a';
int from_col = from[1] - '1', to_col = to[0] - '1';
// 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;
}
// 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;
}
// 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) {
return INVALID;
}
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// if you try to move on the same spot, don't do it you buffoon
if (from_row == to_row && from_col == to_col) {
return INVALID;
}
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// try to understand which piece we are moving
switch (cb->position[from_row][from_col]) {
case WHITE_PAWN:
case BLACK_PAWN:
return move_pawn(cb, p, from_row, from_col, to_row, to_col);
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case WHITE_ROOK:
case BLACK_ROOK:
return move_rook(cb, p, from_row, from_col, to_row, to_col);
case WHITE_BISHOP:
case BLACK_BISHOP:
return move_bishop(cb, p, from_row, from_col, to_row, to_col);
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default:
return INVALID;
}
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}