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board.c
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board.c
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/*
* Copyright 2014-2015 by Wade T. Cline (Frostsnow)
*
* "2048" is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* "2048" is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with "2048". If not, see <http://www.gnu.org/licenses/>.
*/
#include "board.h"
int board_done(struct board* board) {
int i;
int j;
int k;
// Check for winning number.
for (i = 0; i < BOARD_ROWS; i++) {
for (j = 0; j < BOARD_COLUMNS; j++) {
if (board->tiles[i][j] == 2048) {
return 1;
}
}
}
// Check for zeroes
for (i = 0; i < BOARD_ROWS; i++) {
for (j = 0; j < BOARD_COLUMNS; j++) {
if (!board->tiles[i][j]) {
return 0;
}
}
}
// Check for possible horizontal merge.
for (i = 0; i < BOARD_ROWS; i++) {
j = -1;
while ((k = ++j + 1) < BOARD_COLUMNS) {
if (board->tiles[i][j] == board->tiles[i][k]) {
return 0;
}
}
}
// Check for possible verical merge.
for (i = 0; i < BOARD_COLUMNS; i++) {
j = -1;
while ((k = ++j + 1) < BOARD_ROWS) {
if (board->tiles[j][i] == board->tiles[k][i]) {
return 0;
}
}
}
// No possible merges.
return -1;
}
void board_free(struct board* board) {
// Close the score file.
close(board->score_file);
}
unsigned board_get_tiles_empty(struct board* board) {
int i;
int j;
unsigned count;
// Calculate the number of empty tiles on the board.
count = 0;
for (i = 0; i < BOARD_ROWS; i++) {
for (j = 0; j < BOARD_COLUMNS; j++) {
count += (board->tiles[i][j] == 0);
}
}
// Return the calculated number.
return count;
}
void board_init(struct board* board) {
// Initialize the scores.
board->score_current = 0;
board_init_score(board);
// Initialize the tiles.
board_tiles_clear(board);
// Add two tiles to the board.
board_plop(board);
board_plop(board);
}
void board_init_score(struct board* board) {
char directory_path[128];
char file_path[128];
char* home;
// Get filepaths.
if (!(home = getenv("HOME"))) {
fprintf(stderr, "Unable to get home directory.");
goto out;
}
strncpy(directory_path, home, sizeof(directory_path));
if (strlen(directory_path) + strlen("/.2048") + 1 > 128) {
fprintf(stderr, "Directory path too long.");
goto out;
}
strncat(directory_path, "/.2048", strlen("/.2048"));
strncpy(file_path, home, sizeof(file_path));
if (strlen(file_path) + strlen("/.2048/score_top") + 1 > 128) {
fprintf(stderr, "File path too long.");
goto out;
}
strncat(file_path, "/.2048/score_top", sizeof("/.2048/score_top"));
// Open the top scores file.
if ((board->score_file = open(file_path, O_RDWR)) == -1) {
int directory;
// Create program directory.
if ((directory = open(directory_path, O_DIRECTORY | O_RDONLY))
== -1) {
if (mkdir(directory_path, 0755) == -1) {
perror("Unable to create save path.");
goto out;
}
} else {
close(directory);
}
// Create top scores file.
if ((board->score_file = open(file_path, O_CREAT | O_RDWR,
0644)) == -1) {
perror("Unable to create save file.");
goto out;
}
// Set initial score.
board->score_top = 0;
} else {
// Read in top score.
if (read(board->score_file, &board->score_top,
sizeof(board->score_top)) == -1 ) {
perror("Unable to read in top score.");
goto out;
}
}
// Return safely.
return;
out:
// Score file neither found nor loaded.
board->score_top = 0;
board->score_file = 0;
return;
}
int board_merge_down(struct board* board) {
int i;
int j;
int k;
int merge;
// Merge elements downwards.
merge = 0;
for (i = 0; i < BOARD_COLUMNS; i++) {
j = BOARD_ROWS - 1;
while (1) {
// Find two potential elements to merge.
while (j >= 0 && !board->tiles[j][i]) {
j--;
}
k = j - 1;
while (k >= 0 && !board->tiles[k][i]) {
k--;
}
if (k < 0) {
break;
}
// Try to merge the tiles.
if (board->tiles[j][i] == board->tiles[k][i]) {
board_tiles_merge(board,
&board->tiles[k][i],
&board->tiles[j][i]);
j = k - 1;
merge = 1;
} else {
j = k;
}
}
}
// Return whether an item was merged or not.
return merge;
}
int board_merge_left(struct board* board) {
int i;
int j;
int k;
int merge;
// Merge items leftwards.
merge = 0;
for (i = 0; i < BOARD_ROWS; i++) {
j = 0;
while (1) {
// Two two potential tiles to merge.
while (j < BOARD_COLUMNS && !board->tiles[i][j]) {
j++;
}
k = j + 1;
while (k < BOARD_COLUMNS && !board->tiles[i][k]) {
k++;
}
if (k >= BOARD_COLUMNS) {
break;
}
// Try to merge the tiles.
if (board->tiles[i][j] == board->tiles[i][k]) {
board_tiles_merge(board,
&board->tiles[i][j],
&board->tiles[i][k]);
j = k + 1;
merge = 1;
} else {
j = k;
}
}
}
// Return whether a tile was merged or not.
return merge;
}
int board_merge_right(struct board* board) {
int i;
int j;
int k;
int merge;
// Merge items rightward.
merge = 0;
for (i = 0; i < BOARD_ROWS; i++) {
j = BOARD_ROWS - 1;
while (1) {
// Find potential tiles to merge.
while (j >= 0 && !board->tiles[i][j]) {
j--;
}
k = j - 1;
while (k >= 0 && !board->tiles[i][k]) {
k--;
}
if (k < 0) {
break;
}
// Try to merge the tiles.
if (board->tiles[i][j] == board->tiles[i][k]) {
board_tiles_merge(board,
&board->tiles[i][k],
&board->tiles[i][j]);
j = k - 1;
merge = 1;
} else {
j = k;
}
}
}
// Return whether a tile was merged or not.
return merge;
}
int board_merge_up(struct board* board) {
int i;
int j;
int k;
int merge;
// Merge elements upwards.
merge = 0;
for (i = 0; i < BOARD_COLUMNS; i++) {
j = 0;
while (1) {
// Find two potential tiles to merge.
while (j < BOARD_ROWS && !board->tiles[j][i]) {
j++;
}
k = j + 1;
while (k < BOARD_ROWS && !board->tiles[k][i]) {
k++;
}
if (k >= BOARD_ROWS) {
break;
}
// Try to merge the tiles.
if (board->tiles[j][i] == board->tiles[k][i]) {
board_tiles_merge(board,
&board->tiles[j][i],
&board->tiles[k][i]);
j = k + 1;
merge = 1;
} else {
j = k;
}
}
}
// Return whether an item was merged or not.
return merge;
}
int board_move_down(struct board* board) {
char a = board_merge_down(board);
return a | board_shift_down(board);
}
int board_move_left(struct board* board) {
char a = board_merge_left(board);
return a | board_shift_left(board);
}
int board_move_right(struct board* board) {
char a = board_merge_right(board);
return a | board_shift_right(board);
}
int board_move_up(struct board* board) {
char a = board_merge_up(board);
return a | board_shift_up(board);
}
void board_plop(struct board* board) {
int i;
int j;
unsigned target;
unsigned tiles_empty;
// Count number of empty tiles.
tiles_empty = board_get_tiles_empty(board);
// Choose a random tile to palce the value into.
target = rand() % tiles_empty;
// Place the value into the tile. Implemented poorly.
tiles_empty = 0;
for (i = 0; i < BOARD_ROWS; i++) {
for (j = 0; j < BOARD_COLUMNS; j++) {
if (target == tiles_empty && board->tiles[i][j] == 0) {
board->tiles[i][j] = (rand() % 100 <=
BOARD_4SPAWN_CHANCE) ? 4 : 2;
tiles_empty++;
} else if (board->tiles[i][j] == 0) {
tiles_empty++;
}
}
}
}
void board_print(struct board* board) {
int i;
int j;
// Print the board's score.
printf(" Top: %5u\n Current: %5u\n\n", board->score_top,
board->score_current);
// Print the board's tiles.
for (i = 0; i < BOARD_ROWS; i++) {
printf(" ");
for (j = 0; j < BOARD_COLUMNS; j++) {
if (board->tiles[i][j]) {
printf("%4u ", board->tiles[i][j]);
} else {
printf(" . ");
}
}
printf("\n");
}
}
void board_reset(struct board* board) {
// Clear the current score.
board->score_current = 0;
// Clear the tiles.
board_tiles_clear(board);
// Place new starting tiles.
board_plop(board);
board_plop(board);
}
void board_score_updated(struct board* board) {
// Check for new top score.
if (board->score_current <= board->score_top) {
// Nothing to do.
return;
}
// Update in-game score.
board->score_top = board->score_current;
// Update score file.
if (!board->score_file) {
// Nothing to do.
return;
}
if (lseek(board->score_file, 0, SEEK_SET) == -1) {
fprintf(stderr, "Error updating score file: %i", errno);
return;
}
if (write(board->score_file, &board->score_top,
sizeof(board->score_top)) == -1) {
fprintf(stderr, "Error writing to score file: %i", errno);
return;
}
}
int board_shift_up(struct board* board) {
int i;
int j;
unsigned k;
int valid;
// Shift tiles up the columns.
valid = 0;
for (i = 0; i < BOARD_COLUMNS; i++) {
// Find first free tile in the column.
k = 0;
while (k < BOARD_ROWS && board->tiles[k][i]) {
k++;
}
// Shift tiles up the column.
for (j = k + 1; j < BOARD_ROWS; j++) {
if (board->tiles[j][i]) {
board->tiles[k++][i] = board->tiles[j][i];
board->tiles[j][i] = 0;
valid = 1;
}
}
}
// Return move status.
return valid;
}
int board_shift_down(struct board* board) {
int i;
int j;
int k;
int valid;
// Shift tiles down the columns.
valid = 0;
for (i = 0; i < BOARD_COLUMNS; i++) {
// Find the last free tile in the column.
k = BOARD_ROWS - 1;
while (k >= 0 && board->tiles[k][i]) {
k--;
}
// Shift tiles down the column.
for (j = k - 1; j >= 0; j--) {
if (board->tiles[j][i]) {
board->tiles[k--][i] = board->tiles[j][i];
board->tiles[j][i] = 0;
valid = 1;
}
}
}
// Return move status.
return valid;
}
int board_shift_left(struct board* board) {
int i;
int j;
unsigned k;
int valid;
// Shift tiles left across the rows.
valid = 0;
for (i = 0; i < BOARD_ROWS; i++) {
// Find the first free tile in the row.
k = 0;
while (k < BOARD_COLUMNS && board->tiles[i][k]) {
k++;
}
// Shift tiles left across the row.
for (j = k + 1; j < BOARD_COLUMNS; j++) {
if (board->tiles[i][j]) {
board->tiles[i][k++] = board->tiles[i][j];
board->tiles[i][j] = 0;
valid = 1;
}
}
}
// Return move status.
return valid;
}
int board_shift_right(struct board* board) {
int i;
int j;
int k;
int valid;
// Shift tiles right across the rows.
valid = 0;
for (i = 0; i < BOARD_ROWS; i++) {
// Find the last free tile in the row.
k = BOARD_COLUMNS - 1;
while (k >= 0 && board->tiles[i][k]) {
k--;
}
// Shift tiles right across the row.
for (j = k - 1; j >= 0; j--) {
if (board->tiles[i][j]) {
board->tiles[i][k--] = board->tiles[i][j];
board->tiles[i][j] = 0;
valid = 1;
}
}
}
// Return move status.
return valid;
}
void board_tiles_clear(struct board* board) {
int i;
int j;
// Clear the tiles.
for (i = 0; i < BOARD_ROWS; i++) {
for (j = 0; j < BOARD_COLUMNS; j++) {
board->tiles[i][j] = 0;
}
}
}
void board_tiles_merge(struct board* board, unsigned* a, unsigned* b) {
// Merge the two specified tiles.
board->score_current += (*a) += (*a);
(*b) = 0;
// Propogate updated score.
board_score_updated(board);
}