mirror of
https://codeberg.org/hkzlab/TK2048.git
synced 2025-12-25 21:32:16 +11:00
115 lines
3 KiB
C
115 lines
3 KiB
C
#include "game_logic.h"
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#include "utility.h"
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#include <string.h>
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static uint8_t game_grid_alpha[GRID_SIDE * GRID_SIDE];
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static uint8_t game_grid_beta[GRID_SIDE * GRID_SIDE];
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static uint8_t *front_grid = game_grid_alpha;
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static uint8_t *back_grid = game_grid_beta;
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void swap_grids(void);
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void swap_grids(void) {
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uint8_t *temp = front_grid;
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front_grid = back_grid;
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back_grid = temp;
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}
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uint8_t *get_front_grid(void) {
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return front_grid;
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}
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uint8_t add_random_tile(void) {
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uint16_t rand = lfsr_update();
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uint8_t tile_val = (rand & 0x000F) > 0x0D ? 2 : 1; // 90% chance of a tile of type 1 (a "2"), 10% of a type 2 (a "4")
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uint8_t rand_offset = rand >> 8;
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uint8_t tile_placed = 0;
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for (int8_t offset = 0; offset < GRID_SIDE * GRID_SIDE; offset++) {
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if (!front_grid[(offset + rand_offset)%(GRID_SIDE * GRID_SIDE)]) {
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front_grid[(offset + rand_offset)%(GRID_SIDE * GRID_SIDE)] = tile_val;
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tile_placed = 1;
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break;
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}
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}
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return tile_placed; // Return 0 if we were not able to place the tile
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}
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uint8_t *step_game(step_direction dir) {
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uint8_t start_offset;
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int8_t column_step;
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int8_t row_step;
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/*
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* UP: scans TOP to BOTTOM, RIGHT to LEFT
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* DOWN: scans BOTTOM to TOP, RIGHT to LEFT
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* LEFT: scans LEFT to RIGHT, TOP to BOTTOM
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* RIGHT: scans RIGHT to LEFT, TOP to BOTTOM
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*/
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switch(dir) {
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case UP:
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start_offset = GRID_SIDE - 1;
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column_step = GRID_SIDE;
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row_step = -1;
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break;
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case DOWN:
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start_offset = (GRID_SIDE * GRID_SIDE) - 1;
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column_step = -GRID_SIDE;
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row_step = -1;
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break;
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case LEFT:
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start_offset = 0;
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column_step = 1;
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row_step = GRID_SIDE;
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break;
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break;
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case RIGHT:
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start_offset = GRID_SIDE - 1;
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column_step = -1;
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row_step = GRID_SIDE;
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break;
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};
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// Clear the back grid
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memset(back_grid, 0, GRID_SIDE * GRID_SIDE);
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for (uint8_t row = 0; row < GRID_SIDE; row++) {
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for(uint8_t col = 0; col < GRID_SIDE; col++) {
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uint8_t current_offset = start_offset + (col * column_step) + (row * row_step);
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uint8_t sub_col;
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// Search for the first non-zero value in the front grid and copy it in the current place of the back grid (zeroing it in the front)
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for(sub_col = col; sub_col < GRID_SIDE; sub_col++) {
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uint8_t sub_col_offset = start_offset + (sub_col * column_step) + (row * row_step);
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if(front_grid[sub_col_offset]) {
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back_grid[current_offset] = front_grid[sub_col_offset];
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front_grid[sub_col_offset] = 0;
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break;
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}
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}
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// The value is still 0, we found nothing. On to the next row!
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if (!back_grid[current_offset]) break;
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// Now search if there is an identical value following this one, so we can merge them
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for(; sub_col < GRID_SIDE; sub_col++) {
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uint8_t sub_col_offset = start_offset + (sub_col * column_step) + (row * row_step);
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if(front_grid[sub_col_offset] == back_grid[current_offset]) {
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back_grid[current_offset]++; // Merge them (by increasing the value of the current square and removing the merged one)
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front_grid[sub_col_offset] = 0;
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break;
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}
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}
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}
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}
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swap_grids();
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return front_grid;
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}
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