Use signed arithmetics for game logic

This commit is contained in:
hkz 2025-10-13 18:46:08 +02:00
commit f5cfc0f5da

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@ -1,149 +1,149 @@
#include "game_logic.h"
#include "utility.h"
#include <string.h>
static uint8_t game_grid_alpha[GRID_SIDE * GRID_SIDE];
static uint8_t game_grid_beta[GRID_SIDE * GRID_SIDE];
static uint8_t *front_grid = game_grid_alpha;
static uint8_t *back_grid = game_grid_beta;
void swap_grids(void);
void swap_grids(void) {
uint8_t *temp = front_grid;
front_grid = back_grid;
back_grid = temp;
}
uint8_t reset_game(void) {
uint8_t score = 0;
// Clear the back and front grid
memset(back_grid, 0, GRID_SIDE * GRID_SIDE);
memset(front_grid, 0, GRID_SIDE * GRID_SIDE);
// Then add two random tiles
score += (1 << front_grid[add_random_tile() - 1]);
score += (1 << front_grid[add_random_tile() - 1]);
return score;
}
uint8_t *get_front_grid(void) {
return front_grid;
}
uint8_t add_random_tile(void) {
uint16_t rand = lfsr_update();
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")
uint8_t free_tiles = 0;
uint8_t chosen_tile;
for (uint8_t offset = 0; offset < GRID_SIDE * GRID_SIDE; offset++) {
if (!front_grid[offset]) free_tiles++;
}
if(!free_tiles) return 0;
chosen_tile = (rand >> 8) % free_tiles;
for (uint8_t offset = 0; offset < GRID_SIDE * GRID_SIDE; offset++) {
if (!front_grid[offset] && !(chosen_tile--)) {
front_grid[offset] = tile_val;
return offset + 1;
}
}
return 0; // Return 0 if we were not able to place the tile, else we return (offset + 1) to indicate where the tile was placed
}
int8_t step_game(uint8_t dir) {
int8_t done = 0;
uint8_t start_offset;
int8_t column_step;
int8_t row_step;
/*
* UP: scans TOP to BOTTOM, RIGHT to LEFT
* DOWN: scans BOTTOM to TOP, RIGHT to LEFT
* LEFT: scans LEFT to RIGHT, TOP to BOTTOM
* RIGHT: scans RIGHT to LEFT, TOP to BOTTOM
*/
switch(dir) {
case GAME_STEP_UP:
start_offset = GRID_SIDE - 1;
column_step = GRID_SIDE;
row_step = -1;
break;
case GAME_STEP_DOWN:
start_offset = (GRID_SIDE * GRID_SIDE) - 1;
column_step = -GRID_SIDE;
row_step = -1;
break;
case GAME_STEP_LEFT:
start_offset = 0;
column_step = 1;
row_step = GRID_SIDE;
break;
case GAME_STEP_RIGHT:
start_offset = GRID_SIDE - 1;
column_step = -1;
row_step = GRID_SIDE;
break;
};
// Clear the back grid
memset(back_grid, 0, GRID_SIDE * GRID_SIDE);
for (uint8_t row = 0; row < GRID_SIDE; row++) {
for(uint8_t col = 0; col < GRID_SIDE; col++) {
uint8_t current_offset = start_offset + (col * column_step) + (row * row_step);
uint8_t sub_col;
// 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)
for(sub_col = col; sub_col < GRID_SIDE; sub_col++) {
uint8_t sub_col_offset = start_offset + (sub_col * column_step) + (row * row_step);
if(front_grid[sub_col_offset]) {
back_grid[current_offset] = front_grid[sub_col_offset];
front_grid[sub_col_offset] = 0;
break;
}
}
// The value is still 0, we found nothing. On to the next row!
if (!back_grid[current_offset]) break;
// Now search if there is an identical value following this one, so we can merge them
for(; sub_col < GRID_SIDE; sub_col++) {
uint8_t sub_col_offset = start_offset + (sub_col * column_step) + (row * row_step);
if(front_grid[sub_col_offset] == back_grid[current_offset]) {
back_grid[current_offset]++; // Merge them (by increasing the value of the current square and removing the merged one)
front_grid[sub_col_offset] = 0;
done += back_grid[current_offset] == 11 ? 1 : 0;
break;
} else if (front_grid[sub_col_offset]) break;
}
}
}
swap_grids();
return done;
}
uint16_t calculate_score(void) {
uint16_t score = 0;
for(uint8_t offset = 0; offset < GRID_SIDE * GRID_SIDE; offset++) {
if(front_grid[offset]) score += ((uint16_t)1 << front_grid[offset]);
}
return score;
}
#include "game_logic.h"
#include "utility.h"
#include <string.h>
static uint8_t game_grid_alpha[GRID_SIDE * GRID_SIDE];
static uint8_t game_grid_beta[GRID_SIDE * GRID_SIDE];
static uint8_t *front_grid = game_grid_alpha;
static uint8_t *back_grid = game_grid_beta;
void swap_grids(void);
void swap_grids(void) {
uint8_t *temp = front_grid;
front_grid = back_grid;
back_grid = temp;
}
uint8_t reset_game(void) {
uint8_t score = 0;
// Clear the back and front grid
memset(back_grid, 0, GRID_SIDE * GRID_SIDE);
memset(front_grid, 0, GRID_SIDE * GRID_SIDE);
// Then add two random tiles
score += (1 << front_grid[add_random_tile() - 1]);
score += (1 << front_grid[add_random_tile() - 1]);
return score;
}
uint8_t *get_front_grid(void) {
return front_grid;
}
uint8_t add_random_tile(void) {
uint16_t rand = lfsr_update();
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")
uint8_t free_tiles = 0;
uint8_t chosen_tile;
for (int8_t offset = 0; offset < GRID_SIDE * GRID_SIDE; offset++) {
if (!front_grid[offset]) free_tiles++;
}
if(!free_tiles) return 0;
chosen_tile = (rand >> 8) % free_tiles;
for (int8_t offset = 0; offset < GRID_SIDE * GRID_SIDE; offset++) {
if (!front_grid[offset] && !(chosen_tile--)) {
front_grid[offset] = tile_val;
return offset + 1;
}
}
return 0; // Return 0 if we were not able to place the tile, else we return (offset + 1) to indicate where the tile was placed
}
int8_t step_game(uint8_t dir) {
int8_t done = 0;
int8_t start_offset;
int8_t column_step;
int8_t row_step;
/*
* UP: scans TOP to BOTTOM, RIGHT to LEFT
* DOWN: scans BOTTOM to TOP, RIGHT to LEFT
* LEFT: scans LEFT to RIGHT, TOP to BOTTOM
* RIGHT: scans RIGHT to LEFT, TOP to BOTTOM
*/
switch(dir) {
case GAME_STEP_UP:
start_offset = GRID_SIDE - 1;
column_step = GRID_SIDE;
row_step = -1;
break;
case GAME_STEP_DOWN:
start_offset = (GRID_SIDE * GRID_SIDE) - 1;
column_step = -GRID_SIDE;
row_step = -1;
break;
case GAME_STEP_LEFT:
start_offset = 0;
column_step = 1;
row_step = GRID_SIDE;
break;
case GAME_STEP_RIGHT:
start_offset = GRID_SIDE - 1;
column_step = -1;
row_step = GRID_SIDE;
break;
};
// Clear the back grid
memset(back_grid, 0, GRID_SIDE * GRID_SIDE);
for (int8_t row = 0; row < GRID_SIDE; row++) {
for(int8_t col = 0; col < GRID_SIDE; col++) {
uint8_t current_offset = start_offset + (col * column_step) + (row * row_step);
uint8_t sub_col;
// 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)
for(sub_col = col; sub_col < GRID_SIDE; sub_col++) {
uint8_t sub_col_offset = start_offset + (sub_col * column_step) + (row * row_step);
if(front_grid[sub_col_offset]) {
back_grid[current_offset] = front_grid[sub_col_offset];
front_grid[sub_col_offset] = 0;
break;
}
}
// The value is still 0, we found nothing. On to the next row!
if (!back_grid[current_offset]) break;
// Now search if there is an identical value following this one, so we can merge them
for(; sub_col < GRID_SIDE; sub_col++) {
uint8_t sub_col_offset = start_offset + (sub_col * column_step) + (row * row_step);
if(front_grid[sub_col_offset] == back_grid[current_offset]) {
back_grid[current_offset]++; // Merge them (by increasing the value of the current square and removing the merged one)
front_grid[sub_col_offset] = 0;
done += back_grid[current_offset] == 11 ? 1 : 0;
break;
} else if (front_grid[sub_col_offset]) break;
}
}
}
swap_grids();
return done;
}
uint16_t calculate_score(void) {
uint16_t score = 0;
for(uint8_t offset = 0; offset < GRID_SIDE * GRID_SIDE; offset++) {
if(front_grid[offset]) score += ((uint16_t)1 << front_grid[offset]);
}
return score;
}