John Conway's Game of Life - NES
I recently purchased the EverDrive N8 Pro 72pin which allows me to play NES ROMs on my NES opposed to using an emulator. At the time of this writing, I have yet to receive the cartridge but I am preparing for when it arrives!
For this project I decided to try out the NES Lib which are in C. Given my introduction to programming was MS-DOS 16 bit x86 assembly, I find the idea of learning NES's assembly to be a fun challenge.
Screenshots running on the FCEUX emulator
Pinwheel
Pulsar
Glider
Random
Random
Source Code
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include "lib/neslib/neslib.h"
// general vars
static uint8_t spr;
static uint8_t input;
// map vars
#define WIDTH 256
#define HEIGHT 240
#define TILE_SIZE 9
#define TILES_X 15
#define TILES_Y 15
static const uint8_t ALIVE = 1;
static const uint8_t DEAD = 0;
static const uint8_t DX = (WIDTH - (TILES_X * TILE_SIZE)) / 2;
static const uint8_t DY = (HEIGHT - (TILES_Y * TILE_SIZE)) / 2;
static uint8_t i, frame = 0, paused = 0;
static uint8_t x, y;
static uint8_t fg_layer = 0;
static uint8_t bg_layer = 1;
static uint8_t neighbors;
static uint8_t next_state;
static uint8_t layers[2][TILES_Y][TILES_X] = {
{ // https://conwaylife.com/wiki/Pinwheel
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0},
{0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0},
{0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0},
{0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0},
{0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
},
{ // https://conwaylife.com/wiki/Pulsar
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0},
{0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0},
{0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0},
{0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0},
{0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0},
{0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0},
{0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
}
};
/**
* Handle wrap-around.
* e.g.
* TILES_X = 4
* x = 0 -> (0 + 4) % 4 -> 4 % 4 -> 0
* x = 1 -> (1 + 4) % 4 -> 5 % 4 -> 1
* x = 2 -> (2 + 4) % 4 -> 6 % 4 -> 2
* x = 3 -> (3 + 4) % 4 -> 7 % 4 -> 3
* x = 4 -> (4 + 4) % 4 -> 8 % 4 -> 0
*/
uint8_t get_wrap(uint8_t x, uint8_t y) {
return layers[fg_layer][(y + TILES_Y) % TILES_Y][(x + TILES_X) % TILES_X];
}
uint8_t get(uint8_t x, uint8_t y) {
if (x < 0 || x >= TILES_X || y < 0 || y >= TILES_Y) {
return 0;
}
return layers[fg_layer][y][x];
}
uint8_t count_alive_neighbors(uint8_t x, uint8_t y) {
return get(x - 1, y - 1) + get(x, y - 1) + get(x + 1, y - 1) +
get(x - 1, y) + get(x + 1, y) +
get(x - 1, y + 1) + get(x, y + 1) + get(x + 1, y + 1);
}
static void randomize_map() {
for (y = 0; y < TILES_Y; y++) {
for (x = 0; x < TILES_X; x++) {
if (rand8() > 207) {
layers[fg_layer][y][x] = ALIVE;
} else {
layers[fg_layer][y][x] = DEAD;
}
layers[bg_layer][y][x] = DEAD;
}
}
}
static void clear_map() {
for (y = 0; y < TILES_Y; y++) {
for (x = 0; x < TILES_X; x++) {
layers[fg_layer][y][x] = DEAD;
layers[bg_layer][y][x] = DEAD;
}
}
}
/**
* @
* @
* @@@
* [y, x]
*/
void build_glider() {
clear_map();
x = 3;
y = 3;
layers[fg_layer][y + 2][x + 1] = ALIVE; // top
layers[fg_layer][y + 1][x + 2] = ALIVE; // middle
layers[fg_layer][y + 0][x + 0] = ALIVE; // ------
layers[fg_layer][y + 0][x + 1] = ALIVE; // bottom
layers[fg_layer][y + 0][x + 2] = ALIVE; // ------
}
void start_pinwheel() {
fg_layer = 0;
bg_layer = 1;
}
void start_pulsar() {
fg_layer = 1;
bg_layer = 0;
}
const uint8_t sprites_pal[32] = {
0x0f, 0x17, 0x27, 0x37,
0x0f, 0x29, 0x21, 0x31,
0x0f, 0x15, 0x25, 0x35,
0x0f, 0x19, 0x29, 0x39,
0x0f, 0x05, 0x10, 0x10,
0x0f, 0x07, 0x12, 0x14,
0x0f, 0x30, 0x8f, 0x33,
};
static void swap_layers() {
bg_layer = !bg_layer;
fg_layer = !fg_layer;
}
static void handle_input() {
input = pad_trigger(0);
if (input & PAD_A + input & PAD_B) {
randomize_map();
}
if (input & PAD_START) {
paused = !paused;
}
}
static compute_next_state() {
for (y = 0; y < TILES_Y; y++) {
for (x = 0; x < TILES_X; x++) {
neighbors = count_alive_neighbors(x, y);
next_state = layers[fg_layer][y][x]; // default to carry over state
if (layers[fg_layer][y][x] == ALIVE) {
// 1. Any live cell with fewer than two live neighbors dies, as if caused by underpopulation.
// 2. Any live cell with more than three live neighbors dies, as if by overcrowding.
if (neighbors < 2 || neighbors > 3) {
next_state = DEAD;
}
// 3. Any live cell with two or three live neighbors lives on to the next generation.
else {
next_state = ALIVE;
}
} else {
// 4. Any dead cell with exactly three live neighbors becomes a live cell.
if (neighbors == 3) {
next_state = ALIVE;
}
// 5. Else cell remains dead.
else {
next_state = DEAD;
}
}
layers[bg_layer][y][x] = next_state;
}
}
}
static render() {
oam_clear();
spr = 0;
for (y = 0; y < TILES_Y; ++y) {
for (x = 0; x < TILES_X; ++x) {
if (layers[fg_layer][y][x] == ALIVE) {
neighbors = count_alive_neighbors(x, y);
spr = oam_spr(DX + x * TILE_SIZE, DY + y * TILE_SIZE + 8, layers[fg_layer][y][x], neighbors, spr);
}
}
}
}
void main(void) {
//randomize_map();
//build_glider();
start_pinwheel();
//start_pulsar();
pal_spr(sprites_pal); // set palette for sprites
ppu_on_all(); // enable rendering
while (1) {
ppu_wait_frame(); // wait for next TV frame
handle_input();
if (!paused && frame % 2 == 0) {
compute_next_state();
}
render();
if (!paused && frame % 2 == 0) {
swap_layers();
}
++frame;
}
}
NES ROMs
Tool Chain + Build NES File
- cc65
- chr2png
- png2chr
- nsf2data
- test2data
Build Toolchain + NES File
git clone git@github.com:kennycason/game_of_life_nes.git
cd game_of_life_nes
Checkout the cc65 submodule
git submodule update --init --recursive
Build cc65
cd tools/cc65
make
Build the other tools
cd tools
make
Build the NES ROM
make
Open NES ROM with FCEUX NES Emulator
fceux game_of_life.nes
Resources + Referenced Projects
- https://github.com/slembcke/neslib-template
- https://github.com/sebastiandine/openNES-Snake
- http://shiru.untergrund.net/articles/programming_nes_games_in_c.htm
- https://nesdoug.com/
Notes:
- NES limits the number of tiles that can be rendered to the screen. This causes some tiles to disappear between renders. The state is still preserved.
- V2 will use VRAM for better graphics performance.
Arrived
Ninja Turdle