Game of Life in C

life.c

#include <ncurses.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>

void handle_sigint(int sig) {
	endwin();
	exit(0);
}

struct State {
	int c;
	int width;
	int height;
	int size;
	unsigned int* buffer;
};

struct State empty(struct State s) {
	for (int i = 0 ; i < s.size; i++) {
		s.buffer[i] = 0;
	}
	
	return s;
}

struct State initState(int width, int height) {
	struct State s;
	s.c = 0;
	s.width = width;
	s.height = height;
	s.size = width * height;
	s.buffer = malloc(s.size * sizeof(unsigned int));
	
	s = empty(s);
	
	return s;
}

struct State fillRandom(struct State s, int seed) {
	srand(seed);
	
	for (int i = 0 ; i < s.size; i++) {
		s.buffer[i] = rand() % 2 > 0;
	}
	
	return s;
}

struct State gliderCannon(struct State s) {
	// Gosper's Glider Gun
	s.buffer[1 * s.width + 26] = 1;
	s.buffer[2 * s.width + 24] = 1;
	s.buffer[2 * s.width + 26] = 1;
	
	s.buffer[3 * s.width + 14] = 1;
	s.buffer[3 * s.width + 15] = 1;
	s.buffer[3 * s.width + 22] = 1;
	s.buffer[3 * s.width + 23] = 1;
	s.buffer[3 * s.width + 36] = 1;
	s.buffer[3 * s.width + 37] = 1;
	
	s.buffer[4 * s.width + 13] = 1;
	s.buffer[4 * s.width + 17] = 1;
	s.buffer[4 * s.width + 22] = 1;
	s.buffer[4 * s.width + 23] = 1;
	s.buffer[4 * s.width + 36] = 1;
	s.buffer[4 * s.width + 37] = 1;
	
	
	s.buffer[5 * s.width +  2] = 1;
	s.buffer[5 * s.width +  3] = 1;
	s.buffer[5 * s.width + 12] = 1;
	s.buffer[5 * s.width + 18] = 1;
	s.buffer[5 * s.width + 22] = 1;
	s.buffer[5 * s.width + 23] = 1;
	
	s.buffer[6 * s.width +  2] = 1;
	s.buffer[6 * s.width +  3] = 1;
	s.buffer[6 * s.width + 12] = 1;
	s.buffer[6 * s.width + 16] = 1;
	s.buffer[6 * s.width + 18] = 1;
	s.buffer[6 * s.width + 19] = 1;
	s.buffer[6 * s.width + 24] = 1;
	s.buffer[6 * s.width + 26] = 1;
	
	s.buffer[7 * s.width + 12] = 1;
	s.buffer[7 * s.width + 18] = 1;
	s.buffer[7 * s.width + 26] = 1;
	
	s.buffer[8 * s.width + 13] = 1;
	s.buffer[8 * s.width + 17] = 1;
	
	s.buffer[9 * s.width + 14] = 1;
	s.buffer[9 * s.width + 15] = 1;
	
	return s;
}

struct State simpleOscillator(struct State s) {
	s.buffer[4 * s.width + 2] = 1;
	s.buffer[4 * s.width + 3] = 1;
	s.buffer[4 * s.width + 4] = 1;
	return s;
}

struct State tick(struct State s0, struct State s1) {
	int offsets[] = {
		-s0.width - 1, -s0.width, -s0.width + 1,
		           -1,                        1,
		 s0.width - 1,  s0.width,  s0.width + 1
	};
	
	for (int i = 0; i < s0.size; i++) {
		int alive = 0;
		for (int o = 0; o < 8; o++) {
			int n = (i + offsets[o]) % s0.size;
			if (n < 0) { continue; }
			if (s0.buffer[n]) {
				alive++;
			}
		}
		if (s0.buffer[i]) {
			if (alive < 2) { s1.buffer[i] = 0; continue; }
			if (alive < 4) { s1.buffer[i] = 1; continue; }
			s1.buffer[i] = 0;
		} else {
			if (alive == 3) { s1.buffer[i] = 1; continue; }
			s1.buffer[i] = 0;
		}
	}
	
	return s1;
}

void draw(struct State s) {
	clear();
	
	for (int i = 0; i < s.size; i++) {
		if (s.buffer[i]) {
			mvprintw(i / s.width, i % s.width, "#");
		}
	}
	refresh();
}

struct State loop(struct State s0, struct State s1) {
	draw(s0);
	s1 = tick(s0, s1);
	s0.c++;
	return s1;
}

int main(int argc, char* argv[]) {

	signal(SIGINT, handle_sigint);
	initscr();
	curs_set(0);
	
	int xmax, ymax;
	getmaxyx(stdscr, ymax, xmax);

	struct State s0 = initState(xmax, ymax);
	struct State s1 = initState(xmax, ymax);
	//s0 = fillRandom(s0, 3);
	s0 = gliderCannon(s0);
	//s0 = simpleOscillator(s0);
	
	while(true) {
		s1 = loop(s0, s1);
		struct State temp = s0;
		s0 = s1;
		s1 = temp;
		usleep(20000);
	}
}