initial commit: this looks interesting and gives me a headache

there's still a lot to be done with this code, but hey, it displays an
animation that looks interesting, so i decided to do a git init and
conserve it here for posterity.

Makefile

@@ -0,0 +1,18 @@
+CC = gcc
+COMPILERFLAGS = -Wall -std=c99
+
+COMPILERFLAGS += `sdl-config --cflags`
+LIBPATH = `sdl-config --libs`
+
+All: main
+
+%: %.c
+	$(CC) $(COMPILERFLAGS) $(LIBPATH) $(FRAMEWORK) $^ -o $@
+
+main: main.c
+
+run: main
+	./main
+
+clean:
+	rm main

main.c

@@ -0,0 +1,96 @@
+#include <SDL.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+const int CFG_WIDTH = 512;
+const int CFG_HEIGHT = 512;
+
+SDL_Surface* screen;
+
+static bool init_sdl() {
+    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
+        fprintf(stderr, "Unable to init SDL: %s\n", SDL_GetError());
+        return false;
+    }
+    screen = SDL_SetVideoMode(CFG_WIDTH, CFG_HEIGHT, 32, SDL_HWSURFACE);
+    if (!screen) {
+        fprintf(stderr, "Unable set SDL video mode: %s\n", SDL_GetError());
+        SDL_Quit();
+        return false;
+    }
+    SDL_WM_SetCaption("cell", NULL);
+    return true;
+}
+
+static void teardown_sdl() {
+    SDL_Quit();
+}
+
+static bool process_events() {
+    SDL_Event event;
+    while (SDL_PollEvent(&event)) {
+        if (event.type == SDL_QUIT) return false;
+        if (event.type == SDL_KEYDOWN) {
+            switch(event.key.keysym.sym) {
+              case SDLK_ESCAPE:
+                return false;
+              default:
+                break;
+            }
+        }
+    }
+    return true;
+}
+
+static void display(int cell[CFG_WIDTH][CFG_HEIGHT], SDL_Surface* screen) {
+    Uint32 black = SDL_MapRGB(screen->format, 0, 0, 0);
+    Uint32 white = SDL_MapRGB(screen->format, 255, 255, 255);
+    if (SDL_MUSTLOCK(screen)) {
+        if (SDL_LockSurface(screen) < 0) return;
+    }
+    for (int x = 0; x < CFG_WIDTH; x++) {
+        for (int y = 0; y < CFG_HEIGHT; y++) {
+            Uint32* pixPos = (Uint32 *)screen->pixels + y*screen->pitch/4 + x;
+            *pixPos = cell[x][y]? black : white;
+        }
+    }
+    if (SDL_MUSTLOCK(screen)) SDL_UnlockSurface(screen);
+    SDL_Flip(screen);
+}
+
+static void update(int cell[CFG_WIDTH][CFG_HEIGHT]) {
+    for (int x = 1; x < CFG_WIDTH - 1; x++) {
+        for (int y = 1; y < CFG_HEIGHT - 1; y++) {
+            int sum = 0;
+            for (int i = -1; i < 2; i++) {
+                for (int j = -1; j < 2; j++) {
+                    sum += cell[x + i][y + j];
+                }
+            }
+            if ((sum < 2) || (sum > 4)) {
+                cell[x][y] = 0;
+            } else if (sum == 4) {
+                cell[x][y] = 1;
+            }
+        }
+    }
+}
+
+int main(int argc, char** argv) {
+    if (!init_sdl()) return EXIT_FAILURE;
+    int cell[CFG_WIDTH][CFG_HEIGHT]; // TODO typedef that?
+    srand(0);
+    for (int x = 0; x < CFG_WIDTH; x++) {
+        for (int y = 0; y < CFG_HEIGHT; y++) {
+            cell[x][y] = rand() % 2; //(x + y) % 2;
+        }
+    }
+    while (process_events()) {
+        display(cell, screen);
+        update(cell);
+        usleep(80000);
+    }
+    teardown_sdl();
+    return EXIT_SUCCESS;
+}