Add FPS counter to SDL title

SDL/main.c

@@ -7,6 +7,17 @@
 #include "gui.h"
 #include "shader.h"
 
+#define str(x) #x
+#define xstr(x) str(x)
+#define title "SameBoy v" xstr(VERSION)
+
+#define FRAME_VALUES 300 // reduce to get averages above shorter time periods
+Uint32 frametimes[FRAME_VALUES];
+Uint32 frametime_last;
+Uint32 frame_count;
+float frames_per_second;
+float fps_min;
+float fps_max;
 
 #ifndef _WIN32
 #define AUDIO_FREQUENCY 96000
@@ -42,6 +53,51 @@ static const GB_model_t sdl_to_internal_model[] =
     [MODEL_AGB] = GB_MODEL_AGB
 };
 
+void fps_init() {
+    // Set all frame times to 0ms.
+    memset(frametimes, 0, sizeof(frametimes));
+    frame_count = 0;
+    frames_per_second = 0;
+    fps_max = 0;
+    fps_min = FLT_MAX;
+    frametime_last = SDL_GetTicks();
+}
+
+/* Source: http://sdl.beuc.net/sdl.wiki/SDL_Average_FPS_Measurement */
+void fps_update() {
+    Uint32 frametimes_index;
+    Uint32 get_ticks;
+    Uint32 count;
+    Uint32 i;
+
+    frametimes_index = frame_count % FRAME_VALUES;
+    get_ticks = SDL_GetTicks();
+    frametimes[frametimes_index] = get_ticks - frametime_last;
+    frametime_last = get_ticks;
+    frame_count++;
+
+    if (frame_count < FRAME_VALUES) {
+        count = frame_count;
+    } else {
+        count = FRAME_VALUES;
+    }
+
+    frames_per_second = 0;
+    for (i = 0; i < count; i++) {
+       frames_per_second += frametimes[i];
+    }
+
+    frames_per_second /= count;
+    frames_per_second = 1000.f / frames_per_second;
+
+    if (frames_per_second < fps_min) fps_min = frames_per_second;
+    if (frames_per_second > fps_max) fps_max = frames_per_second;
+
+    char title_buffer[50];
+    snprintf(title_buffer, sizeof(title_buffer), title " - %.1f FPS (%.1f - %.1f)", frames_per_second, fps_min, fps_max);
+    SDL_SetWindowTitle(window, title_buffer);
+}
+
 void set_filename(const char *new_filename, bool new_should_free)
 {
     if (filename && should_free_filename) {
@@ -224,7 +280,6 @@ static void handle_events(GB_gameboy_t *gb)
                     case SDL_SCANCODE_C:
                         if (event.type == SDL_KEYDOWN && (event.key.keysym.mod & KMOD_CTRL)) {
                             GB_debugger_break(gb);
-                            
                         }
                         break;
 
@@ -269,6 +324,12 @@ static void handle_events(GB_gameboy_t *gb)
                         }
                         break;
 
+                    case SDL_SCANCODE_L:
+                        if (event.key.keysym.mod & MODIFIER) {
+                            fps_init();
+                        }
+                        break;
+
                     default:
                         /* Save states */
                         if (event.key.keysym.scancode >= SDL_SCANCODE_1 && event.key.keysym.scancode <= SDL_SCANCODE_0) {
@@ -324,6 +385,7 @@ static void vblank(GB_gameboy_t *gb)
         clock_mutliplier += 0.1;
         GB_set_clock_multiplier(gb, clock_mutliplier);
     }
+
     if (configuration.blend_frames) {
         render_texture(active_pixel_buffer, previous_pixel_buffer);
         uint32_t *temp = active_pixel_buffer;
@@ -334,6 +396,9 @@ static void vblank(GB_gameboy_t *gb)
     else {
         render_texture(active_pixel_buffer, NULL);
     }
+
+    fps_update();
+
     do_rewind = rewind_down;
     handle_events(gb);
 }
@@ -448,6 +513,8 @@ restart:
     replace_extension(filename, path_length, symbols_path, ".sym");
     GB_debugger_load_symbol_file(&gb, symbols_path);
 
+    fps_init();
+
     /* Run emulation */
     while (true) {
         if (paused || rewind_paused) {
@@ -490,9 +557,7 @@ static void save_configuration(void)
 
 int main(int argc, char **argv)
 {
-#define str(x) #x
+    fprintf(stderr, title "\n");
-#define xstr(x) str(x)
-    fprintf(stderr, "SameBoy v" xstr(VERSION) "\n");
 
     if (argc > 2) {
         fprintf(stderr, "Usage: %s [rom]\n", argv[0]);
@@ -511,7 +576,7 @@ int main(int argc, char **argv)
     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
     SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
 
-    window = SDL_CreateWindow("SameBoy v" xstr(VERSION), SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
+    window = SDL_CreateWindow(title, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
                               160 * 2, 144 * 2, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
     SDL_SetWindowMinimumSize(window, 160, 144);