FPS-Counter copied, more stuff done

SDL_FPSCounter.c

@@ -0,0 +1,51 @@
+#include "SDL_FPSCounter.h"
+
+#include <SDL3/SDL.h>
+#include <stdlib.h>
+
+int SDL_CreateFPSCounter(SDL_FPSCounter* counter, uint32_t window_length)
+{
+	counter->window = malloc(sizeof(uint64_t) * window_length);
+	if (counter->window == NULL) {
+		SDL_OutOfMemory();
+		return -1;
+	}
+	memset(counter->window, 0, window_length * sizeof(uint64_t));
+	counter->frequency = SDL_GetPerformanceFrequency();
+	counter->window_index = 0;
+	counter->window_length = window_length;
+
+	return EXIT_SUCCESS;
+}
+
+void SDL_DestroyFPSCounter(SDL_FPSCounter* counter)
+{
+	free(counter->window);
+	memset(counter, 0, sizeof *counter);
+}
+
+int SDL_FPSCounterTick(SDL_FPSCounter* counter)
+{
+	counter->window[counter->window_index] = SDL_GetPerformanceCounter();
+	counter->window_index++;
+	counter->window_index = counter->window_index % counter->window_length;
+
+	return EXIT_SUCCESS;
+}
+
+uint64_t SDL_FPSCounterFPS(SDL_FPSCounter* counter)
+{
+	uint64_t last = counter->window[counter->window_index];
+	uint64_t current;
+	uint64_t acc_difference = 0;
+
+	for (uint32_t i = (counter->window_index + 1) % counter->window_length; i != counter->window_index; i = (i + 1) % counter->window_length) {
+		current = counter->window[i];
+		acc_difference += current - last;
+
+		last = current;
+	}
+
+	uint64_t average_difference = acc_difference / (counter->window_length - 1);
+	return counter->frequency / average_difference;
+}