Add FPS rendering on top

C/include/ascii.h

@@ -7,13 +7,13 @@
 #define ASCII_CHARS_DEFAULT " .:-=+*#%@"
 
 typedef struct {
-  int brightness;
-  int contrast;
-  int invert;
-  int color;
-  int edges;
-  int dither;
-  const char *charset;
+  int brightness;      /* additive offset: -128..128       */
+  int contrast;        /* percent, 100 = no change         */
+  int invert;          /* flip brightness->charset mapping */
+  int color;           /* ANSI truecolor output            */
+  int edges;           /* Sobel edge detection             */
+  int dither;          /* Floyd-Steinberg dithering        */
+  const char *charset; /* NULL = ASCII_CHARS_DEFAULT  */
 } ascii_opts_t;
 
 // Convert YUYV raw data to grayscale
@@ -28,4 +28,7 @@ int grayscale_to_ascii(const uint8_t *gray, const uint8_t *rgb, int src_w,
                        int src_h, int dst_w, int dst_h, char *out,
                        size_t out_size, const ascii_opts_t *opts);
 
+// Overlay FPS box
+void overlay_fps_box(int dst_w, double fps, int color_enabled);
+
 #endif

C/include/thread_sharing.h

@@ -1,17 +1,22 @@
+#ifndef THREAD_SHARING_H
+
 #include <pthread.h>
 #include <stdint.h>
 #include "ascii.h"
 
 typedef struct {
-  uint8_t *buf[2]; // Duble buffer
-  int width, height;
-  int ascii_w, ascii_h;
-  int ready_idx;
-  int has_frame;
+  uint8_t         *buf[2];           // Double buffer
+  int             width, height;
+  int             ascii_w, ascii_h;
+  int             ready_idx;
+  int             has_frame;
   pthread_mutex_t lock;
-  pthread_cond_t cond;
-  volatile int stop;
-
-  ascii_opts_t opts;
+  pthread_cond_t  cond;
+  volatile int    stop;
+  ascii_opts_t    opts;
 } shared_frame_t;
 
+void *capture_thread(void *arg);
+void *render_thread (void *arg);
+
+#endif

C/include/timing.h

@@ -3,9 +3,19 @@
 
 #include <time.h>
 
+typedef struct {
+  long samples[16]; // frame duration (ns) ring buffer
+  int head;
+  int count;
+} fps_counter_t;
+
 // Initialize framerate control
 void timing_init(int fps);
 
 void timing_sleep(struct timespec *start_time);
 
+void fps_push(fps_counter_t *fc, long elapsed_ns);
+
+double fps_get(const fps_counter_t *fc);
+
 #endif