properly clean up before exiting

multibrot.c

@@ -18,12 +18,28 @@ typedef struct {
 /* The maximum iteration count. */
 const int max_it = 170;
 
-/* Compute the out-coloring based on the iteration counter. */
+/**
+ * Compute the out-coloring based on the iteration counter.
+ *
+ * Out-coloring means: coloring when a pixel is determined
+ * to be outside of the mandelbrot set.
+ *
+ * @param it iteration counter when diversion was determined.
+ *
+ * @return pixel color
+ */
 pixel_t outcolor(int it) {
   return 0x00010001 * ((it * 0xff) / max_it);
 }
 
-/* "Compute" the in-coloring. */
+/**
+ * "Compute" the in-coloring.
+ *
+ * In-coloring means: coloring when a pixel is determined
+ * to be inside the mandelbrot set.
+ *
+ * @return pixel, i.e. color
+ */
 pixel_t incolor() {
   return 0x00000000;            /* black */
 }
@@ -69,10 +85,14 @@ bitmap_t *mbrot;
 /* Next line to compute. */
 size_t next_y = 0;
 
-/* Mutex for next_y. */
+/* Mutex for accessing next_y. */
 pthread_mutex_t next_y_mutex;
 
-/* Thread to compute mandelbrot. */
+/**
+ * Thread to compute mandelbrot.
+ *
+ * @param arg (not used, but necessary for pthread_create.)
+ */
 void *compmandelbrot(void *arg) {
   size_t y = 0;
   while (y < mbrot->height) {
@@ -93,8 +113,14 @@ void *compmandelbrot(void *arg) {
   pthread_exit(NULL);
 }
 
-/* Write "bitmap" to a PNG file specified by "path"; returns 0 on
+/**
-   success, non-zero on error. */
+ * Writes a bitmap to a PNG file.
+ *
+ * @param bitmap bitmap to save
+ * @param path   PNG file to write to
+ *
+ * @return 0 on success, non-zero on error.
+ */
 static int save_png_to_file(bitmap_t * bitmap, const char *path) {
   FILE *fp;
 
@@ -219,17 +245,19 @@ int main(int argc, char *argv[]) {
     assert(ret == 0);
   }
 
-  /* Save PNG */
+  /* Save PNG. */
   char *file = "multibrot.png";
   ret = save_png_to_file(mbrot, file);
   assert(ret == 0);
 
-  /* Quit. */
+  /* Clean up. */
-  pthread_exit(NULL);
   free(threads);
   free(mbrot->pixels);
   free(mbrot);
   ret = pthread_mutex_destroy(&next_y_mutex);
   assert(ret == 0);
+
+  /* Quit. */
+  pthread_exit(NULL);
   return 0;
 }