+/*
+ * This runs inside the use_window() mutex.
+ */
+static int
+really_draw(WINDOW *win, void *arg)
+{
+ DATA *data = (DATA *) arg;
+
+ (void) win;
+ next_j(data->state);
+ data->func(data);
+ refresh();
+ return OK;
+}
+
+static void
+draw_part(void (*func) (DATA *), int state, DATA * data)
+{
+ data->func = func;
+ data->state = state;
+ use_window(stdscr, really_draw, (void *) data);
+ napsome();
+}
+
+/*
+ * Tell the threads that one of them can start work on a new raindrop.
+ * They may all be busy if we're sending requests too rapidly.
+ */
+static int
+put_next_drop(void)
+{
+ pthread_cond_signal(&cond_next_drop);
+ pthread_mutex_unlock(&mutex_next_drop);
+
+ return 0;
+}
+
+/*
+ * Wait until we're assigned the task of drawing a new raindrop.
+ */
+static int
+get_next_drop(void)
+{
+ pthread_mutex_lock(&mutex_next_drop);
+ pthread_cond_wait(&cond_next_drop, &mutex_next_drop);
+
+ return TRUE;
+}
+
+static void *
+draw_drop(void *arg)
+{
+ DATA mydata;
+ int mystats;
+
+ /*
+ * Find myself in the list of threads so we can count the number of loops.
+ */
+ for (mystats = 0; mystats < MAX_THREADS; ++mystats) {
+#if defined(__MINGW32__) && !defined(__WINPTHREADS_VERSION)
+ if (drop_threads[mystats].myself.p == pthread_self().p)
+#else
+ if (drop_threads[mystats].myself == pthread_self())
+#endif
+ break;
+ }
+
+ do {
+ if (mystats < MAX_THREADS)
+ drop_threads[mystats].counter++;
+
+ /*
+ * Make a copy of caller's data. We're cheating for the cases after
+ * the first loop since we still have a pointer into the main thread
+ * to the data which it uses for setting up this thread (but it has
+ * been modified to use different coordinates).
+ */
+ mydata = *(DATA *) arg;
+
+ draw_part(part1, 0, &mydata);
+ draw_part(part2, 1, &mydata);
+ draw_part(part3, 2, &mydata);
+ draw_part(part4, 3, &mydata);
+ draw_part(part5, 4, &mydata);
+ draw_part(part6, 0, &mydata);
+ } while (get_next_drop());
+
+ return NULL;
+}
+
+/*
+ * The description of pthread_create() is misleading, since it implies that
+ * threads will exit cleanly after their function returns.
+ *
+ * Since they do not (and the number of threads is limited by system
+ * resources), make a limited number of threads, and signal any that are
+ * waiting when we want a thread past that limit.
+ */
+static int
+start_drop(DATA * data)
+{
+ int rc;
+
+ if (!used_threads) {
+ /* mutex and condition for signalling thread */
+ pthread_mutex_init(&mutex_next_drop, NULL);
+ pthread_cond_init(&cond_next_drop, NULL);
+ }
+
+ if (used_threads < MAX_THREADS) {
+ rc = pthread_create(&(drop_threads[used_threads].myself),
+ NULL,
+ draw_drop,
+ data);
+ ++used_threads;
+ } else {
+ rc = put_next_drop();
+ }
+ return rc;
+}
+#endif
+
+static int
+get_input(void)
+{
+ return USING_WINDOW(stdscr, wgetch);
+}
+
+int
+main(int argc GCC_UNUSED,
+ char *argv[]GCC_UNUSED)
+{
+ static const char *help[] =
+ {
+ "Commands:",
+ " q/Q exit the program",
+ " s do single-step",
+ " <space> undo single-step",
+ "",
+ 0
+ };
+
+ bool done = FALSE;
+ DATA drop;
+#ifndef USE_PTHREADS
+ DATA last[MAX_DROP];
+#endif
+ int j = 0;
+
+ setlocale(LC_ALL, "");
+
+ CATCHALL(onsig);
+
+ initscr();
+ if (has_colors()) {
+ int bg = COLOR_BLACK;
+ start_color();
+#if HAVE_USE_DEFAULT_COLORS
+ if (use_default_colors() == OK)
+ bg = -1;
+#endif
+ init_pair(1, COLOR_BLUE, (short) bg);
+ init_pair(2, COLOR_CYAN, (short) bg);
+ }
+ nl();
+ noecho();
+ curs_set(0);
+ timeout(0);
+
+#ifndef USE_PTHREADS
+ for (j = MAX_DROP; --j >= 0;) {
+ last[j].x = random_x();
+ last[j].y = random_y();
+ }
+ j = 0;
+#endif
+
+ while (!done) {
+ drop.x = random_x();
+ drop.y = random_y();
+
+#ifdef USE_PTHREADS
+ if (start_drop(&drop) != 0) {
+ beep();
+ }
+#else
+ /*
+ * The non-threaded code draws parts of each drop on each loop.
+ */
+ part1(&drop);
+
+ part2(&last[j]);
+
+ j = next_j(j);
+ part3(&last[j]);
+
+ j = next_j(j);
+ part4(&last[j]);
+
+ j = next_j(j);
+ part5(&last[j]);
+
+ j = next_j(j);
+ part6(&last[j]);
+
+ last[j] = drop;
+#endif
+
+ switch (get_input()) {
+ case ('q'):
+ case ('Q'):
+ done = TRUE;
+ break;
+ case 's':
+ nodelay(stdscr, FALSE);
+ break;
+ case ' ':
+ nodelay(stdscr, TRUE);
+ break;
+#ifdef KEY_RESIZE
+ case (KEY_RESIZE):
+ break;
+#endif
+ case HELP_KEY_1:
+ popup_msg(stdscr, help);
+ break;
+ case ERR:
+ break;
+ default:
+ beep();
+ }
+ napms(50);
+ }
+ curs_set(1);
+ endwin();
+#ifdef USE_PTHREADS
+ printf("Counts per thread:\n");
+ for (j = 0; j < MAX_THREADS; ++j)
+ printf(" %d:%ld\n", j, drop_threads[j].counter);
+#endif
+ ExitProgram(EXIT_SUCCESS);