Add an id field to outputs

All outputs now have a unique integer ID, allocated from a bitfield pool in the
compositor.

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>

src/compositor.c

@@ -2365,6 +2365,9 @@ weston_output_init(struct weston_output *output, struct weston_compositor *c,
 
 	wl_list_init(&output->frame_callback_list);
 
+	output->id = ffs(~output->compositor->output_id_pool) - 1;
+	output->compositor->output_id_pool |= 1 << output->id;
+
 	output->global =
 		wl_display_add_global(c->wl_display, &wl_output_interface,
 				      output, bind_output);
@@ -2393,6 +2396,8 @@ weston_compositor_init(struct weston_compositor *ec, struct wl_display *display)
 	wl_signal_init(&ec->unlock_signal);
 	ec->launcher_sock = weston_environment_get_fd("WESTON_LAUNCHER_SOCK");
 
+	ec->output_id_pool = 0;
+
 	if (!wl_display_add_global(display, &wl_compositor_interface,
 				   ec, compositor_bind))
 		return -1;

src/compositor.h

@@ -73,6 +73,8 @@ enum dpms_enum {
 };
 
 struct weston_output {
+	uint32_t id;
+
 	struct wl_list link;
 	struct wl_global *global;
 	struct weston_compositor *compositor;
@@ -240,6 +242,8 @@ struct weston_compositor {
 
 	struct screenshooter *screenshooter;
 	int launcher_sock;
+
+	uint32_t output_id_pool;
 };
 
 #define MODIFIER_CTRL	(1 << 8)