Add sdl_hints:add_callback/3 function

This also sets up esdl2 to start accepting callbacks.
The module/process esdl2_callbacks must always be running
for that purpose, so esdl2 was made an OTP application
instead of a simple library.

Implementation of the rest of SDL_hints will follow in
subsequent commits.

1 files changed, 35 insertions, 0 deletions

diff --git a/c_src/internal.c b/c_src/internal.c
new file mode 100644
index 0000000..0c58476
--- /dev/null
+++ b/c_src/internal.c
@@ -0,0 +1,35 @@
+// Copyright (c) 2015, Loïc Hoguin <[email protected]>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+#include "esdl2.h"
+
+// @todo Make thread-safe.
+
+// register_callback_process
+
+ErlNifPid callback_process;
+
+NIF_FUNCTION(register_callback_process)
+{
+	BADARG_IF(!enif_self(env, &callback_process));
+
+	return atom_ok;
+}
+
+// get_callback_process
+
+ErlNifPid* get_callback_process()
+{
+	return &callback_process;
+}