improved interruption (SIGINT, CTRL+C) support

* Just like the original LuaJIT interpreter, this will use a hook to automatically
  raise an error from Lua code.
* Unfortunately, as long as Jit compilation is enabled, this cannot reliably work.
  Therefore we still set an `interrupted` flag that must be
  polled from tight loops.
* Instead of polling via applause_push_sample() which gave interruption-support only
  to Stream:play(), we now have a separate checkint() function.
* checkint() should be manually added to all tight loops.
* Stream:foreach() and everthing based on it is now also supporting interruptions
  (via checkint()).
* This internally works via applause_is_interrupted().
  A C function was exposed only because LuaJIT does not support volatile-qualifiers and
  would optimize away reads to the interrupted-flag.
  As a side effect, we can also reset the hook.
* Flags set in signal handlers should be `volatile`.
* Added likely() and unlikely() macros to C code.
* Updated sample.ipynb Jupyter notebook: Everything important is now supported, albeit
  requiring custom ILua patches.

1 files changed, 2 insertions, 1 deletions

diff --git a/applause.h b/applause.h
index c4d9d87..fc01d49 100644
--- a/applause.h
+++ b/applause.h
@@ -2,10 +2,11 @@
 
 enum applause_audio_state {
 	APPLAUSE_AUDIO_OK = 0,
-	APPLAUSE_AUDIO_INTERRUPTED,
 	APPLAUSE_AUDIO_XRUN,
 	APPLAUSE_AUDIO_INVALID_PORT
 };
 
 enum applause_audio_state applause_push_sample(int output_port_id,
                                                double sample_double);
+
+int applause_is_interrupted(void);