From 4c629d77d9bd67e9861f578d89957b3cf1472aa8 Mon Sep 17 00:00:00 2001
From: Vito Caputo <vcaputo@pengaru.com>
Date: Sun, 5 Nov 2023 15:31:59 -0800
Subject: til_stream: add til_audio_context_t to til_stream_t

Preliminary means of making the audio context available to
modules.
---
 src/main.c       |  2 +-
 src/til_stream.c | 22 +++++++++++++++++++++-
 src/til_stream.h |  4 +++-
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/main.c b/src/main.c
index 70f83e2..daf1b24 100644
--- a/src/main.c
+++ b/src/main.c
@@ -487,7 +487,7 @@ int main(int argc, const char *argv[])
 		exit_if((r = til_audio_open(audio_ops, setup.audio_setup, &rototiller.audio)) < 0,
 			"unable to open audio: %s", strerror(-r));
 
-		exit_if(!(rototiller.stream = til_stream_new()),
+		exit_if(!(rototiller.stream = til_stream_new(rototiller.audio)),
 			"unable to create root stream");
 
 		exit_if(!fps_setup(),
diff --git a/src/til_stream.c b/src/til_stream.c
index 5b9b59c..72dedb6 100644
--- a/src/til_stream.c
+++ b/src/til_stream.c
@@ -96,12 +96,14 @@ typedef struct til_stream_t {
 	unsigned			frame;
 	const til_stream_hooks_t	*hooks;
 	void				*hooks_context;
+	til_audio_context_t		*audio_context;
 	til_stream_pipe_t		*pipe_buckets[TIL_STREAM_PIPE_BUCKETS_COUNT];
 	til_stream_module_context_t	*module_context_buckets[TIL_STREAM_CTXT_BUCKETS_COUNT];
 } til_stream_t;
 
 
-til_stream_t * til_stream_new(void)
+/* the caller must ensure audio_context persists, til_stream_free() will not free it */
+til_stream_t * til_stream_new(til_audio_context_t *audio_context)
 {
 	til_stream_t	*stream;
 
@@ -110,6 +112,7 @@ til_stream_t * til_stream_new(void)
 		return NULL;
 
 	pthread_mutex_init(&stream->mutex, NULL);
+	stream->audio_context = audio_context;
 
 	return stream;
 }
@@ -207,6 +210,23 @@ int til_stream_unset_hooks(til_stream_t *stream, const til_stream_hooks_t *hooks
 }
 
 
+/* An audio context is just a simple singleton per stream, nothing fancy currently.
+ * Any module that wants to produce audio just calls til_stream_get_audio_context()
+ * on the stream, and til_audio_queue() against that context if non-NULL.  When
+ * the context is NULL audio-producing code should just not do anything.
+ *
+ * Nothing is done currently to prevent multiple modules from queueing audio and
+ * making an awful mess, this will probably get improved in the future.  It's just
+ * up to the user/setup to not arrange multiple audio-generating modules on the
+ * same stream.
+ */
+til_audio_context_t * til_stream_get_audio_context(til_stream_t *stream)
+{
+	assert(stream);
+
+	return stream->audio_context;
+}
+
 /* Taps the key-named type-typed pipe on the supplied stream.
  * If this is the first use of the pipe on this stream, new pipe will be created.
  * If the pipe exists on this stream, and the type/n_elems match, existing pipe will be used as-is.
diff --git a/src/til_stream.h b/src/til_stream.h
index e7b92e6..d72b139 100644
--- a/src/til_stream.h
+++ b/src/til_stream.h
@@ -24,6 +24,7 @@
 #include "til_module_context.h"
 #include "til_setup.h"
 
+typedef struct til_audio_context_t til_audio_context_t;
 typedef struct til_stream_t til_stream_t;
 typedef struct til_stream_module_context_t til_stream_module_context_t;
 typedef struct til_stream_pipe_t til_stream_pipe_t;
@@ -44,13 +45,14 @@ typedef struct til_stream_hooks_t {
 	void (*pipe_dtor)(void *context, til_stream_t *stream, const void *owner, const void *owner_foo, const char *parent_path, const til_tap_t *tap);	/* called immediately *after* pipe "destroyed" (withdrawn from stream) */
 } til_stream_hooks_t;
 
-til_stream_t * til_stream_new(void);
+til_stream_t * til_stream_new(til_audio_context_t *audio_context);
 til_stream_t * til_stream_free(til_stream_t *stream);
 void til_stream_end(til_stream_t *stream);
 int til_stream_active(til_stream_t *stream);
 void til_stream_start_frame(til_stream_t *stream);
 int til_stream_set_hooks(til_stream_t *stream, const til_stream_hooks_t *hooks, void *context);
 int til_stream_unset_hooks(til_stream_t *stream, const til_stream_hooks_t *hooks);
+til_audio_context_t * til_stream_get_audio_context(til_stream_t *stream);
 
 /* bare interface for non-module-context owned taps */
 int til_stream_tap(til_stream_t *stream, const void *owner, const void *owner_foo, const char *parent_path, uint32_t parent_hash, const til_tap_t *tap);
-- 
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