From eae63b218494d3aa077a9ea196abc4c5096e016b Mon Sep 17 00:00:00 2001
From: Drew DeVault <sir@cmpwn.com>
Date: Sun, 12 Dec 2021 13:56:23 +0100
Subject: sdl2::mixer: implement channel playback

---
 cmd/demo/main.ha       |  1 +
 sdl2/mixer/channels.ha | 20 ++++++++++++++++++++
 sdl2/mixer/samples.ha  |  6 ++++++
 3 files changed, 27 insertions(+)
 create mode 100644 sdl2/mixer/channels.ha

diff --git a/cmd/demo/main.ha b/cmd/demo/main.ha
index a5e9e68..e97c433 100644
--- a/cmd/demo/main.ha
+++ b/cmd/demo/main.ha
@@ -74,6 +74,7 @@ fn run() (void | fs::error | sdl2::error) = {
 
 	let sample = mixer::load_file("sample.ogg")?;
 	defer mixer::free_chunk(sample);
+	mixer::play_channel(0, sample, -1)?;
 
 	let state = state {
 		window = win,
diff --git a/sdl2/mixer/channels.ha b/sdl2/mixer/channels.ha
new file mode 100644
index 0000000..4bf4820
--- /dev/null
+++ b/sdl2/mixer/channels.ha
@@ -0,0 +1,20 @@
+use sdl2;
+
+@symbol("Mix_PlayChannelTimed") fn _play_channel_timed(
+	channel: int,
+	sample: *chunk,
+	loops: int,
+	ticks: int,
+) int;
+
+// Play chunk on channel, or if channel is -1, pick the first free unreserved
+// channel. The sample will play for loops+1 number of times, unless stopped by
+// halt, or fade out, or setting a new expiration time of less time than it
+// would have originally taken to play the loops, or closing the mixer.
+export fn play_channel(
+	channel: int,
+	sample: *chunk,
+	loops: int,
+) (void | sdl2::error) = {
+	return sdl2::wrapvoid(_play_channel_timed(channel, sample, loops, -1));
+};
diff --git a/sdl2/mixer/samples.ha b/sdl2/mixer/samples.ha
index 49f1e1e..aaf1ad1 100644
--- a/sdl2/mixer/samples.ha
+++ b/sdl2/mixer/samples.ha
@@ -31,3 +31,9 @@ export fn load_file(src: str) (*chunk | fs::error | sdl2::error) = {
 // chunk after this without loading a new sample to it. Note: It's a bad idea to
 // free a chunk that is still being played... 
 export @symbol("Mix_FreeChunk") fn free_chunk(chunk: *chunk) void;
+
+// Maximum volume for a chunk.
+export def MAX_VOLUME: int = 128; // XXX: SDL_mixer derives this from SDL_MIX_MAXVOLUME
+
+// Sets the chunk volume as specified, returning the previous value.
+export @symbol("Mix_VolumeChunk") fn volume_chunk(chunk: *chunk, volume: int) int;
-- 
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