Added audio playback

Playing music

code/os/audio.h

@@ -0,0 +1,39 @@
+#if !defined(LD_OS_AUDIO_H_)
+#define LD_OS_AUDIO_H_
+
+typedef struct Audio_Data Audio_Data;
+struct Audio_Data {
+	S16 *samples;
+	U32 n_frames;
+};
+
+typedef struct Audio_Track Audio_Track;
+struct Audio_Track {
+	B32 playing;
+
+	Audio_Data *data;
+
+	U32 n_played;
+	U32 next; // to play if playing, free otherwise
+};
+
+typedef struct Audio_Context Audio_Context;
+struct Audio_Context {
+	SDL_AudioStream *stream;
+
+	U32 n_tracks;
+	Audio_Track tracks[16];
+
+	U32 head;
+	U32 free;
+
+	F32 volume;
+
+	U32 n_sounds;
+	Audio_Data *sounds;
+};
+
+function void Audio_Init(M_Arena *arena, Audio_Context *audio, F32 volume);
+function void Audio_Play(Audio_Context *audio, U32 index);
+
+#endif  // LD_OS_AUDIO_H_