audio: Add Pipewire playback/capture sink

src/audio/pipewire/SDL_pipewire.h

@@ -0,0 +1,42 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2021 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "../../SDL_internal.h"
+
+#ifndef SDL_pipewire_h_
+#define SDL_pipewire_h_
+
+#include "../SDL_sysaudio.h"
+#include <pipewire/pipewire.h>
+
+/* Hidden "this" pointer for the audio functions */
+#define _THIS SDL_AudioDevice* this
+
+struct SDL_PrivateAudioData
+{
+  struct pw_thread_loop* loop;
+  struct pw_stream*      stream;
+  struct pw_context*     context;
+
+  Sint32 stride; /* Bytes-per-frame */
+};
+
+#endif /* SDL_pipewire_h_ */