1 files changed, 144 insertions, 0 deletions
diff --git a/src/mixer/plugins/SoftwareMixerPlugin.cxx b/src/mixer/plugins/SoftwareMixerPlugin.cxx
new file mode 100644
index 000000000..f14766002
--- /dev/null
+++ b/src/mixer/plugins/SoftwareMixerPlugin.cxx
@@ -0,0 +1,144 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "SoftwareMixerPlugin.hxx"
+#include "mixer/MixerInternal.hxx"
+#include "filter/FilterPlugin.hxx"
+#include "filter/FilterRegistry.hxx"
+#include "filter/FilterInternal.hxx"
+#include "filter/plugins/VolumeFilterPlugin.hxx"
+#include "pcm/Volume.hxx"
+#include "config/ConfigData.hxx"
+#include "util/Error.hxx"
+
+#include <assert.h>
+#include <math.h>
+
+static Filter *
+CreateVolumeFilter()
+{
+	return filter_new(&volume_filter_plugin, config_param(),
+			  IgnoreError());
+}
+
+class SoftwareMixer final : public Mixer {
+	Filter *filter;
+
+	/**
+	 * If this is true, then this object "owns" the #Filter
+	 * instance (see above).  It will be set to false by
+	 * software_mixer_get_filter(); after that, the caller will be
+	 * responsible for the #Filter.
+	 */
+	bool owns_filter;
+
+	/**
+	 * The current volume in percent (0..100).
+	 */
+	unsigned volume;
+
+public:
+	SoftwareMixer(MixerListener &_listener)
+		:Mixer(software_mixer_plugin, _listener),
+		 filter(CreateVolumeFilter()),
+		 owns_filter(true),
+		 volume(100)
+	{
+		assert(filter != nullptr);
+	}
+
+	virtual ~SoftwareMixer() {
+		if (owns_filter)
+			delete filter;
+	}
+
+	Filter *GetFilter();
+
+	/* virtual methods from class Mixer */
+	virtual bool Open(gcc_unused Error &error) override {
+		return true;
+	}
+
+	virtual void Close() override {
+	}
+
+	virtual int GetVolume(gcc_unused Error &error) override {
+		return volume;
+	}
+
+	virtual bool SetVolume(unsigned volume, Error &error) override;
+};
+
+static Mixer *
+software_mixer_init(gcc_unused EventLoop &event_loop,
+		    gcc_unused AudioOutput &ao,
+		    MixerListener &listener,
+		    gcc_unused const config_param &param,
+		    gcc_unused Error &error)
+{
+	return new SoftwareMixer(listener);
+}
+
+gcc_const
+static unsigned
+PercentVolumeToSoftwareVolume(unsigned volume)
+{
+	assert(volume <= 100);
+
+	if (volume >= 100)
+		return PCM_VOLUME_1;
+	else if (volume > 0)
+		return pcm_float_to_volume((exp(volume / 25.0) - 1) /
+					   (54.5981500331F - 1));
+	else
+		return 0;
+}
+
+bool
+SoftwareMixer::SetVolume(unsigned new_volume, gcc_unused Error &error)
+{
+	assert(new_volume <= 100);
+
+	volume = new_volume;
+	volume_filter_set(filter, PercentVolumeToSoftwareVolume(new_volume));
+	return true;
+}
+
+const MixerPlugin software_mixer_plugin = {
+	software_mixer_init,
+	true,
+};
+
+inline Filter *
+SoftwareMixer::GetFilter()
+{
+	assert(owns_filter);
+
+	owns_filter = false;
+	return filter;
+}
+
+Filter *
+software_mixer_get_filter(Mixer *mixer)
+{
+	SoftwareMixer *sm = (SoftwareMixer *)mixer;
+	assert(sm->IsPlugin(software_mixer_plugin));
+	return sm->GetFilter();
+}