replay_gain_*: convert to C++

src/ReplayGainInfo.cxx

@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2003-2013 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"
+
+extern "C" {
+#include "replay_gain_info.h"
+}
+
+float
+replay_gain_tuple_scale(const struct replay_gain_tuple *tuple, float preamp, float missing_preamp, bool peak_limit)
+{
+	float scale;
+
+	if (replay_gain_tuple_defined(tuple)) {
+		scale = pow(10.0, tuple->gain / 20.0);
+		scale *= preamp;
+		if (scale > 15.0)
+			scale = 15.0;
+
+		if (peak_limit && scale * tuple->peak > 1.0)
+			scale = 1.0 / tuple->peak;
+	} else
+		scale = missing_preamp;
+
+	return scale;
+}
+
+void
+replay_gain_info_complete(struct replay_gain_info *info)
+{
+	if (!replay_gain_tuple_defined(&info->tuples[REPLAY_GAIN_ALBUM]))
+		info->tuples[REPLAY_GAIN_ALBUM] =
+			info->tuples[REPLAY_GAIN_TRACK];
+}