1 files changed, 59 insertions, 0 deletions
diff --git a/src/pcm_volume.h b/src/pcm_volume.h
new file mode 100644
index 000000000..eb3f8d6ee
--- /dev/null
+++ b/src/pcm_volume.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2003-2009 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef PCM_VOLUME_H
+#define PCM_VOLUME_H
+
+#include "pcm_prng.h"
+
+#include <stdint.h>
+
+enum {
+	/** this value means "100% volume" */
+	PCM_VOLUME_1 = 1000,
+};
+
+struct audio_format;
+
+/**
+ * Converts a float value (0.0 = silence, 1.0 = 100% volume) to an
+ * integer volume value (1000 = 100%).
+ */
+static inline int
+pcm_float_to_volume(float volume)
+{
+	return volume * PCM_VOLUME_1 + 0.5;
+}
+
+static inline int
+pcm_dither(void)
+{
+	static unsigned long state;
+	uint32_t r;
+
+	r = state = prng(state);
+
+	return (r & 511) - ((r >> 9) & 511);
+}
+
+void
+pcm_volume(char *buffer, int bufferSize,
+	   const struct audio_format *format,
+	   int volume);
+
+#endif