1 files changed, 40 insertions, 0 deletions
diff --git a/libs/surfaces/tranzport/slider_gain.h b/libs/surfaces/tranzport/slider_gain.h
new file mode 100644
index 0000000000..1bb497178f
--- /dev/null
+++ b/libs/surfaces/tranzport/slider_gain.h
@@ -0,0 +1,40 @@
+/*
+ *   Copyright (C) 2006 Paul Davis 
+ *   Copyright (C) 2007 Michael Taht
+ *
+ *   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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *  
+ *   */
+
+#ifndef ardour_slider_gain
+#define ardour_slider_gain
+
+static inline double 
+gain_to_slider_position (ARDOUR::gain_t g)
+{
+	if (g == 0) return 0;
+	return pow((6.0*log(g)/log(2.0)+192.0)/198.0, 8.0);
+
+}
+
+static inline ARDOUR::gain_t 
+slider_position_to_gain (double pos)
+{
+	/* XXX Marcus writes: this doesn't seem right to me. but i don't have a better answer ... */
+	if (pos == 0.0) return 0;
+	return pow (2.0,(sqrt(sqrt(sqrt(pos)))*198.0-192.0)/6.0);
+}
+
+#endif