From 1a5c085aa2bb15d46d3bf07a86da73193f538e86 Mon Sep 17 00:00:00 2001
From: Vesa <contact.diizy@nbl.fi>
Date: Fri, 26 Dec 2014 19:31:16 +0200
Subject: [PATCH 1/2] Faster dbv/linear conversions, separate safe functions
 for when the extra safety (0/inf handling) is needed

---
 include/lmms_math.h | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/include/lmms_math.h b/include/lmms_math.h
index 7cde29153..4ab9b3471 100644
--- a/include/lmms_math.h
+++ b/include/lmms_math.h
@@ -239,10 +239,10 @@ static inline float linearToLogScale( float min, float max, float value )
 
 
 
-//! @brief Converts linear amplitude (0-1.0) to dBV scale. 
+//! @brief Converts linear amplitude (0-1.0) to dBV scale. Handles zeroes as -inf.
 //! @param amp Linear amplitude, where 1.0 = 0dBV. 
 //! @return Amplitude in dBV. -inf for 0 amplitude.
-static inline float ampToDbv( float amp )
+static inline float safeAmpToDbv( float amp )
 {
 	return amp == 0.0f
 		? -INFINITY
@@ -250,10 +250,10 @@ static inline float ampToDbv( float amp )
 }
 
 
-//! @brief Converts dBV-scale to linear amplitude with 0dBV = 1.0
+//! @brief Converts dBV-scale to linear amplitude with 0dBV = 1.0. Handles infinity as zero.
 //! @param dbv The dBV value to convert: all infinites are treated as -inf and result in 0
 //! @return Linear amplitude
-static inline float dbvToAmp( float dbv )
+static inline float safeDbvToAmp( float dbv )
 {
 	return isinff( dbv )
 		? 0.0f
@@ -261,6 +261,24 @@ static inline float dbvToAmp( float dbv )
 }
 
 
+//! @brief Converts linear amplitude (>0-1.0) to dBV scale. 
+//! @param amp Linear amplitude, where 1.0 = 0dBV. ** Must be larger than zero! **
+//! @return Amplitude in dBV. 
+static inline float ampToDbv( float amp )
+{
+	return log10f( amp ) * 20.0f;
+}
+
+
+//! @brief Converts dBV-scale to linear amplitude with 0dBV = 1.0
+//! @param dbv The dBV value to convert. ** Must be a real number - not inf/nan! **
+//! @return Linear amplitude
+static inline float dbvToAmp( float dbv )
+{
+	return exp10f( dbv * 0.05f );
+}
+
+
 
 //! returns 1.0f if val >= 0.0f, -1.0 else
 static inline float sign( float val ) 

From 44a2455429bf7fe03a09b15f54ba03df9716a2a4 Mon Sep 17 00:00:00 2001
From: Vesa <contact.diizy@nbl.fi>
Date: Fri, 26 Dec 2014 19:33:48 +0200
Subject: [PATCH 2/2] Correct type in macros

---
 include/lmms_math.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/lmms_math.h b/include/lmms_math.h
index 4ab9b3471..d1a9dcc79 100644
--- a/include/lmms_math.h
+++ b/include/lmms_math.h
@@ -48,10 +48,10 @@ using namespace std;
 #define _isinff(x) isinf(x)
 #endif
 #ifndef exp10
-#define exp10(x) pow( 10, x )
+#define exp10(x) pow( 10.0, x )
 #endif
 #ifndef exp10f
-#define exp10f(x) powf( 10, x )
+#define exp10f(x) powf( 10.0f, x )
 #endif
 #endif