From ba4c64adeaa4fed8ac5d8bbd6496567422a0ca79 Mon Sep 17 00:00:00 2001
From: Paul Ferrand <paul@ferrand.cc>
Date: Mon, 23 Dec 2019 18:32:37 +0100
Subject: [PATCH] Readability cleanup

---
 src/sfizz/MathHelpers.h | 73 ++++++++++++++++++++++++++---------------
 src/sfizz/Voice.cpp     | 17 +++-------
 2 files changed, 51 insertions(+), 39 deletions(-)

diff --git a/src/sfizz/MathHelpers.h b/src/sfizz/MathHelpers.h
index 601152e7..23a01211 100644
--- a/src/sfizz/MathHelpers.h
+++ b/src/sfizz/MathHelpers.h
@@ -26,7 +26,7 @@
  * @author Paul Ferrand (paul@ferrand.cc)
  * @brief Contains math helper functions and math constants
  * @version 0.1
- * @date 2019-11-23 
+ * @date 2019-11-23
  */
 #pragma once
 #include <algorithm>
@@ -43,10 +43,10 @@ inline constexpr T min(T op1, T op2, T op3, T op4) { return std::min(op1, std::m
 
 /**
  * @brief Converts db values into power (applies 10**(in/10))
- * 
- * @tparam Type 
- * @param in 
- * @return Type 
+ *
+ * @tparam Type
+ * @param in
+ * @return Type
  */
 template <class Type>
 inline constexpr Type db2pow(Type in)
@@ -56,10 +56,10 @@ inline constexpr Type db2pow(Type in)
 
 /**
  * @brief Converts power values into dB (applies 10log10(in))
- * 
- * @tparam Type 
- * @param in 
- * @return Type 
+ *
+ * @tparam Type
+ * @param in
+ * @return Type
  */
 template <class Type>
 inline constexpr Type pow2db(Type in)
@@ -69,10 +69,10 @@ inline constexpr Type pow2db(Type in)
 
 /**
  * @brief Converts dB values to magnitude (applies 10**(in/20))
- * 
- * @tparam Type 
- * @param in 
- * @return constexpr Type 
+ *
+ * @tparam Type
+ * @param in
+ * @return constexpr Type
  */
 template <class Type>
 inline constexpr Type db2mag(Type in)
@@ -82,10 +82,10 @@ inline constexpr Type db2mag(Type in)
 
 /**
  * @brief Converts magnitude values into dB (applies 20log10(in))
- * 
- * @tparam Type 
- * @param in 
- * @return Type 
+ *
+ * @tparam Type
+ * @param in
+ * @return Type
  */
 template <class Type>
 inline constexpr Type mag2db(Type in)
@@ -95,9 +95,9 @@ inline constexpr Type mag2db(Type in)
 
 /**
  * @brief Global random singletons
- * 
+ *
  * TODO: could be moved into a singleton class holder
- * 
+ *
  */
 namespace Random {
 	static std::random_device randomDevice;
@@ -106,9 +106,9 @@ namespace Random {
 
 /**
  * @brief Converts a midi note to a frequency value
- * 
- * @param noteNumber 
- * @return float 
+ *
+ * @param noteNumber
+ * @return float
  */
 inline float midiNoteFrequency(const int noteNumber)
 {
@@ -117,11 +117,11 @@ inline float midiNoteFrequency(const int noteNumber)
 
 /**
  * @brief Clamps a value between bounds, including the bounds!
- * 
- * @tparam T 
- * @param v 
- * @param lo 
- * @param hi 
+ *
+ * @tparam T
+ * @param v
+ * @param lo
+ * @param hi
  * @return T
  */
 template<class T>
@@ -131,6 +131,25 @@ constexpr T clamp( const T& v, const T& lo, const T& hi )
 	return (v < lo) ? lo : (hi < v) ? hi : v;
 }
 
+template<class T>
+constexpr void incrementAll(T& only)
+{
+    only++;
+}
+
+template<class T, class... Args>
+constexpr void incrementAll(T& first, Args&... rest)
+{
+    first++;
+    incrementAll(rest...);
+}
+
+template<class ValueType>
+constexpr ValueType linearInterpolation(ValueType left, ValueType right, ValueType leftCoeff, ValueType rightCoeff)
+{
+    return left * leftCoeff + right * rightCoeff;
+}
+
 template <class Type>
 constexpr Type pi { 3.141592653589793238462643383279502884 };
 template <class Type>
diff --git a/src/sfizz/Voice.cpp b/src/sfizz/Voice.cpp
index d7800a8f..a7e4a15e 100644
--- a/src/sfizz/Voice.cpp
+++ b/src/sfizz/Voice.cpp
@@ -420,23 +420,16 @@ void sfz::Voice::fillWithData(AudioSpan<float> buffer) noexcept
     auto leftSource = source.getChannel(0);
     if (source.getNumChannels() == 1) {
         while (ind < indices.end()) {
-            *left = leftSource[*ind] * (*leftCoeff) + leftSource[*ind + 1] * (*rightCoeff);
-            left++;
-            ind++;
-            leftCoeff++;
-            rightCoeff++;
+            *left = linearInterpolation(leftSource[*ind], leftSource[*ind + 1], *leftCoeff, *rightCoeff);
+            incrementAll(ind, left, leftCoeff, rightCoeff);
         }
     } else {
         auto right = buffer.getChannel(1);
         auto rightSource = source.getChannel(1);
         while (ind < indices.end()) {
-            *left = leftSource[*ind] * (*leftCoeff) + leftSource[*ind + 1] * (*rightCoeff);
-            *right = rightSource[*ind] * (*leftCoeff) + rightSource[*ind + 1] * (*rightCoeff);
-            left++;
-            right++;
-            ind++;
-            leftCoeff++;
-            rightCoeff++;
+            *left = linearInterpolation(leftSource[*ind], leftSource[*ind + 1], *leftCoeff, *rightCoeff);
+            *right = linearInterpolation(rightSource[*ind], rightSource[*ind + 1], *leftCoeff, *rightCoeff);
+            incrementAll(ind, left, right, leftCoeff, rightCoeff);
         }
     }