Rework Transpose Function to use a natural log to calculate proper note.

This removes the For loop effectively cutting CPU usage in half.
Currently the actual behaviour apears to be exactly like that of the old
however it is possible that those values that go higher then the old table
method(more then 6 octaves up for eg.) will behave slightly different.
Thanks go to Kenny Graunke for working most of this out.

SpiralSound/Plugins/TransposePlugin/TransposePlugin.C

@@ -47,7 +47,8 @@ string SpiralPlugin_GetGroupName() {
 
 TransposePlugin::TransposePlugin () :
 m_Amount(0),
-m_Out(0.0)
+m_Out(0.0),
+m_BufferInitialized(false)
 {
     m_PluginInfo.Name = "Transpose";
     m_PluginInfo.Width = 80;
@@ -72,24 +73,55 @@ SpiralGUIType *TransposePlugin::CreateGUI() {
 }
 
 void TransposePlugin::Execute () {
-     int Match [2];
-     for (int n=0; n<m_HostInfo->BUFSIZE; n++) {
-         Match[0]=0;
-         Match[1]=0;
-         for (int i=0; i<2 && InputExists(i); i++) {
-             float Freq, Dif, MinDif = 30000;
-             Freq = GetInputPitch (i, n);
-             for (int c=0; c<131; c++) {
-                 Dif = fabs (NoteTable[c] - Freq);
-                 if (Dif > MinDif) break;
-                 MinDif=Dif;
-                 Match[i]=c;
-             }
-         }
-         if (! InputExists (1)) Match[1] = m_Amount;
-         m_Out = NoteTable [(Match[0] + Match[1]) % 132];
-         SetOutputPitch (0, n, m_Out);
-     }
+	float base=110, transpose=m_Amount;
+	float alpha = 17.312340490667;
+		
+	for (int n=0; n<m_HostInfo->BUFSIZE; n++) 
+	{
+		float input0 = GetInputPitch(0, n);
+		float input1  = GetInputPitch(1, n);
+		
+		if (input0 > 0)
+		{
+			// input's half steps from base of 110 = round(alpha*logf(GetInputPitch(0, n)/110));
+			// cv's half steps from base of 110 = round(alpha*logf(GetInputPitch(1, n)/110));
+
+			if ((!m_BufferInitialized)  || (input0 != m_Buffer[0][0]) || (input1 != m_Buffer[1][0]))
+			{
+				if ((m_BufferInitialized) && (input0 == m_Buffer[0][0]))
+				{
+					base = m_Buffer[0][1];
+				}
+				else if (input0 != base)
+				{
+					base = round(alpha*logf(input0/110));
+				}
+				m_Buffer[0][0] = input0;
+				m_Buffer[0][1] = base;
+
+				if ((m_BufferInitialized) && (input1 == m_Buffer[1][0]))
+				{
+					transpose = m_Buffer[1][1];
+				}
+				else if (InputExists(1)) 
+				{
+					transpose = (input1 > 0)?round(alpha*logf(input1/110)):0;
+				}
+
+				m_Buffer[1][0] = input1;
+				m_Buffer[1][1] = transpose;
+
+				m_BufferInitialized = true;		
+			
+				m_Out = 110*exp2f((base + transpose)/12);
+			}	
+		}
+		else
+		{
+			m_Out = 8.176;	
+		}	
+		SetOutputPitch (0, n, m_Out);
+	}
 }
 
 void TransposePlugin::StreamOut (ostream &s) {

SpiralSound/Plugins/TransposePlugin/TransposePlugin.h

@@ -23,19 +23,22 @@
 #define TransposePLUGIN
 
 class TransposePlugin : public SpiralPlugin {
-   public:
-      TransposePlugin();
-      virtual ~TransposePlugin ();
-      virtual PluginInfo& Initialise (const HostInfo *Host);
-      virtual SpiralGUIType* CreateGUI ();
-      virtual void Execute ();
-      //virtual void ExecuteCommands ();
-      virtual void StreamOut (std::ostream &s);
-      virtual void StreamIn (std::istream &s);
-      int GetAmount () { return m_Amount; }
-   private:
-      int m_Amount;
-      float m_Out;
+public:
+	TransposePlugin();
+	virtual ~TransposePlugin ();
+	virtual PluginInfo& Initialise (const HostInfo *Host);
+	virtual SpiralGUIType* CreateGUI ();
+	virtual void Execute ();
+	//virtual void ExecuteCommands ();
+	virtual void StreamOut (std::ostream &s);
+	virtual void StreamIn (std::istream &s);
+	int GetAmount () { return m_Amount; }
+private:
+	int m_Amount;
+	float m_Out;
+
+      	float m_Buffer[2][2];
+	bool m_BufferInitialized;
 };
 
 #endif