Fix three problems with tuning alpha (#919)

1: The tuning file was mis-interpreting fractions to cents convrersion
2: The tuning file wrapping assumed 2/1 as a last note in one place
3: If you choose a non-scl file you pine for the fjords

This addresses those, and moves us further along #828

src/common/SurgeStorage.cpp

@@ -1190,49 +1190,58 @@ float envelope_rate_linear(float x)
 
 void SurgeStorage::retuneToScale(const Surge::Storage::Scale& s)
 {
-   int scale0 = 48; 
+   int scale0 = 48;  // This is the 1.0 point
    float value0 = 16; 
-
-   for (int i = 0; i < 512; ++i)
-   {
-      int noteBase = i - 256;
-      int distanceFromScale0 = noteBase - scale0 - 1;
-      int turns = 0;
-      float baseValue = value0;
-      while (distanceFromScale0 < 0)
-      {
-         distanceFromScale0 += s.count;
-         baseValue /= 2;
-      }
-      while (distanceFromScale0 >= s.count)
-      {
-         distanceFromScale0 -= s.count;
-         baseValue *= 2;
-      }
-#if DEBUG_SCALE      
-      if ((i>= 254 && i <=258) || ( i >= 302 && i <= 308))
-          std::cout << i << " " << std::setw(5) << noteBase << " or " << i << " D0=" << std::setw(3) << distanceFromScale0
-                    << " PP=" << std::setw(10) << table_pitch[i] 
-                    << " bv=" << std::setw(5) << baseValue
-                    << " sc=" << std::setw(10) << s.tones[distanceFromScale0].floatValue
-                    << " exp=" << std::setw(10) << pow( 2.0f, s.tones[distanceFromScale0].floatValue - 1.0f)
-                    << " sc*bv=" << std::setw(10) << pow( 2.0f, s.tones[distanceFromScale0].floatValue - 1.0f) * baseValue
-                    << " diff=" << std::setw(10) << pow( 2.0f, s.tones[distanceFromScale0].floatValue - 1.0f) * baseValue - table_pitch[i]
-              ;
-#endif
 
-      table_pitch[i] = pow( 2.0f, s.tones[distanceFromScale0].floatValue - 1.0f) * baseValue;
+   float pitches[512];
+   int pos0 = 256 + scale0;
+   pitches[pos0] = 1.0;
+   for (int i=0; i<512; ++i)
+   {
+       int distanceFromScale0 = i - pos0;
+
+       if( distanceFromScale0 == 0 )
+       {
+       }
+       else 
+       {
+           int rounds = (distanceFromScale0-1) / s.count;
+           int thisRound = (distanceFromScale0-1) % s.count;
 
-#if DEBUG_SCALE      
-      if ((i>= 254 && i <=258) || ( i >= 302 && i <= 308))
-         std::cout << " NEWP=" << table_pitch[i] << std::endl;
-#endif
-
+           if( thisRound < 0 )
+           {
+               thisRound += s.count;
+               rounds -= 1;
+           }
+           float mul = pow( s.tones[s.count-1].floatValue, rounds);
+           pitches[i] = s.tones[thisRound].floatValue + rounds * (s.tones[s.count - 1].floatValue - 1.0);
+           float otp = table_pitch[i];
+           table_pitch[i] = pow( 2.0, pitches[i] + 3 );
+
+#if DEBUG_SCALES
+           if( i > 296 && i < 340 )
+               std::cout << "PITCH: i=" << i << " n=" << i - 256 << " r=" << rounds << " t=" << thisRound
+                         << " p=" << pitches[i]
+                         << " t=" << s.tones[thisRound].floatValue
+                         << " tp=" << table_pitch[i]
+                         << " otp=" << otp
+                         << " diff=" << table_pitch[i] - otp
+
+                   //<< " l2p=" << log(otp)/log(2.0)
+                   //<< " l2p-p=" << log(otp)/log(2.0) - pitches[i] - rounds - 3
+                         << std::endl;
+#endif           
+       }
+   }
+
+   for( int i=0; i<512; ++i )
+   {
       table_pitch_inv[i] = 1.f / table_pitch[i];
       table_note_omega[0][i] =
           (float)sin(2 * M_PI * min(0.5, 440 * table_pitch[i] * dsamplerate_os_inv));
       table_note_omega[1][i] =
           (float)cos(2 * M_PI * min(0.5, 440 * table_pitch[i] * dsamplerate_os_inv));
+
    }
 }
 

src/common/Tunings.cpp

@@ -4,6 +4,7 @@
 #include <iostream>
 #include <fstream>
 #include <cstdlib>
+#include <math.h>
 
 /*
  From: http://huygens-fokker.org/scala/scl_format.html
@@ -67,24 +68,28 @@ Surge::Storage::Scale Surge::Storage::readSCLFile(std::string fname)
          {
             t.type = Tone::kToneCents;
             t.cents = atof(line.c_str());
-            t.floatValue = t.cents / 1200.0 + 1.0;
          }
          else
          {
             t.type = Tone::kToneRatio;
             auto slashPos = line.find("/");
             if (slashPos == std::string::npos)
             {
-               t.ratio_d = atoi(line.c_str());
-               t.ratio_n = 1;
+               t.ratio_n = atoi(line.c_str());
+               t.ratio_d = 1;
             }
             else
             {
                t.ratio_n = atoi(line.substr(0, slashPos).c_str());
                t.ratio_d = atoi(line.substr(slashPos + 1).c_str());
             }
-            t.floatValue = 1.0 * t.ratio_n / t.ratio_d;
+
+            // 2^(cents/1200) = n/d
+            // cents = 1200 * log(n/d) / log(2)
+
+            t.cents = 1200 * log(1.0 * t.ratio_n/t.ratio_d) / log(2.0);
          }
+         t.floatValue = t.cents / 1200.0 + 1.0;
          res.tones.push_back(t);
 
          break;
@@ -101,7 +106,7 @@ std::ostream& Surge::Storage::operator<<(std::ostream& os, const Surge::Storage:
       os << t.cents;
    else
       os << t.ratio_n << " / " << t.ratio_d;
-   os << "  (" << t.floatValue << ")";
+   os << "  (f=" << t.floatValue << " c=" << t.cents << ")";
    return os;
 }
 

src/common/gui/SurgeGUIEditor.cpp

@@ -2754,6 +2754,15 @@ void SurgeGUIEditor::showSettingsMenu(CRect &menuRect)
                     {
                         auto cb = [this](std::string sf)
                         {
+                            std::string sfx = ".scl";
+                            if( sf.length() >= sfx.length())
+                            {
+                                if( sf.compare(sf.length() - sfx.length(), sfx.length(), sfx) != 0 )
+                                {
+                                    Surge::UserInteractions::promptError( "Please only select .scl files", "Invalid Choice" );
+                                    return;
+                                }
+                            }
                             auto sc = Surge::Storage::readSCLFile(sf);
                             this->synth->storage.retuneToScale(sc);
                         };

src/headless/main.cpp

@@ -93,7 +93,8 @@ void testTuning()
 {
    SurgeSynthesizer* surge = Surge::Headless::createSurge(44100);
 
-   Surge::Storage::Scale s = Surge::Storage::readSCLFile("/Users/paul/dev/music/scl/05-22.scl");
+   //Surge::Storage::Scale s = Surge::Storage::readSCLFile("/Users/paul/dev/music/test_scl/Q4.scl" );
+   Surge::Storage::Scale s = Surge::Storage::readSCLFile("/Users/paul/dev/music/test_scl/12-flat.scl" );
     std::cout << s;
 
     auto n2f = [surge](int n)
@@ -108,11 +109,11 @@ void testTuning()
    //auto s = Surge::Storage::readSCLFile("/Users/paul/tmp/scl/lumma_12_strangeion.scl");
 
    std::cout << "BEFORE\n";
-   n2f(0); n2f(24); n2f(25); n2f(60); n2f(57); n2f(48);
+   //n2f(0); n2f(24); n2f(25); n2f(60); n2f(57); n2f(48);
    surge->storage.retuneToScale(s);
 
-   std::cout << "AFTER\n";
-   n2f(0); n2f(24); n2f(25);  n2f(60); n2f(57); n2f(48);
+   //std::cout << "AFTER\n";
+   //n2f(0); n2f(24); n2f(25);  n2f(60); n2f(57); n2f(48);
 }
 
 void playSomeBach()