ChannelSplit Tests and Corrections (#1480)

1. Add a collection of unit tests to Channel Split mode in
   both MPE and Non-MPE mode

2. From running those tests, fix the bug in non-MPE mode with
   channel mask; and fix the bug with < vs <=

Closes #1476

src/common/SurgeSynthesizer.cpp

@@ -205,7 +205,7 @@ int SurgeSynthesizer::calculateChannelMask(int channel, int key)
    */
    int channelmask = channel;
 
-   if ((channel == 0) || (channel > 2) || mpeEnabled)
+   if ((channel == 0) || (channel > 2) || mpeEnabled || storage.getPatch().scenemode.val.i == sm_chsplit ) 
    {
       switch (storage.getPatch().scenemode.val.i)
       {
@@ -226,7 +226,7 @@ int SurgeSynthesizer::calculateChannelMask(int channel, int key)
             channelmask = 2;
          break;
       case sm_chsplit:
-         if( channel <= ( (int)( storage.getPatch().splitkey.val.i / 8 ) + 1 ) )
+         if( channel < ( (int)( storage.getPatch().splitkey.val.i / 8 ) + 1 ) )
             channelmask = 1;
          else
             channelmask = 2;
@@ -241,7 +241,7 @@ int SurgeSynthesizer::calculateChannelMask(int channel, int key)
        else
            channelmask = 1;
    }
-
+   
    return channelmask;
 }
 

src/headless/Player.cpp

@@ -17,13 +17,13 @@ playerEvents_t makeHoldMiddleC(int forSamples, int withTail)
    return makeHoldNoteFor(60, forSamples, withTail );
 }
 
-playerEvents_t makeHoldNoteFor( int note, int forSamples, int withTail )
+playerEvents_t makeHoldNoteFor( int note, int forSamples, int withTail, int midiChannel )
 {
    playerEvents_t result;
 
    Event on;
    on.type = Event::NOTE_ON;
-   on.channel = 0;
+   on.channel = midiChannel;
    on.data1 = note;
    on.data2 = 100;
    on.atSample = 0;

src/headless/Player.h

@@ -48,7 +48,7 @@ typedef std::vector<Event> playerEvents_t; // We assume these are monotonic in E
  */
 playerEvents_t makeHoldMiddleC(int forSamples, int withTail = 0);
 
-playerEvents_t makeHoldNoteFor(int note, int forSamples, int withTail = 0);
+playerEvents_t makeHoldNoteFor(int note, int forSamples, int withTail = 0, int midiChannel = 0);
 
 playerEvents_t make120BPMCMajorQuarterNoteScale(long sample0 = 0, int sr = 44100);
 

src/headless/UnitTests.cpp

@@ -139,9 +139,11 @@ std::shared_ptr<SurgeSynthesizer> surgeOnSine()
 ** frequency measure (which works great for the sine patch and poorly for others
 ** At one day we could do this with autocorrelation instead but no need now.
 */
-double frequencyForNote( std::shared_ptr<SurgeSynthesizer> surge, int note, int seconds = 2, bool channel = 0 )
+double frequencyForNote( std::shared_ptr<SurgeSynthesizer> surge, int note,
+                         int seconds = 2, bool audioChannel = 0,
+                         int midiChannel = 0 )
 {
-   auto events = Surge::Headless::makeHoldNoteFor( note, 44100 * seconds, 64 );
+   auto events = Surge::Headless::makeHoldNoteFor( note, 44100 * seconds, 64, midiChannel );
    float *buffer;
    int nS, nC;
    Surge::Headless::playAsConfigured( surge.get(), events, &buffer, &nS, &nC );
@@ -156,7 +158,7 @@ double frequencyForNote( std::shared_ptr<SurgeSynthesizer> surge, int note, int
    float *leftTrimmed = new float[nSTrim];
 
    for( int i=0; i<nSTrim; ++i )
-      leftTrimmed[i] = buffer[ (i + start) * 2 + channel ];
+      leftTrimmed[i] = buffer[ (i + start) * 2 + audioChannel ];
 
    // OK so now look for sample times between positive/negative crosses
    int v = -1;
@@ -1432,6 +1434,46 @@ TEST_CASE( "ADSR Envelope Behaviour", "[mod]" )
 }
 
 
+TEST_CASE( "Channel Split Routes on Channel", "[midi]" )
+{
+   auto surge = std::shared_ptr<SurgeSynthesizer>( Surge::Headless::createSurge(44100) );
+   REQUIRE( surge );
+   REQUIRE( surge->loadPatchByPath( "test-data/patches/ChannelSplit-Sin-2OctaveB.fxp", -1, "Test" ) );
+
+   SECTION( "Regular (non-MPE)" )
+   {
+      surge->mpeEnabled = false;
+      for( auto splitChan = 2; splitChan < 14; splitChan ++ )
+      {
+         auto smc = splitChan * 8;
+         surge->storage.getPatch().splitkey.val.i = smc;
+         for( auto mc=0; mc<16; ++mc )
+         {
+            auto fr = frequencyForNote( surge, 69, 2, 0, mc );
+            auto targetfr = mc <= splitChan ? 440 : 440 * 4;
+            REQUIRE( fr == Approx( targetfr ).margin( 0.1 ) );
+         }
+      }
+   }
+
+
+   SECTION( "MPE Enabled" )
+   {
+      surge->mpeEnabled = true;
+      for( auto splitChan = 2; splitChan < 14; splitChan ++ )
+      {
+         auto smc = splitChan * 8;
+         surge->storage.getPatch().splitkey.val.i = smc;
+         for( auto mc=0; mc<16; ++mc )
+         {
+            auto fr = frequencyForNote( surge, 69, 2, 0, mc );
+            auto targetfr = mc <= splitChan ? 440 : 440 * 4;
+            REQUIRE( fr == Approx( targetfr ).margin( 0.1 ) );
+         }
+      }
+   }
+}
+
 
 int runAllTests(int argc, char **argv)
 {