Fix NaN when controlling log params with MIDI CC

Fixes #625

source/backend/CarlaBackend.h

@@ -32,6 +32,7 @@
 # define CARLA_BACKEND_START_NAMESPACE namespace CarlaBackend {
 # define CARLA_BACKEND_END_NAMESPACE }
 # define CARLA_BACKEND_USE_NAMESPACE using namespace CarlaBackend;
+# include <algorithm>
 # include <cmath>
 /* Start namespace */
 CARLA_BACKEND_START_NAMESPACE
@@ -1453,7 +1454,12 @@ typedef struct {
         if (value >= 1.0f)
             return max;
 
-        return min * std::pow(max/min, value);
+        float rmin = min;
+
+        if (std::abs(min) < std::numeric_limits<float>::epsilon())
+            rmin = 0.00001f;
+
+        return rmin * std::pow(max/rmin, value);
     }
 #endif /* __cplusplus */
 

source/backend/engine/CarlaEngineData.cpp

@@ -125,7 +125,7 @@ void EngineEvent::fillFromMidiData(const uint8_t size, const uint8_t* const data
         {
             CARLA_SAFE_ASSERT_RETURN(size >= 3,);
 
-            const uint8_t midiValue(carla_fixedValue<uint8_t>(0, 127, data[2])); // ensures 0.0<->1.0 value range
+            const uint8_t midiValue = carla_fixedValue<uint8_t>(0, 127, data[2]); // ensures 0.0<->1.0 value range
 
             ctrl.type  = kEngineControlEventTypeParameter;
             ctrl.param = midiControl;