Fix two AEG problems in oversample and 0 rate mode (#1393)

- In 0 rate mode we would improperly skip sectinos nw I have
  fixed the exp timing blowing out the behavior. Do a variety
  of things to skip ahead properly to the first active stage

- The OS AEG had the wrong sample rate. This meant with OS on
  the AEG went twice as fast.

Fix both and close #1389

src/engine/group.cpp

@@ -474,6 +474,8 @@ void Group::onSampleRateChanged()
 
     for (auto &z : zones)
         z->setSampleRate(getSampleRate(), getSampleRateInv());
+
+    this->setHasModulatorsSampleRate(getSampleRate(), getSampleRateInv());
 }
 
 void Group::onProcessorTypeChanged(int w, dsp::processor::ProcessorType t)

src/modulation/has_modulators.h

@@ -45,7 +45,19 @@ static_assert(egsPerGroup == egsPerZone,
               "If this is false you need to template out the count below");
 template <typename T> struct HasModulators
 {
-    HasModulators(T *that) : eg{that, that}, egOS{that, that} {}
+    struct DoubleRate
+    {
+        double sampleRate, sampleRateInv;
+        T *that{nullptr};
+        DoubleRate(T *that) : that(that) { resetRates(); }
+        void resetRates()
+        {
+            sampleRate = that->sampleRate * 2;
+            sampleRateInv = that->sampleRateInv / 2;
+        }
+    } doubleRate;
+
+    HasModulators(T *that) : eg{that, that}, doubleRate{that}, egOS{&doubleRate, &doubleRate} {}
 
     static constexpr uint16_t lfosPerObject{lfosPerZone};
     static constexpr uint16_t egsPerObject{egsPerZone};
@@ -66,14 +78,16 @@ template <typename T> struct HasModulators
         ahdsrenv_t;
 
     typedef sst::basic_blocks::modulators::AHDSRShapedSC<
-        T, blockSize << 1, sst::basic_blocks::modulators::TwentyFiveSecondExp>
+        DoubleRate, (blockSize << 1), sst::basic_blocks::modulators::TwentyFiveSecondExp>
         ahdsrenvOS_t;
 
     ahdsrenv_t eg[egsPerObject];
     ahdsrenvOS_t egOS[egsPerObject];
 
     std::array<bool, lfosPerObject> lfosActive{};
     std::array<bool, egsPerObject> egsActive{};
+
+    void setHasModulatorsSampleRate(double sr, double sri) { doubleRate.resetRates(); }
 };
 } // namespace scxt::modulation::shared
 #endif // SHORTCIRCUITXT_HAS_MODULATORS_H

src/voice/voice.cpp

@@ -794,4 +794,7 @@ void Voice::updateTransportPhasors()
         mul = mul / 2;
     }
 }
+
+void Voice::onSampleRateChanged() { setHasModulatorsSampleRate(samplerate, samplerate_inv); }
+
 } // namespace scxt::voice

src/voice/voice.h

@@ -199,6 +199,8 @@ struct alignas(16) Voice : MoveableOnly<Voice>,
     }
     void release() { isGated = false; }
     void cleanupVoice();
+
+    void onSampleRateChanged() override;
 };
 } // namespace scxt::voice