opal: registers $Ax $Bx affect both channels in 4op

1 files changed, 13 insertions, 4 deletions

diff --git a/src/chips/opal/opal.hpp b/src/chips/opal/opal.hpp
index c383bd5..1aa0c7d 100644
--- a/src/chips/opal/opal.hpp
+++ b/src/chips/opal/opal.hpp
@@ -142,6 +142,7 @@ class Opal {
             uint16_t        GetOctave() const {  return Octave;  }
             uint16_t        GetKeyScaleNumber() const {  return KeyScaleNumber;  }
             uint16_t        GetModulationType() const {  return ModulationType;  }
+            Channel *       GetChannelPair() const {  return ChannelPair;  } /* libADLMIDI */
 
             void            ComputeKeyScaleNumber();
 
@@ -475,20 +476,28 @@ void Opal::Port(uint16_t reg_num, uint8_t val) {
 
         Channel &chan = Chan[chan_num];
 
+        /* libADLMIDI: registers Ax and Cx affect both channels */
+        Channel *chans[2] = {&chan, chan.GetChannelPair()};
+        unsigned numchans = chans[1] ? 2 : 1;
+
         // Do specific registers
         switch (reg_num & 0xF0) {
 
             // Frequency low
             case 0xA0: {
-                chan.SetFrequencyLow(val);
+                for (unsigned i = 0; i < numchans; ++i) { /* libADLMIDI */
+                    chans[i]->SetFrequencyLow(val);
+                }
                 break;
             }
 
             // Key-on / Octave / Frequency High
             case 0xB0: {
-                chan.SetKeyOn((val & 0x20) != 0);
-                chan.SetOctave(val >> 2 & 7);
-                chan.SetFrequencyHigh(val & 3);
+                for (unsigned i = 0; i < numchans; ++i) { /* libADLMIDI */
+                    chans[i]->SetKeyOn((val & 0x20) != 0);
+                    chans[i]->SetOctave(val >> 2 & 7);
+                    chans[i]->SetFrequencyHigh(val & 3);
+                }
                 break;
             }