ZSM: add optimize for size toggle

src/engine/engine.h

@@ -605,7 +605,7 @@ class DivEngine {
     // - -2 to add a whole loop of trailing
     SafeWriter* saveVGM(bool* sysToExport=NULL, bool loop=true, int version=0x171, bool patternHints=false, bool directStream=false, int trailingTicks=-1);
     // dump to ZSM.
-    SafeWriter* saveZSM(unsigned int zsmrate=60, bool loop=true);
+    SafeWriter* saveZSM(unsigned int zsmrate=60, bool loop=true, bool optimize=true);
     // dump command stream.
     SafeWriter* saveCommand(bool binary=false);
     // export to an audio file

src/engine/zsm.cpp

@@ -66,6 +66,8 @@ void DivZSM::init(unsigned int rate) {
   // Channel masks
   ymMask=0;
   psgMask=0;
+  // Optimize writes
+  optimize=false;
 }
 
 int DivZSM::getoffset() {
@@ -121,9 +123,6 @@ void DivZSM::writeSync(unsigned char a, unsigned char v) {
 }
 
 void DivZSM::writePSG(unsigned char a, unsigned char v) {
-  // TODO: suppress writes to PSG voice that is not audible (volume=0)
-  // ^ Let's leave these alone, ZSMKit has a feature that can benefit
-  // from silent channels.
   if (a>=69) {
     logD("ZSM: ignoring VERA PSG write a=%02x v=%02x",a,v);
     return;
@@ -213,6 +212,10 @@ void DivZSM::setLoopPoint() {
   }
 }
 
+void DivZSM::setOptimize(bool o) {
+  optimize = o;
+}
+
 SafeWriter* DivZSM::finish() {
   tick(0); // flush any pending writes / ticks
   flushTicks(); // flush ticks in case there were no writes pending
@@ -278,6 +281,11 @@ void DivZSM::flushWrites() {
   flushTicks(); // only flush ticks if there are writes pending.
   for (unsigned char i=0; i<64; i++) {
     if (psgState[psg_NEW][i]==psgState[psg_PREV][i]) continue;
+    // if optimize=true, suppress writes to PSG voices that are not audible (volume=0 or R+L=0)
+    // ZSMKit has a feature that can benefit from having silent channels
+    // updated, so this is something that can be toggled off or on for export
+    if (optimize && i%4!=2 && (psgState[psg_NEW][(i&0x3c)+2]&0x3f)==0) continue; // vol
+    if (optimize && i%4!=2 && (psgState[psg_NEW][(i&0x3c)+2]&0xc0)==0) continue; // R+L
     psgState[psg_PREV][i]=psgState[psg_NEW][i];
     w->writeC(i);
     w->writeC(psgState[psg_NEW][i]);

src/engine/zsm.h

@@ -70,6 +70,7 @@ class DivZSM {
     int tickRate;
     int ymMask;
     int psgMask;
+    bool optimize;
   public:
     DivZSM();
     ~DivZSM();
@@ -79,6 +80,7 @@ class DivZSM {
     void writePSG(unsigned char a, unsigned char v);
     void writePCM(unsigned char a, unsigned char v);
     void writeSync(unsigned char a, unsigned char v);
+    void setOptimize(bool o);
     void tick(int numticks = 1);
     void setLoopPoint();
     SafeWriter* finish();

src/engine/zsmOps.cpp

@@ -26,7 +26,7 @@
 constexpr int MASTER_CLOCK_PREC=(sizeof(void*)==8)?8:0;
 constexpr int MASTER_CLOCK_MASK=(sizeof(void*)==8)?0xff:0;
 
-SafeWriter* DivEngine::saveZSM(unsigned int zsmrate, bool loop) {
+SafeWriter* DivEngine::saveZSM(unsigned int zsmrate, bool loop, bool optimize) {
   int VERA=-1;
   int YM=-1;
   int IGNORED=0;
@@ -118,6 +118,9 @@ SafeWriter* DivEngine::saveZSM(unsigned int zsmrate, bool loop) {
   // by nature of overflowing the signed char value
   signed char tuningoffset=(signed char)(round(3072*(log(song.tuning/440.0)/log(2))))&0xff;
   zsm.writeSync(0x01,tuningoffset);
+  // Set optimize flag, which mainly buffers PSG writes
+  // whenever the channel is silent
+  zsm.setOptimize(optimize);
 
   while (!done) {
     if (loopPos==-1) {

src/gui/gui.cpp

@@ -4108,6 +4108,8 @@ bool FurnaceGUI::loop() {
             }
             ImGui::Checkbox("loop",&zsmExportLoop);
             ImGui::SameLine();
+            ImGui::Checkbox("optimize size",&zsmExportOptimize);
+            ImGui::SameLine();
             if (ImGui::Button("Begin Export")) {
               openFileDialog(GUI_FILE_EXPORT_ZSM);
               ImGui::CloseCurrentPopup();
@@ -5067,7 +5069,7 @@ bool FurnaceGUI::loop() {
               break;
             }
             case GUI_FILE_EXPORT_ZSM: {
-              SafeWriter* w=e->saveZSM(zsmExportTickRate,zsmExportLoop);
+              SafeWriter* w=e->saveZSM(zsmExportTickRate,zsmExportLoop,zsmExportOptimize);
               if (w!=NULL) {
                 FILE* f=ps_fopen(copyOfName.c_str(),"wb");
                 if (f!=NULL) {
@@ -6799,6 +6801,7 @@ FurnaceGUI::FurnaceGUI():
   displayExporting(false),
   vgmExportLoop(true),
   zsmExportLoop(true),
+  zsmExportOptimize(true),
   vgmExportPatternHints(false),
   vgmExportDirectStream(false),
   displayInsTypeList(false),

src/gui/gui.h

@@ -1324,7 +1324,7 @@ class FurnaceGUI {
   std::vector<String> availRenderDrivers;
   std::vector<String> availAudioDrivers;
 
-  bool quit, warnQuit, willCommit, edit, modified, displayError, displayExporting, vgmExportLoop, zsmExportLoop, vgmExportPatternHints;
+  bool quit, warnQuit, willCommit, edit, modified, displayError, displayExporting, vgmExportLoop, zsmExportLoop, zsmExportOptimize, vgmExportPatternHints;
   bool vgmExportDirectStream, displayInsTypeList;
   bool portrait, injectBackUp, mobileMenuOpen, warnColorPushed;
   bool wantCaptureKeyboard, oldWantCaptureKeyboard, displayMacroMenu;