VGM export: add option to insert pattern change hi

nts

src/engine/engine.h

@@ -472,7 +472,9 @@ class DivEngine {
     // specify system to build ROM for.
     SafeWriter* buildROM(int sys);
     // dump to VGM.
-    SafeWriter* saveVGM(bool* sysToExport=NULL, bool loop=true, int version=0x171);
+    SafeWriter* saveVGM(bool* sysToExport=NULL, bool loop=true, int version=0x171, bool patternHints=false);
+    // dump command stream.
+    SafeWriter* saveCommand(bool binary=false);
     // export to an audio file
     bool saveAudio(const char* path, int loops, DivAudioExportModes mode, double fadeOutTime=0.0);
     // wait for audio export to finish

src/engine/vgmOps.cpp

@@ -802,7 +802,7 @@ void DivEngine::performVGMWrite(SafeWriter* w, DivSystem sys, DivRegWrite& write
   }
 }
 
-SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version) {
+SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool patternHints) {
   if (version<0x150) {
     lastError="VGM version is too low";
     return NULL;
@@ -1795,6 +1795,12 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version) {
   playSub(false);
   size_t tickCount=0;
   bool writeLoop=false;
+  int ord=-1;
+  int exportChans=0;
+  for (int i=0; i<chans; i++) {
+    if (!willExport[dispatchOfChan[i]]) continue;
+    exportChans++;
+  }
   while (!done) {
     if (loopPos==-1) {
       if (loopOrder==curOrder && loopRow==curRow && ticks==1) {
@@ -1820,6 +1826,26 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version) {
         writeLoop=false;
         loopPos=-1;
       }
+    } else {
+      // check for pattern change
+      if (prevOrder!=ord) {
+        logI("registering order change %d on %d",prevOrder, prevRow);
+        ord=prevOrder;
+
+        if (patternHints) {
+          w->writeC(0x67);
+          w->writeC(0x66);
+          w->writeC(0xfe);
+          w->writeI(3+exportChans);
+          w->writeC(0x01);
+          w->writeC(prevOrder);
+          w->writeC(prevRow);
+          for (int i=0; i<chans; i++) {
+            if (!willExport[dispatchOfChan[i]]) continue;
+            w->writeC(curSubSong->orders.ord[i][prevOrder]);
+          }
+        }
+      }
     }
     // get register dumps
     for (int i=0; i<song.systemLen; i++) {

src/gui/gui.cpp

@@ -2901,6 +2901,22 @@ bool FurnaceGUI::loop() {
             ImGui::EndCombo();
           }
           ImGui::Checkbox("loop",&vgmExportLoop);
+          ImGui::Checkbox("add pattern change hints",&vgmExportPatternHints);
+          if (ImGui::IsItemHovered()) {
+            ImGui::SetTooltip(
+              "inserts data blocks on pattern changes.\n"
+              "useful if you are writing a playback routine.\n\n"
+
+              "the format of a pattern change data block is:\n"
+              "67 66 FE ll ll ll ll 01 oo rr pp pp pp ...\n"
+              "- ll: length, a 32-bit little-endian number\n"
+              "- oo: order\n"
+              "- rr: initial row (a 0Dxx effect is able to select a different row)\n"
+              "- pp: pattern index (one per channel)\n\n"
+
+              "pattern indexes are ordered as they appear in the song."
+            );
+          }
           ImGui::Text("systems to export:");
           bool hasOneAtLeast=false;
           for (int i=0; i<e->song.systemLen; i++) {
@@ -3468,7 +3484,7 @@ bool FurnaceGUI::loop() {
               }
               break;
             case GUI_FILE_EXPORT_VGM: {
-              SafeWriter* w=e->saveVGM(willExport,vgmExportLoop,vgmExportVersion);
+              SafeWriter* w=e->saveVGM(willExport,vgmExportLoop,vgmExportVersion,vgmExportPatternHints);
               if (w!=NULL) {
                 FILE* f=ps_fopen(copyOfName.c_str(),"wb");
                 if (f!=NULL) {
@@ -4431,6 +4447,7 @@ FurnaceGUI::FurnaceGUI():
   displayError(false),
   displayExporting(false),
   vgmExportLoop(true),
+  vgmExportPatternHints(false),
   wantCaptureKeyboard(false),
   oldWantCaptureKeyboard(false),
   displayMacroMenu(false),

src/gui/gui.h

@@ -952,7 +952,7 @@ class FurnaceGUI {
   String mmlString[32];
   String mmlStringW;
 
-  bool quit, warnQuit, willCommit, edit, modified, displayError, displayExporting, vgmExportLoop, wantCaptureKeyboard, oldWantCaptureKeyboard, displayMacroMenu;
+  bool quit, warnQuit, willCommit, edit, modified, displayError, displayExporting, vgmExportLoop, vgmExportPatternHints, wantCaptureKeyboard, oldWantCaptureKeyboard, displayMacroMenu;
   bool displayNew, fullScreen, preserveChanPos, wantScrollList, noteInputPoly;
   bool displayPendingIns, pendingInsSingle;
   bool willExport[32];