ZSM: include song tuning in export

src/engine/zsm.cpp

@@ -116,6 +116,10 @@ void DivZSM::writeYM(unsigned char a, unsigned char v) {
   }
 }
 
+void DivZSM::writeSync(unsigned char a, unsigned char v) {
+  return syncCache.push_back(DivRegWrite(a,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
@@ -126,7 +130,7 @@ void DivZSM::writePSG(unsigned char a, unsigned char v) {
   } else if (a==68) {
     // Sync event
     numWrites++;
-    return syncCache.push_back(v);
+    return writeSync(0x00,v);
   } else if (a>=64) {
     return writePCM(a-64,v);
   }
@@ -390,15 +394,18 @@ void DivZSM::flushWrites() {
     }
   }
   n=0;
-  while (n<(long)syncCache.size()) { // we have one or more sync events to write
-    int writes=syncCache.size()-n;
-    w->writeC(ZSM_EXT);
-    if (writes>ZSM_SYNC_MAX_WRITES) writes=ZSM_SYNC_MAX_WRITES;
-    w->writeC(ZSM_EXT_SYNC|(writes<<1));
-    for (; writes>0; writes--) {
-      w->writeC(0x00); // 0x00 = Arbitrary sync message
-      w->writeC(syncCache[n++]);
+  for (DivRegWrite& write: syncCache) {
+    if (n%ZSM_SYNC_MAX_WRITES==0) {
+      w->writeC(ZSM_EXT);
+      if (syncCache.size()-n>ZSM_SYNC_MAX_WRITES) {
+        w->writeC((unsigned char)ZSM_EXT_SYNC|(ZSM_SYNC_MAX_WRITES<<1));
+      } else {
+        w->writeC((unsigned char)ZSM_EXT_SYNC|((syncCache.size()-n)<<1));
+      }
     }
+    n++;
+    w->writeC(write.addr);
+    w->writeC(write.val);
   }
   syncCache.clear();
   numWrites=0;

src/engine/zsm.h

@@ -63,7 +63,7 @@ class DivZSM {
     std::vector<unsigned char> pcmData;
     std::vector<unsigned char> pcmCache;
     std::vector<S_pcmInst> pcmInsts;
-    std::vector<unsigned char> syncCache;
+    std::vector<DivRegWrite> syncCache;
     int loopOffset;
     int numWrites;
     int ticks;
@@ -78,6 +78,7 @@ class DivZSM {
     void writeYM(unsigned char a, unsigned char v);
     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 tick(int numticks = 1);
     void setLoopPoint();
     SafeWriter* finish();

src/engine/zsmOps.cpp

@@ -107,6 +107,16 @@ SafeWriter* DivEngine::saveZSM(unsigned int zsmrate, bool loop) {
     // TODO: incorporate the Furnace meta-command for init data and filter
     //       out writes to otherwise-unused channels.
   }
+  // Indicate the song's tuning as a sync meta-event
+  // specified in terms of how many 1/256th semitones
+  // the song is offset from standard A-440 tuning.
+  // This is mainly to benefit visualizations in players
+  // for non-standard tunings so that they can avoid
+  // displaying the entire song held in pitch bend.
+  // Tunings offsets that exceed a half semitone
+  // will simply be represented in a different key
+  signed char tuningoffset=(signed char)round(3072*(log(song.tuning/440.0)/log(2)));
+  zsm.writeSync(0x01,tuningoffset);
 
   while (!done) {
     if (loopPos==-1) {