add effects to change virtual tempo

doc/3-pattern/effects.md

@@ -70,6 +70,9 @@ not all chips support these effects.
   - `xxx` may be from `000` to `3FF`.
 - `F0xx`: **Set BPM.** changes tick rate according to beats per minute. range is `01` to `FF`.
   - ---
+- `FDxx`: **Set virtual tempo numerator.** sets the virtual tempo's numerator to the effect value.
+- `FExx`: **Set virtual tempo denominator.** sets the virtual tempo's denominator to the effect value.
+  - ---
 - `0Bxx`: **Jump to order.** `x` is the order to play after the current row.
   - this marks the end of a loop with order `x` as the loop start.
 - `0Dxx`: **Jump to next pattern.** skips the current row and remainder of current order. `x` is the row at which to start playing the next pattern.

src/engine/engine.cpp

@@ -141,6 +141,10 @@ const char* DivEngine::getEffectDesc(unsigned char effect, int chan, bool notNul
       return "FAxx: Fast volume slide (0y: down; x0: up)";
     case 0xfc:
       return "FCxx: Note release";
+    case 0xfd:
+      return "FDxx: Set virtual tempo numerator";
+    case 0xfe:
+      return "FExx: Set virtual tempo denominator";
     case 0xff:
       return "FFxx: Stop song";
     default:
@@ -1683,7 +1687,7 @@ void DivEngine::playSub(bool preserveDrift, int goalRow) {
       runMidiTime(cycles);
     }
     if (oldOrder!=curOrder) break;
-    if (ticks-((tempoAccum+curSubSong->virtualTempoN)/MAX(1,curSubSong->virtualTempoD))<1 && curRow>=goalRow) break;
+    if (ticks-((tempoAccum+virtualTempoN)/MAX(1,virtualTempoD))<1 && curRow>=goalRow) break;
   }
   for (int i=0; i<song.systemLen; i++) disCont[i].dispatch->setSkipRegisterWrites(false);
   if (goal>0 || goalRow>0) {
@@ -2121,6 +2125,8 @@ void DivEngine::reset() {
   extValue=0;
   extValuePresent=0;
   speeds=curSubSong->speeds;
+  virtualTempoN=curSubSong->virtualTempoN;
+  virtualTempoD=curSubSong->virtualTempoD;
   firstTick=false;
   shallStop=false;
   shallStopSched=false;
@@ -2368,6 +2374,21 @@ float DivEngine::getCurHz() {
   return divider;
 }
 
+short DivEngine::getVirtualTempoN() {
+  return virtualTempoN;
+}
+
+short DivEngine::getVirtualTempoD() {
+  return virtualTempoD;
+}
+
+void DivEngine::virtualTempoChanged() {
+  BUSY_BEGIN;
+  virtualTempoN=curSubSong->virtualTempoN;
+  virtualTempoD=curSubSong->virtualTempoD;
+  BUSY_END;
+}
+
 int DivEngine::getTotalSeconds() {
   return totalSeconds;
 }

src/engine/engine.h

@@ -442,6 +442,7 @@ class DivEngine {
   int curMidiTimePiece, curMidiTimeCode;
   unsigned char extValue, pendingMetroTick;
   DivGroovePattern speeds;
+  short virtualTempoN, virtualTempoD;
   short tempoAccum;
   DivStatusView view;
   DivHaltPositions haltOn;
@@ -891,6 +892,13 @@ class DivEngine {
     // get current Hz
     float getCurHz();
 
+    // get virtual tempo
+    short getVirtualTempoN();
+    short getVirtualTempoD();
+
+    // tell engine about virtual tempo changes
+    void virtualTempoChanged();
+
     // get time
     int getTotalTicks(); // 1/1000000th of a second
     int getTotalSeconds();
@@ -1334,6 +1342,8 @@ class DivEngine {
       curMidiTimeCode(0),
       extValue(0),
       pendingMetroTick(0),
+      virtualTempoN(150),
+      virtualTempoD(150),
       tempoAccum(0),
       view(DIV_STATUS_NOTHING),
       haltOn(DIV_HALT_NONE),

src/engine/playback.cpp

@@ -487,6 +487,12 @@ void DivEngine::processRow(int i, bool afterDelay) {
             if (effectVal>0) speeds.val[0]=effectVal;
           }
           break;
+        case 0xfd: // virtual tempo num
+          if (effectVal>0) virtualTempoN=effectVal;
+          break;
+        case 0xfe: // virtual tempo den
+          if (effectVal>0) virtualTempoD=effectVal;
+          break;
         case 0x0b: // change order
           if (changeOrd==-1 || song.jumpTreatment==0) {
             changeOrd=effectVal;
@@ -1442,9 +1448,9 @@ bool DivEngine::nextTick(bool noAccum, bool inhibitLowLat) {
       subticks=tickMult;
 
       if (stepPlay!=1) {
-        tempoAccum+=(skipping && curSubSong->virtualTempoN<curSubSong->virtualTempoD)?curSubSong->virtualTempoD:curSubSong->virtualTempoN;
+        tempoAccum+=(skipping && virtualTempoN<virtualTempoD)?virtualTempoD:virtualTempoN;
-        while (tempoAccum>=curSubSong->virtualTempoD) {
+        while (tempoAccum>=virtualTempoD) {
-          tempoAccum-=curSubSong->virtualTempoD;
+          tempoAccum-=virtualTempoD;
           if (--ticks<=0) {
             ret=endOfSong;
             if (shallStopSched) {
@@ -1693,7 +1699,7 @@ void DivEngine::runMidiClock(int totalCycles) {
     if (hl<=0.0) hl=4.0;
     double timeBase=curSubSong->timeBase+1;
     double speedSum=0;
-    double vD=curSubSong->virtualTempoD;
+    double vD=virtualTempoD;
     for (int i=0; i<MIN(16,speeds.len); i++) {
       speedSum+=speeds.val[i];
     }
@@ -1701,7 +1707,7 @@ void DivEngine::runMidiClock(int totalCycles) {
     if (timeBase<1.0) timeBase=1.0;
     if (speedSum<1.0) speedSum=1.0;
     if (vD<1) vD=1;
-    double bpm=((24.0*divider)/(timeBase*hl*speedSum))*(double)curSubSong->virtualTempoN/vD;
+    double bpm=((24.0*divider)/(timeBase*hl*speedSum))*(double)virtualTempoN/vD;
     if (bpm<1.0) bpm=1.0;
     int increment=got.rate*pow(2,MASTER_CLOCK_PREC)/(bpm);
 

src/engine/vgmOps.cpp

@@ -2424,7 +2424,7 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
   while (!done) {
     if (loopPos==-1) {
       if (loopOrder==curOrder && loopRow==curRow) {
-        if ((ticks-((tempoAccum+curSubSong->virtualTempoN)/curSubSong->virtualTempoD))<=0) {
+        if ((ticks-((tempoAccum+virtualTempoN)/virtualTempoD))<=0) {
           writeLoop=true;
         }
       }

src/gui/gui.cpp

@@ -4446,7 +4446,7 @@ bool FurnaceGUI::loop() {
           info="| Groove";
         }
 
-        info+=fmt::sprintf(" @ %gHz (%g BPM) ",e->getCurHz(),calcBPM(e->getSpeeds(),e->getCurHz(),e->curSubSong->virtualTempoN,e->curSubSong->virtualTempoD));
+        info+=fmt::sprintf(" @ %gHz (%g BPM) ",e->getCurHz(),calcBPM(e->getSpeeds(),e->getCurHz(),e->getVirtualTempoN(),e->getVirtualTempoD()));
 
         if (settings.orderRowsBase) {
           info+=fmt::sprintf("| Order %.2X/%.2X ",playOrder,e->curSubSong->ordersLen-1);

src/gui/speed.cpp

@@ -171,6 +171,7 @@ void FurnaceGUI::drawSpeed(bool asChild) {
       if (ImGui::InputScalar("##VTempoN",ImGuiDataType_S16,&e->curSubSong->virtualTempoN,&_ONE,&_TEN)) { MARK_MODIFIED
         if (e->curSubSong->virtualTempoN<1) e->curSubSong->virtualTempoN=1;
         if (e->curSubSong->virtualTempoN>255) e->curSubSong->virtualTempoN=255;
+        e->virtualTempoChanged();
       }
       if (ImGui::IsItemHovered()) {
         ImGui::SetTooltip("Numerator");
@@ -180,6 +181,7 @@ void FurnaceGUI::drawSpeed(bool asChild) {
       if (ImGui::InputScalar("##VTempoD",ImGuiDataType_S16,&e->curSubSong->virtualTempoD,&_ONE,&_TEN)) { MARK_MODIFIED
         if (e->curSubSong->virtualTempoD<1) e->curSubSong->virtualTempoD=1;
         if (e->curSubSong->virtualTempoD>255) e->curSubSong->virtualTempoD=255;
+        e->virtualTempoChanged();
       }
       if (ImGui::IsItemHovered()) {
         ImGui::SetTooltip("Denominator (set to base tempo)");