add experimental low-latency mode

do not use (yet)!

src/engine/engine.cpp

@@ -2232,6 +2232,7 @@ bool DivEngine::initAudioBackend() {
 
   lowQuality=getConfInt("audioQuality",0);
   forceMono=getConfInt("forceMono",0);
+  lowLatency=getConfInt("lowLatency",0);
   metroVol=(float)(getConfInt("metroVol",100))/100.0f;
   if (metroVol<0.0f) metroVol=0.0f;
   if (metroVol>2.0f) metroVol=2.0f;

src/engine/engine.h

@@ -202,8 +202,9 @@ class DivEngine {
   bool firstTick;
   bool skipping;
   bool midiIsDirect;
+  bool lowLatency;
   int softLockCount;
-  int ticks, curRow, curOrder, remainingLoops, nextSpeed;
+  int subticks, ticks, curRow, curOrder, remainingLoops, nextSpeed;
   double divider;
   int cycles;
   double clockDrift;
@@ -303,6 +304,7 @@ class DivEngine {
     float* oscBuf[2];
     float oscSize;
     int oscReadPos, oscWritePos;
+    int tickMult;
 
     void runExportThread();
     void nextBuf(float** in, float** out, int inChans, int outChans, unsigned int size);
@@ -745,7 +747,9 @@ class DivEngine {
       firstTick(false),
       skipping(false),
       midiIsDirect(false),
+      lowLatency(false),
       softLockCount(0),
+      subticks(0),
       ticks(0),
       curRow(0),
       curOrder(0),
@@ -789,6 +793,7 @@ class DivEngine {
       oscSize(1),
       oscReadPos(0),
       oscWritePos(0),
+      tickMult(1),
       adpcmAMem(NULL),
       adpcmAMemLen(0),
       adpcmBMem(NULL),

src/engine/macroInt.cpp

@@ -19,6 +19,7 @@
 
 #include "macroInt.h"
 #include "instrument.h"
+#include "engine.h"
 
 void DivMacroStruct::doMacro(DivInstrumentMacro& source, bool released) {
   if (finished) {
@@ -51,9 +52,16 @@ void DivMacroInt::next() {
   if (ins==NULL) return;
   // run macros
   // TODO: potentially get rid of list to avoid allocations
-  for (size_t i=0; i<macroListLen; i++) {
-    if (macroList[i]!=NULL && macroSource[i]!=NULL) {
-      macroList[i]->doMacro(*macroSource[i],released);
+  if (--subTick<=0) {
+    if (e==NULL) {
+      subTick=1;
+    } else {
+      subTick=e->tickMult;
+    }
+    for (size_t i=0; i<macroListLen; i++) {
+      if (macroList[i]!=NULL && macroSource[i]!=NULL) {
+        macroList[i]->doMacro(*macroSource[i],released);
+      }
     }
   }
 }
@@ -62,6 +70,10 @@ void DivMacroInt::release() {
   released=true;
 }
 
+void DivMacroInt::setEngine(DivEngine* eng) {
+  e=eng;
+}
+
 #define ADD_MACRO(m,s) \
   macroList[macroListLen]=&m; \
   macroSource[macroListLen++]=&s;

src/engine/macroInt.h

@@ -22,6 +22,8 @@
 
 #include "instrument.h"
 
+class DivEngine;
+
 struct DivMacroStruct {
   int pos;
   int val;
@@ -49,10 +51,12 @@ struct DivMacroStruct {
 };
 
 class DivMacroInt {
+  DivEngine* e;
   DivInstrument* ins;
   DivMacroStruct* macroList[128];
   DivInstrumentMacro* macroSource[128];
   size_t macroListLen;
+  int subTick;
   bool released;
   public:
     // common macro
@@ -102,6 +106,12 @@ class DivMacroInt {
      */
     void next();
 
+    /**
+     * set the engine.
+     * @param the engine
+     */
+    void setEngine(DivEngine* eng);
+
     /**
      * initialize the macro interpreter.
      * @param which an instrument, or NULL.
@@ -115,8 +125,10 @@ class DivMacroInt {
     void notifyInsDeletion(DivInstrument* which);
 
     DivMacroInt():
+      e(NULL),
       ins(NULL),
       macroListLen(0),
+      subTick(0),
       released(false),
       vol(),
       arp(),

src/engine/platform/amiga.cpp

@@ -414,6 +414,7 @@ void* DivPlatformAmiga::getChanState(int ch) {
 void DivPlatformAmiga::reset() {
   for (int i=0; i<4; i++) {
     chan[i]=DivPlatformAmiga::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].ws.setEngine(parent);
     chan[i].ws.init(NULL,32,255);
     filter[0][i]=0;

src/engine/platform/arcade.cpp

@@ -735,6 +735,7 @@ void DivPlatformArcade::reset() {
   }
   for (int i=0; i<8; i++) {
     chan[i]=DivPlatformArcade::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].vol=0x7f;
     chan[i].outVol=0x7f;
   }

src/engine/platform/ay.cpp

@@ -513,6 +513,7 @@ void DivPlatformAY8910::reset() {
   memset(regPool,0,16);
   for (int i=0; i<3; i++) {
     chan[i]=DivPlatformAY8910::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].vol=0x0f;
   }
   if (dumpWrites) {

src/engine/platform/ay8930.cpp

@@ -528,6 +528,7 @@ void DivPlatformAY8930::reset() {
   memset(regPool,0,32);
   for (int i=0; i<3; i++) {
     chan[i]=DivPlatformAY8930::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].vol=31;
     ayEnvPeriod[i]=0;
     ayEnvMode[i]=0;

src/engine/platform/bubsyswsg.cpp

@@ -274,6 +274,7 @@ void DivPlatformBubSysWSG::reset() {
   memset(regPool,0,4*2);
   for (int i=0; i<2; i++) {
     chan[i]=DivPlatformBubSysWSG::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].ws.setEngine(parent);
     chan[i].ws.init(NULL,32,15,false);
   }

src/engine/platform/c64.cpp

@@ -482,6 +482,7 @@ bool DivPlatformC64::getDCOffRequired() {
 void DivPlatformC64::reset() {
   for (int i=0; i<3; i++) {
     chan[i]=DivPlatformC64::Channel();
+    chan[i].std.setEngine(parent);
   }
 
   sid.reset();

src/engine/platform/fds.cpp

@@ -408,6 +408,7 @@ int DivPlatformFDS::getRegisterPoolSize() {
 void DivPlatformFDS::reset() {
   for (int i=0; i<1; i++) {
     chan[i]=DivPlatformFDS::Channel();
+    chan[i].std.setEngine(parent);
   }
   ws.setEngine(parent);
   ws.init(NULL,64,63,false);

src/engine/platform/gb.cpp

@@ -424,6 +424,7 @@ int DivPlatformGB::getRegisterPoolSize() {
 void DivPlatformGB::reset() {
   for (int i=0; i<4; i++) {
     chan[i]=DivPlatformGB::Channel();
+    chan[i].std.setEngine(parent);
   }
   ws.setEngine(parent);
   ws.init(NULL,32,15,false);

src/engine/platform/genesis.cpp

@@ -827,6 +827,7 @@ void DivPlatformGenesis::reset() {
   }
   for (int i=0; i<10; i++) {
     chan[i]=DivPlatformGenesis::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].vol=0x7f;
     chan[i].outVol=0x7f;
   }

src/engine/platform/lynx.cpp

@@ -329,11 +329,11 @@ int DivPlatformLynx::getRegisterPoolSize()
 }
 
 void DivPlatformLynx::reset() {
-
-  mikey = std::make_unique<Lynx::Mikey>( rate );
+  mikey=std::make_unique<Lynx::Mikey>(rate);
 
   for (int i=0; i<4; i++) {
-    chan[i]= DivPlatformLynx::Channel();
+    chan[i]=DivPlatformLynx::Channel();
+    chan[i].std.setEngine(parent);
   }
   if (dumpWrites) {
     addWrite(0xffffffff,0);

src/engine/platform/mmc5.cpp

@@ -348,6 +348,7 @@ float DivPlatformMMC5::getPostAmp() {
 void DivPlatformMMC5::reset() {
   for (int i=0; i<3; i++) {
     chan[i]=DivPlatformMMC5::Channel();
+    chan[i].std.setEngine(parent);
   }
   if (dumpWrites) {
     addWrite(0xffffffff,0);

src/engine/platform/n163.cpp

@@ -625,6 +625,7 @@ void DivPlatformN163::reset() {
   while (!writes.empty()) writes.pop();
   for (int i=0; i<8; i++) {
     chan[i]=DivPlatformN163::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].ws.setEngine(parent);
     chan[i].ws.init(NULL,32,15,false);
   }

src/engine/platform/nes.cpp

@@ -474,6 +474,7 @@ float DivPlatformNES::getPostAmp() {
 void DivPlatformNES::reset() {
   for (int i=0; i<5; i++) {
     chan[i]=DivPlatformNES::Channel();
+    chan[i].std.setEngine(parent);
   }
   if (dumpWrites) {
     addWrite(0xffffffff,0);

src/engine/platform/opl.cpp

@@ -934,6 +934,7 @@ void DivPlatformOPL::reset() {
 
   for (int i=0; i<totalChans; i++) {
     chan[i]=DivPlatformOPL::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].vol=0x3f;
     chan[i].outVol=0x3f;
   }

src/engine/platform/opll.cpp

@@ -756,6 +756,7 @@ void DivPlatformOPLL::reset() {
   }
   for (int i=0; i<11; i++) {
     chan[i]=DivPlatformOPLL::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].vol=15;
     chan[i].outVol=15;
   }

src/engine/platform/pce.cpp

@@ -462,6 +462,7 @@ void DivPlatformPCE::reset() {
   memset(regPool,0,128);
   for (int i=0; i<6; i++) {
     chan[i]=DivPlatformPCE::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].ws.setEngine(parent);
     chan[i].ws.init(NULL,32,31,false);
   }

src/engine/platform/pcspkr.cpp

@@ -327,6 +327,7 @@ int DivPlatformPCSpeaker::getRegisterPoolSize() {
 void DivPlatformPCSpeaker::reset() {
   for (int i=0; i<1; i++) {
     chan[i]=DivPlatformPCSpeaker::Channel();
+    chan[i].std.setEngine(parent);
   }
   if (dumpWrites) {
     addWrite(0xffffffff,0);

src/engine/platform/pet.cpp

@@ -252,6 +252,7 @@ int DivPlatformPET::getRegisterPoolSize() {
 void DivPlatformPET::reset() {
   memset(regPool,0,16);
   chan=Channel();
+  chan.std.setEngine(parent);
 }
 
 bool DivPlatformPET::isStereo() {

src/engine/platform/qsound.cpp

@@ -523,6 +523,7 @@ void* DivPlatformQSound::getChanState(int ch) {
 void DivPlatformQSound::reset() {
   for (int i=0; i<16; i++) {
     chan[i]=DivPlatformQSound::Channel();
+    chan[i].std.setEngine(parent);
   }
   qsound_reset(&chip);
   while(!chip.ready_flag) {

src/engine/platform/saa.cpp

@@ -392,6 +392,7 @@ void DivPlatformSAA1099::reset() {
   }
   for (int i=0; i<6; i++) {
     chan[i]=DivPlatformSAA1099::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].vol=0x0f;
   }
   if (dumpWrites) {

src/engine/platform/segapcm.cpp

@@ -350,6 +350,7 @@ void DivPlatformSegaPCM::reset() {
   memset(regPool,0,256);
   for (int i=0; i<16; i++) {
     chan[i]=DivPlatformSegaPCM::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].vol=0x7f;
     chan[i].outVol=0x7f;
   }

src/engine/platform/sms.cpp

@@ -278,6 +278,7 @@ void* DivPlatformSMS::getChanState(int ch) {
 void DivPlatformSMS::reset() {
   for (int i=0; i<4; i++) {
     chan[i]=DivPlatformSMS::Channel();
+    chan[i].std.setEngine(parent);
   }
   if (dumpWrites) {
     addWrite(0xffffffff,0);

src/engine/platform/swan.cpp

@@ -453,6 +453,7 @@ void DivPlatformSwan::reset() {
     chan[i]=Channel();
     chan[i].vol=15;
     chan[i].pan=0xff;
+    chan[i].std.setEngine(parent);
     chan[i].ws.setEngine(parent);
     chan[i].ws.init(NULL,32,15,false);
     rWrite(0x08+i,0xff);

src/engine/platform/tia.cpp

@@ -294,6 +294,7 @@ void DivPlatformTIA::reset() {
   memset(regPool,0,16);
   for (int i=0; i<2; i++) {
     chan[i]=DivPlatformTIA::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].vol=0x0f;
   }
 }

src/engine/platform/tx81z.cpp

@@ -729,6 +729,7 @@ void DivPlatformTX81Z::reset() {
   }
   for (int i=0; i<8; i++) {
     chan[i]=DivPlatformTX81Z::Channel();
+    chan[i].std.setEngine(parent);
     chan[i].vol=0x7f;
     chan[i].outVol=0x7f;
   }

src/engine/platform/vera.cpp

@@ -125,6 +125,7 @@ void DivPlatformVERA::acquire(short* bufL, short* bufR, size_t start, size_t len
 void DivPlatformVERA::reset() {
   for (int i=0; i<17; i++) {
     chan[i]=Channel();
+    chan[i].std.setEngine(parent);
   }
   psg_reset(psg);
   pcm_reset(pcm);

src/engine/platform/vic20.cpp

@@ -278,6 +278,7 @@ void DivPlatformVIC20::reset() {
   memset(regPool,0,16);
   for (int i=0; i<4; i++) {
     chan[i]=Channel();
+    chan[i].std.setEngine(parent);
   }
   vic_sound_machine_init(vic,rate,chipClock);
   hasWaveWrite=false;

src/engine/platform/vrc6.cpp

@@ -429,6 +429,7 @@ int DivPlatformVRC6::getRegisterPoolSize() {
 void DivPlatformVRC6::reset() {
   for (int i=0; i<3; i++) {
     chan[i]=DivPlatformVRC6::Channel();
+    chan[i].std.setEngine(parent);
   }
   // a poll may be necessary to decide the default
   chan[2].vol=30;

src/engine/platform/x1_010.cpp

@@ -818,6 +818,7 @@ void DivPlatformX1_010::reset() {
   for (int i=0; i<16; i++) {
     chan[i]=DivPlatformX1_010::Channel();
     chan[i].reset();
+    chan[i].std.setEngine(parent);
     chan[i].ws.setEngine(parent);
     chan[i].ws.init(NULL,128,255,false);
   }

src/engine/platform/ym2610.cpp

@@ -1068,6 +1068,7 @@ void DivPlatformYM2610::reset() {
   fm->reset();
   for (int i=0; i<14; i++) {
     chan[i]=DivPlatformYM2610::Channel();
+    chan[i].std.setEngine(parent);
   }
   for (int i=0; i<4; i++) {
     chan[i].vol=0x7f;

src/engine/platform/ym2610b.cpp

@@ -1131,6 +1131,7 @@ void DivPlatformYM2610B::reset() {
   fm->reset();
   for (int i=0; i<16; i++) {
     chan[i]=DivPlatformYM2610B::Channel();
+    chan[i].std.setEngine(parent);
   }
   for (int i=0; i<6; i++) {
     chan[i].vol=0x7f;

src/engine/playback.cpp

@@ -1472,8 +1472,13 @@ void DivEngine::nextRow() {
 bool DivEngine::nextTick(bool noAccum) {
   bool ret=false;
   if (divider<10) divider=10;
+
+  if (lowLatency) {
+    tickMult=1000/divider;
+    if (tickMult<1) tickMult=1;
+  }
   
-  cycles=got.rate*pow(2,MASTER_CLOCK_PREC)/divider;
+  cycles=got.rate*pow(2,MASTER_CLOCK_PREC)/(divider*tickMult);
   clockDrift+=fmod(got.rate*pow(2,MASTER_CLOCK_PREC),(double)divider);
   if (clockDrift>=divider) {
     clockDrift-=divider;
@@ -1499,130 +1504,133 @@ bool DivEngine::nextTick(bool noAccum) {
   }
 
   if (!freelance) {
-    if (stepPlay!=1) if (--ticks<=0) {
-      ret=endOfSong;
-      if (endOfSong) {
-        if (song.loopModality!=2) {
-          playSub(true);
+    if (--subticks<=0) {
+      subticks=tickMult;
+      if (stepPlay!=1) if (--ticks<=0) {
+        ret=endOfSong;
+        if (endOfSong) {
+          if (song.loopModality!=2) {
+            playSub(true);
+          }
         }
+        endOfSong=false;
+        if (stepPlay==2) stepPlay=1;
+        nextRow();
       }
-      endOfSong=false;
-      if (stepPlay==2) stepPlay=1;
-      nextRow();
-    }
-    // process stuff
-    for (int i=0; i<chans; i++) {
-      if (chan[i].rowDelay>0) {
-        if (--chan[i].rowDelay==0) {
-          processRow(i,true);
+      // process stuff
+      for (int i=0; i<chans; i++) {
+        if (chan[i].rowDelay>0) {
+          if (--chan[i].rowDelay==0) {
+            processRow(i,true);
+          }
         }
-      }
-      if (chan[i].retrigSpeed) {
-        if (--chan[i].retrigTick<0) {
-          chan[i].retrigTick=chan[i].retrigSpeed-1;
-          dispatchCmd(DivCommand(DIV_CMD_NOTE_ON,i,DIV_NOTE_NULL));
-          keyHit[i]=true;
+        if (chan[i].retrigSpeed) {
+          if (--chan[i].retrigTick<0) {
+            chan[i].retrigTick=chan[i].retrigSpeed-1;
+            dispatchCmd(DivCommand(DIV_CMD_NOTE_ON,i,DIV_NOTE_NULL));
+            keyHit[i]=true;
+          }
         }
-      }
-      if (!song.noSlidesOnFirstTick || !firstTick) {
-        if (chan[i].volSpeed!=0) {
-          chan[i].volume=(chan[i].volume&0xff)|(dispatchCmd(DivCommand(DIV_CMD_GET_VOLUME,i))<<8);
-          chan[i].volume+=chan[i].volSpeed;
-          if (chan[i].volume>chan[i].volMax) {
-            chan[i].volume=chan[i].volMax;
-            chan[i].volSpeed=0;
-            dispatchCmd(DivCommand(DIV_CMD_VOLUME,i,chan[i].volume>>8));
-          } else if (chan[i].volume<0) {
-            chan[i].volSpeed=0;
-            if (song.legacyVolumeSlides) {
-              chan[i].volume=chan[i].volMax+1;
+        if (!song.noSlidesOnFirstTick || !firstTick) {
+          if (chan[i].volSpeed!=0) {
+            chan[i].volume=(chan[i].volume&0xff)|(dispatchCmd(DivCommand(DIV_CMD_GET_VOLUME,i))<<8);
+            chan[i].volume+=chan[i].volSpeed;
+            if (chan[i].volume>chan[i].volMax) {
+              chan[i].volume=chan[i].volMax;
+              chan[i].volSpeed=0;
+              dispatchCmd(DivCommand(DIV_CMD_VOLUME,i,chan[i].volume>>8));
+            } else if (chan[i].volume<0) {
+              chan[i].volSpeed=0;
+              if (song.legacyVolumeSlides) {
+                chan[i].volume=chan[i].volMax+1;
+              } else {
+                chan[i].volume=0;
+              }
+              dispatchCmd(DivCommand(DIV_CMD_VOLUME,i,chan[i].volume>>8));
             } else {
-              chan[i].volume=0;
+              dispatchCmd(DivCommand(DIV_CMD_VOLUME,i,chan[i].volume>>8));
             }
-            dispatchCmd(DivCommand(DIV_CMD_VOLUME,i,chan[i].volume>>8));
-          } else {
-            dispatchCmd(DivCommand(DIV_CMD_VOLUME,i,chan[i].volume>>8));
           }
         }
-      }
-      if (chan[i].vibratoDepth>0) {
-        chan[i].vibratoPos+=chan[i].vibratoRate;
-        if (chan[i].vibratoPos>=64) chan[i].vibratoPos-=64;
-        switch (chan[i].vibratoDir) {
-          case 1: // up
-            dispatchCmd(DivCommand(DIV_CMD_PITCH,i,chan[i].pitch+(MAX(0,(chan[i].vibratoDepth*vibTable[chan[i].vibratoPos]*chan[i].vibratoFine)>>4)/15)));
-            break;
-          case 2: // down
-            dispatchCmd(DivCommand(DIV_CMD_PITCH,i,chan[i].pitch+(MIN(0,(chan[i].vibratoDepth*vibTable[chan[i].vibratoPos]*chan[i].vibratoFine)>>4)/15)));
-            break;
-          default: // both
-            dispatchCmd(DivCommand(DIV_CMD_PITCH,i,chan[i].pitch+(((chan[i].vibratoDepth*vibTable[chan[i].vibratoPos]*chan[i].vibratoFine)>>4)/15)));
-            break;
-        }
-      }
-      if (!song.noSlidesOnFirstTick || !firstTick) {
-        if ((chan[i].keyOn || chan[i].keyOff) && chan[i].portaSpeed>0) {
-          if (dispatchCmd(DivCommand(DIV_CMD_NOTE_PORTA,i,chan[i].portaSpeed,chan[i].portaNote))==2 && chan[i].portaStop && song.targetResetsSlides) {
-            chan[i].portaSpeed=0;
-            chan[i].oldNote=chan[i].note;
-            chan[i].note=chan[i].portaNote;
-            chan[i].inPorta=false;
-            dispatchCmd(DivCommand(DIV_CMD_LEGATO,i,chan[i].note));
+        if (chan[i].vibratoDepth>0) {
+          chan[i].vibratoPos+=chan[i].vibratoRate;
+          if (chan[i].vibratoPos>=64) chan[i].vibratoPos-=64;
+          switch (chan[i].vibratoDir) {
+            case 1: // up
+              dispatchCmd(DivCommand(DIV_CMD_PITCH,i,chan[i].pitch+(MAX(0,(chan[i].vibratoDepth*vibTable[chan[i].vibratoPos]*chan[i].vibratoFine)>>4)/15)));
+              break;
+            case 2: // down
+              dispatchCmd(DivCommand(DIV_CMD_PITCH,i,chan[i].pitch+(MIN(0,(chan[i].vibratoDepth*vibTable[chan[i].vibratoPos]*chan[i].vibratoFine)>>4)/15)));
+              break;
+            default: // both
+              dispatchCmd(DivCommand(DIV_CMD_PITCH,i,chan[i].pitch+(((chan[i].vibratoDepth*vibTable[chan[i].vibratoPos]*chan[i].vibratoFine)>>4)/15)));
+              break;
           }
         }
-      }
-      if (chan[i].cut>0) {
-        if (--chan[i].cut<1) {
-          chan[i].oldNote=chan[i].note;
-          //chan[i].note=-1;
-          if (chan[i].inPorta && song.noteOffResetsSlides) {
-            chan[i].keyOff=true;
-            chan[i].keyOn=false;
-            if (chan[i].stopOnOff) {
-              chan[i].portaNote=-1;
-              chan[i].portaSpeed=-1;
-              chan[i].stopOnOff=false;
-            }
-            if (disCont[dispatchOfChan[i]].dispatch->keyOffAffectsPorta(dispatchChanOfChan[i])) {
-              chan[i].portaNote=-1;
-              chan[i].portaSpeed=-1;
-              /*if (i==2 && sysOfChan[i]==DIV_SYSTEM_SMS) {
-                chan[i+1].portaNote=-1;
-                chan[i+1].portaSpeed=-1;
-              }*/
-            }
-            dispatchCmd(DivCommand(DIV_CMD_PRE_PORTA,i,false,0));
-            chan[i].scheduledSlideReset=true;
-          }
-          dispatchCmd(DivCommand(DIV_CMD_NOTE_OFF,i));
-        }
-      }
-      if (chan[i].resetArp) {
-        dispatchCmd(DivCommand(DIV_CMD_LEGATO,i,chan[i].note));
-        chan[i].resetArp=false;
-      }
-      if (song.rowResetsArpPos && firstTick) {
-        chan[i].arpStage=-1;
-      }
-      if (chan[i].arp!=0 && !chan[i].arpYield && chan[i].portaSpeed<1) {
-        if (--chan[i].arpTicks<1) {
-          chan[i].arpTicks=song.arpLen;
-          chan[i].arpStage++;
-          if (chan[i].arpStage>2) chan[i].arpStage=0;
-          switch (chan[i].arpStage) {
-            case 0:
+        if (!song.noSlidesOnFirstTick || !firstTick) {
+          if ((chan[i].keyOn || chan[i].keyOff) && chan[i].portaSpeed>0) {
+            if (dispatchCmd(DivCommand(DIV_CMD_NOTE_PORTA,i,chan[i].portaSpeed,chan[i].portaNote))==2 && chan[i].portaStop && song.targetResetsSlides) {
+              chan[i].portaSpeed=0;
+              chan[i].oldNote=chan[i].note;
+              chan[i].note=chan[i].portaNote;
+              chan[i].inPorta=false;
               dispatchCmd(DivCommand(DIV_CMD_LEGATO,i,chan[i].note));
-              break;
-            case 1:
-              dispatchCmd(DivCommand(DIV_CMD_LEGATO,i,chan[i].note+(chan[i].arp>>4)));
-              break;
-            case 2:
-              dispatchCmd(DivCommand(DIV_CMD_LEGATO,i,chan[i].note+(chan[i].arp&15)));
-              break;
+            }
           }
         }
-      } else {
-        chan[i].arpYield=false;
+        if (chan[i].cut>0) {
+          if (--chan[i].cut<1) {
+            chan[i].oldNote=chan[i].note;
+            //chan[i].note=-1;
+            if (chan[i].inPorta && song.noteOffResetsSlides) {
+              chan[i].keyOff=true;
+              chan[i].keyOn=false;
+              if (chan[i].stopOnOff) {
+                chan[i].portaNote=-1;
+                chan[i].portaSpeed=-1;
+                chan[i].stopOnOff=false;
+              }
+              if (disCont[dispatchOfChan[i]].dispatch->keyOffAffectsPorta(dispatchChanOfChan[i])) {
+                chan[i].portaNote=-1;
+                chan[i].portaSpeed=-1;
+                /*if (i==2 && sysOfChan[i]==DIV_SYSTEM_SMS) {
+                  chan[i+1].portaNote=-1;
+                  chan[i+1].portaSpeed=-1;
+                }*/
+              }
+              dispatchCmd(DivCommand(DIV_CMD_PRE_PORTA,i,false,0));
+              chan[i].scheduledSlideReset=true;
+            }
+            dispatchCmd(DivCommand(DIV_CMD_NOTE_OFF,i));
+          }
+        }
+        if (chan[i].resetArp) {
+          dispatchCmd(DivCommand(DIV_CMD_LEGATO,i,chan[i].note));
+          chan[i].resetArp=false;
+        }
+        if (song.rowResetsArpPos && firstTick) {
+          chan[i].arpStage=-1;
+        }
+        if (chan[i].arp!=0 && !chan[i].arpYield && chan[i].portaSpeed<1) {
+          if (--chan[i].arpTicks<1) {
+            chan[i].arpTicks=song.arpLen;
+            chan[i].arpStage++;
+            if (chan[i].arpStage>2) chan[i].arpStage=0;
+            switch (chan[i].arpStage) {
+              case 0:
+                dispatchCmd(DivCommand(DIV_CMD_LEGATO,i,chan[i].note));
+                break;
+              case 1:
+                dispatchCmd(DivCommand(DIV_CMD_LEGATO,i,chan[i].note+(chan[i].arp>>4)));
+                break;
+              case 2:
+                dispatchCmd(DivCommand(DIV_CMD_LEGATO,i,chan[i].note+(chan[i].arp&15)));
+                break;
+            }
+          }
+        } else {
+          chan[i].arpYield=false;
+        }
       }
     }
   }
@@ -1636,7 +1644,7 @@ bool DivEngine::nextTick(bool noAccum) {
     if (stepPlay!=1) {
       if (!noAccum) {
         totalTicksR++;
-        totalTicks+=1000000/divider;
+        totalTicks+=1000000/(divider*tickMult);
       }
       if (totalTicks>=1000000) {
         totalTicks-=1000000;

src/gui/gui.h

@@ -818,6 +818,7 @@ class FurnaceGUI {
     int scrollChangesOrder;
     int oplStandardWaveNames;
     int cursorMoveNoScroll;
+    int lowLatency;
     unsigned int maxUndoSteps;
     String mainFontPath;
     String patFontPath;
@@ -889,6 +890,7 @@ class FurnaceGUI {
       scrollChangesOrder(0),
       oplStandardWaveNames(0),
       cursorMoveNoScroll(0),
+      lowLatency(0),
       maxUndoSteps(100),
       mainFontPath(""),
       patFontPath(""),

src/gui/settings.cpp

@@ -405,6 +405,14 @@ void FurnaceGUI::drawSettings() {
           e->setMetronomeVol(((float)settings.metroVol)/100.0f);
         }
 
+        bool lowLatencyB=settings.lowLatency;
+        if (ImGui::Checkbox("Low-latency mode (experimental!)",&lowLatencyB)) {
+          settings.lowLatency=lowLatencyB;
+        }
+        if (ImGui::IsItemHovered()) {
+          ImGui::SetTooltip("reduces latency by running the engine faster than the tick rate.\nuseful for live playback/jam mode.\n\nwarning: experimental! may produce glitches.\nonly enable if your buffer size is small (10ms or less).");
+        }
+
         bool forceMonoB=settings.forceMono;
         if (ImGui::Checkbox("Force mono audio",&forceMonoB)) {
           settings.forceMono=forceMonoB;
@@ -1600,6 +1608,7 @@ void FurnaceGUI::syncSettings() {
   settings.scrollChangesOrder=e->getConfInt("scrollChangesOrder",0);
   settings.oplStandardWaveNames=e->getConfInt("oplStandardWaveNames",0);
   settings.cursorMoveNoScroll=e->getConfInt("cursorMoveNoScroll",0);
+  settings.lowLatency=e->getConfInt("lowLatency",0);
 
   clampSetting(settings.mainFontSize,2,96);
   clampSetting(settings.patFontSize,2,96);
@@ -1660,6 +1669,7 @@ void FurnaceGUI::syncSettings() {
   clampSetting(settings.scrollChangesOrder,0,1);
   clampSetting(settings.oplStandardWaveNames,0,1);
   clampSetting(settings.cursorMoveNoScroll,0,1);
+  clampSetting(settings.lowLatency,0,1);
 
   // keybinds
   for (int i=0; i<GUI_ACTION_MAX; i++) {
@@ -1747,6 +1757,7 @@ void FurnaceGUI::commitSettings() {
   e->setConf("scrollChangesOrder",settings.scrollChangesOrder);
   e->setConf("oplStandardWaveNames",settings.oplStandardWaveNames);
   e->setConf("cursorMoveNoScroll",settings.cursorMoveNoScroll);
+  e->setConf("lowLatency",settings.lowLatency);
 
   // colors
   for (int i=0; i<GUI_COLOR_MAX; i++) {