From 4723ed3972a54a4af81908196b3f883a38f31779 Mon Sep 17 00:00:00 2001
From: tildearrow <tildearrow@protonmail.com>
Date: Mon, 17 Oct 2022 14:25:30 -0500
Subject: [PATCH] VGM: experimental direct stream mode for YM2612

---
 src/engine/dispatch.h           |  3 +++
 src/engine/platform/genesis.cpp | 32 +++++++++++++++++++++---------
 src/engine/platform/genesis.h   |  3 ++-
 src/engine/vgmOps.cpp           | 35 +++++++++++++++++++++++++++++++++
 src/main.cpp                    |  9 ++++++++-
 5 files changed, 71 insertions(+), 11 deletions(-)

diff --git a/src/engine/dispatch.h b/src/engine/dispatch.h
index ffd9e247..4c9fb2f2 100644
--- a/src/engine/dispatch.h
+++ b/src/engine/dispatch.h
@@ -264,6 +264,9 @@ struct DivRegWrite {
 struct DivDelayedWrite {
   int time;
   DivRegWrite write;
+  DivDelayedWrite(int t, unsigned int a, unsigned short v):
+    time(t),
+    write(a,v) {}
 };
 
 struct DivDispatchOscBuffer {
diff --git a/src/engine/platform/genesis.cpp b/src/engine/platform/genesis.cpp
index 480ecb44..0eb4aebb 100644
--- a/src/engine/platform/genesis.cpp
+++ b/src/engine/platform/genesis.cpp
@@ -27,11 +27,11 @@
 
 #define IS_REALLY_MUTED(x) (isMuted[x] && (x<5 || !softPCM || (isMuted[5] && isMuted[6])))
 
-void DivPlatformGenesis::processDAC() {
+void DivPlatformGenesis::processDAC(int iRate) {
   if (softPCM) {
     softPCMTimer+=chipClock/576;
-    if (softPCMTimer>rate) {
-      softPCMTimer-=rate;
+    if (softPCMTimer>iRate) {
+      softPCMTimer-=iRate;
 
       int sample=0;
       for (int i=5; i<7; i++) {
@@ -75,14 +75,14 @@ void DivPlatformGenesis::processDAC() {
   } else {
     if (!chan[5].dacReady) {
       chan[5].dacDelay+=32000;
-      if (chan[5].dacDelay>=rate) {
-        chan[5].dacDelay-=rate;
+      if (chan[5].dacDelay>=iRate) {
+        chan[5].dacDelay-=iRate;
         chan[5].dacReady=true;
       }
     }
     if (chan[5].dacMode && chan[5].dacSample!=-1) {
       chan[5].dacPeriod+=chan[5].dacRate;
-      if (chan[5].dacPeriod>=rate) {
+      if (chan[5].dacPeriod>=iRate) {
         DivSample* s=parent->getSample(chan[5].dacSample);
         if (s->samples>0) {
           if (!isMuted[5]) {
@@ -106,7 +106,7 @@ void DivPlatformGenesis::processDAC() {
               rWrite(0x2b,0);
             }
           }
-          while (chan[5].dacPeriod>=rate) chan[5].dacPeriod-=rate;
+          while (chan[5].dacPeriod>=iRate) chan[5].dacPeriod-=iRate;
         } else {
           chan[5].dacSample=-1;
         }
@@ -120,7 +120,7 @@ void DivPlatformGenesis::acquire_nuked(short* bufL, short* bufR, size_t start, s
   static int os[2];
 
   for (size_t h=start; h<start+len; h++) {
-    processDAC();
+    processDAC(rate);
 
     os[0]=0; os[1]=0;
     for (int i=0; i<6; i++) {
@@ -180,7 +180,7 @@ void DivPlatformGenesis::acquire_ymfm(short* bufL, short* bufR, size_t start, si
   ymfm::ym2612::fm_engine* fme=fm_ymfm->debug_engine();
 
   for (size_t h=start; h<start+len; h++) {
-    processDAC();
+    processDAC(rate);
   
     os[0]=0; os[1]=0;
     if (!writes.empty()) {
@@ -237,6 +237,20 @@ void DivPlatformGenesis::acquire(short* bufL, short* bufR, size_t start, size_t
   }
 }
 
+void DivPlatformGenesis::fillStream(std::vector<DivDelayedWrite>& stream, int sRate, size_t len) {
+  while (!writes.empty()) writes.pop_front();
+  for (size_t i=0; i<len; i++) {
+    processDAC(sRate);
+
+    while (!writes.empty()) {
+      QueuedWrite& w=writes.front();
+      stream.push_back(DivDelayedWrite(i,w.addr,w.val));
+      writes.pop_front();
+    }
+  }
+  regWrites.clear();
+}
+
 void DivPlatformGenesis::tick(bool sysTick) {
   for (int i=0; i<(softPCM?7:6); i++) {
     if (i==2 && extMode) continue;
diff --git a/src/engine/platform/genesis.h b/src/engine/platform/genesis.h
index f4b853a8..f3022f55 100644
--- a/src/engine/platform/genesis.h
+++ b/src/engine/platform/genesis.h
@@ -119,12 +119,13 @@ class DivPlatformGenesis: public DivPlatformOPN {
     friend void putDispatchChip(void*,int);
     friend void putDispatchChan(void*,int,int);
 
-    inline void processDAC();
+    inline void processDAC(int iRate);
     void acquire_nuked(short* bufL, short* bufR, size_t start, size_t len);
     void acquire_ymfm(short* bufL, short* bufR, size_t start, size_t len);
   
   public:
     void acquire(short* bufL, short* bufR, size_t start, size_t len);
+    void fillStream(std::vector<DivDelayedWrite>& stream, int sRate, size_t len);
     int dispatch(DivCommand c);
     void* getChanState(int chan);
     DivMacroInt* getChanMacroInt(int ch);
diff --git a/src/engine/vgmOps.cpp b/src/engine/vgmOps.cpp
index 582eafbd..01d01ac8 100644
--- a/src/engine/vgmOps.cpp
+++ b/src/engine/vgmOps.cpp
@@ -948,6 +948,7 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
   bool sampleDir[DIV_MAX_CHANS];
   std::vector<unsigned int> chipVol; 
   std::vector<DivDelayedWrite> delayedWrites[32];
+  std::vector<std::pair<int,DivDelayedWrite>> sortedWrites;
 
   for (int i=0; i<DIV_MAX_CHANS; i++) {
     loopTimer[i]=0;
@@ -1942,8 +1943,42 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
     // check whether we need to loop
     int totalWait=cycles>>MASTER_CLOCK_PREC;
     if (directStream) {
+      // render stream of all chips
       for (int i=0; i<song.systemLen; i++) {
         disCont[i].dispatch->fillStream(delayedWrites[i],44100,totalWait);
+        for (DivDelayedWrite& j: delayedWrites[i]) {
+          sortedWrites.push_back(std::pair<int,DivDelayedWrite>(i,j));
+        }
+        delayedWrites[i].clear();
+      }
+
+      if (!sortedWrites.empty()) {
+        // sort if more than one chip
+        if (song.systemLen>1) {
+          std::sort(sortedWrites.begin(),sortedWrites.end(),[](const std::pair<int,DivDelayedWrite>& a, const std::pair<int,DivDelayedWrite>& b) -> bool {
+            return a.second.time<b.second.time;
+          });
+        }
+
+        // write it out
+        int lastOne=0;
+        for (std::pair<int,DivDelayedWrite>& i: sortedWrites) {
+          if (i.second.time>lastOne) {
+            // write delay
+            int delay=i.second.time-lastOne;
+            if (delay>16) {
+              w->writeC(0x61);
+              w->writeS(totalWait);
+            } else if (delay>0) {
+              w->writeC(0x70+delay-1);
+            }
+            lastOne=i.second.time;
+          }
+          // write write
+          performVGMWrite(w,song.system[i.first],i.second.write,streamIDs[i.first],loopTimer,loopFreq,loopSample,sampleDir,isSecond[i.first],directStream);
+        }
+        sortedWrites.clear();
+        totalWait-=lastOne;
       }
     } else {
       for (int i=0; i<streamID; i++) {
diff --git a/src/main.cpp b/src/main.cpp
index 83bb31b6..e0a63dd7 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -66,6 +66,7 @@ bool consoleMode=true;
 
 bool displayEngineFailError=false;
 bool cmdOutBinary=false;
+bool vgmOutDirect=false;
 
 std::vector<TAParam> params;
 
@@ -122,6 +123,11 @@ TAParamResult pBinary(String val) {
   return TA_PARAM_SUCCESS;
 }
 
+TAParamResult pDirect(String val) {
+  vgmOutDirect=true;
+  return TA_PARAM_SUCCESS;
+}
+
 TAParamResult pLogLevel(String val) {
   if (val=="trace") {
     logLevel=LOGLEVEL_TRACE;
@@ -289,6 +295,7 @@ void initParams() {
   params.push_back(TAParam("a","audio",true,pAudio,"jack|sdl","set audio engine (SDL by default)"));
   params.push_back(TAParam("o","output",true,pOutput,"<filename>","output audio to file"));
   params.push_back(TAParam("O","vgmout",true,pVGMOut,"<filename>","output .vgm data"));
+  params.push_back(TAParam("D","direct",false,pDirect,"","set VGM export direct stream mode"));
   params.push_back(TAParam("Z","zsmout",true,pZSMOut,"<filename>","output .zsm data for Commander X16 Zsound"));
   params.push_back(TAParam("C","cmdout",true,pCmdOut,"<filename>","output command stream"));
   params.push_back(TAParam("b","binary",false,pBinary,"","set command stream output format to binary"));
@@ -490,7 +497,7 @@ int main(int argc, char** argv) {
       }
     }
     if (vgmOutName!="") {
-      SafeWriter* w=e.saveVGM();
+      SafeWriter* w=e.saveVGM(NULL,true,0x171,false,vgmOutDirect);
       if (w!=NULL) {
         FILE* f=fopen(vgmOutName.c_str(),"wb");
         if (f!=NULL) {