From 317aca056465ef026a69a301bd75017068255ad9 Mon Sep 17 00:00:00 2001
From: tildearrow <me@tildearrow.org>
Date: Thu, 22 Jun 2023 15:20:48 -0500
Subject: [PATCH] VGM export: NES DPCM, part 1

still does not work
---
 src/engine/engine.h   |  2 +-
 src/engine/vgmOps.cpp | 38 +++++++++++++++++++++++++++++++++-----
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/src/engine/engine.h b/src/engine/engine.h
index bae7daa9..85e8f641 100644
--- a/src/engine/engine.h
+++ b/src/engine/engine.h
@@ -489,7 +489,7 @@ class DivEngine {
   void processRow(int i, bool afterDelay);
   void nextOrder();
   void nextRow();
-  void performVGMWrite(SafeWriter* w, DivSystem sys, DivRegWrite& write, int streamOff, double* loopTimer, double* loopFreq, int* loopSample, bool* sampleDir, bool isSecond, int* pendingFreq, int* playingSample, bool directStream);
+  void performVGMWrite(SafeWriter* w, DivSystem sys, DivRegWrite& write, int streamOff, double* loopTimer, double* loopFreq, int* loopSample, bool* sampleDir, bool isSecond, int* pendingFreq, int* playingSample, size_t bankOffset, bool directStream);
   // returns true if end of song.
   bool nextTick(bool noAccum=false, bool inhibitLowLat=false);
   bool perSystemEffect(int ch, unsigned char effect, unsigned char effectVal);
diff --git a/src/engine/vgmOps.cpp b/src/engine/vgmOps.cpp
index 7a6caa67..5cf18e42 100644
--- a/src/engine/vgmOps.cpp
+++ b/src/engine/vgmOps.cpp
@@ -24,7 +24,7 @@
 
 constexpr int MASTER_CLOCK_PREC=(sizeof(void*)==8)?8:0;
 
-void DivEngine::performVGMWrite(SafeWriter* w, DivSystem sys, DivRegWrite& write, int streamOff, double* loopTimer, double* loopFreq, int* loopSample, bool* sampleDir, bool isSecond, int* pendingFreq, int* playingSample, bool directStream) {
+void DivEngine::performVGMWrite(SafeWriter* w, DivSystem sys, DivRegWrite& write, int streamOff, double* loopTimer, double* loopFreq, int* loopSample, bool* sampleDir, bool isSecond, int* pendingFreq, int* playingSample, size_t bankOffset, bool directStream) {
   unsigned char baseAddr1=isSecond?0xa0:0x50;
   unsigned char baseAddr2=isSecond?0x80:0;
   unsigned short baseAddr2S=isSecond?0x8000:0;
@@ -577,6 +577,28 @@ void DivEngine::performVGMWrite(SafeWriter* w, DivSystem sys, DivRegWrite& write
         break;
     }
   }
+  if (write.addr==0xffff0004) { // switch sample bank
+    switch (sys) {
+      case DIV_SYSTEM_NES: {
+        unsigned int bankAddr=bankOffset+(write.val<<14);
+        w->writeC(0x68);
+        w->writeC(0x6c);
+        w->writeC(0x07);
+        w->writeC(bankAddr&0xff);
+        w->writeC((bankAddr>>8)&0xff);
+        w->writeC((bankAddr>>16)&0xff);
+        w->writeC(0x00);
+        w->writeC(0xc0);
+        w->writeC(0x00);
+        w->writeC(0x00);
+        w->writeC(0x40);
+        w->writeC(0x00);
+        break;
+      }
+      default:
+        break;
+    }
+  }
   if (write.addr>=0xffff0000) { // Furnace special command
     if (!directStream) {
       unsigned char streamID=streamOff+((write.addr&0xff00)>>8);
@@ -1054,7 +1076,7 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
   bool willExport[DIV_MAX_CHIPS];
   bool isSecond[DIV_MAX_CHIPS];
   int streamIDs[DIV_MAX_CHIPS];
-  
+  size_t bankOffset[DIV_MAX_CHIPS];
   double loopTimer[DIV_MAX_CHANS];
   double loopFreq[DIV_MAX_CHANS];
   int loopSample[DIV_MAX_CHANS];
@@ -1072,6 +1094,8 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
   bool mayWriteRate=(fmod(curSubSong->hz,1.0)<0.00001 || fmod(curSubSong->hz,1.0)>0.99999);
   int countDown=MAX(0,trailingTicks)+1;
 
+  memset(bankOffset,0,DIV_MAX_CHIPS*sizeof(size_t));
+
   for (int i=0; i<DIV_MAX_CHANS; i++) {
     loopTimer[i]=0;
     loopFreq[i]=0;
@@ -1096,6 +1120,8 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
   DivDispatch* writeMSM6295[2]={NULL,NULL};
   DivDispatch* writeGA20[2]={NULL,NULL};
   DivDispatch* writeNES[2]={NULL,NULL};
+  
+  int writeNESIndex[2]={0,0};
 
   size_t bankOffsetNESCurrent=0;
   size_t bankOffsetNES[2]={0,0};
@@ -1170,12 +1196,14 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
           willExport[i]=true;
           writeNESSamples=true;
           writeNES[0]=disCont[i].dispatch;
+          writeNESIndex[0]=i;
         } else if (!(hasNES&0x40000000)) {
           isSecond[i]=true;
           CHIP_VOL_SECOND(20,1.7);
           willExport[i]=true;
           hasNES|=0x40000000;
           writeNES[1]=disCont[i].dispatch;
+          writeNESIndex[1]=i;
           howManyChips++;
         }
         break;
@@ -1976,7 +2004,6 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
       w->writeI(0);
       w->write(writeGA20[i]->getSampleMem(),writeGA20[i]->getSampleMemUsage());
     }
-    // TODO
     if (writeNES[i]!=NULL && writeNES[i]->getSampleMemUsage()>0) {
       size_t howMuchWillBeWritten=writeNES[i]->getSampleMemUsage();
       w->writeC(0x67);
@@ -1985,6 +2012,7 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
       w->writeI(howMuchWillBeWritten);
       w->write(writeNES[i]->getSampleMem(),howMuchWillBeWritten);
       bankOffsetNES[i]=bankOffsetNESCurrent;
+      bankOffset[writeNESIndex[i]]=bankOffsetNES[i];
       bankOffsetNESCurrent+=howMuchWillBeWritten;
     }
   }
@@ -2196,7 +2224,7 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
     for (int i=0; i<song.systemLen; i++) {
       std::vector<DivRegWrite>& writes=disCont[i].dispatch->getRegisterWrites();
       for (DivRegWrite& j: writes) {
-        performVGMWrite(w,song.system[i],j,streamIDs[i],loopTimer,loopFreq,loopSample,sampleDir,isSecond[i],pendingFreq,playingSample,directStream);
+        performVGMWrite(w,song.system[i],j,streamIDs[i],loopTimer,loopFreq,loopSample,sampleDir,isSecond[i],pendingFreq,playingSample,bankOffset[i],directStream);
         writeCount++;
       }
       writes.clear();
@@ -2236,7 +2264,7 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
             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],pendingFreq,playingSample,directStream);
+          performVGMWrite(w,song.system[i.first],i.second.write,streamIDs[i.first],loopTimer,loopFreq,loopSample,sampleDir,isSecond[i.first],pendingFreq,playingSample,bankOffset[i.first],directStream);
           // handle global Furnace commands
 
           writeCount++;