From 5eae36f0923c95b920dd64a5c483ed9419d370f6 Mon Sep 17 00:00:00 2001
From: tildearrow <me@tildearrow.org>
Date: Thu, 17 Oct 2024 15:51:04 -0500
Subject: [PATCH] Lynx: direct stream mode

---
 src/engine/platform/lynx.cpp | 73 ++++++++++++++++++++++++------------
 src/engine/platform/lynx.h   | 10 +++++
 2 files changed, 60 insertions(+), 23 deletions(-)

diff --git a/src/engine/platform/lynx.cpp b/src/engine/platform/lynx.cpp
index 737392e80..03370babb 100644
--- a/src/engine/platform/lynx.cpp
+++ b/src/engine/platform/lynx.cpp
@@ -22,7 +22,7 @@
 #include "../bsr.h"
 #include <math.h>
 
-#define rWrite(a,v) {if (!skipRegisterWrites) {mikey->write(a,v); if (dumpWrites) {addWrite(a,v);}}}
+#define rWrite(a,v) {if (!skipRegisterWrites) {writes.push(QueuedWrite(a,v)); if (dumpWrites) {addWrite(a,v);}}}
 
 #define WRITE_VOLUME(ch,v) rWrite(0x20+(ch<<3),(v))
 #define WRITE_FEEDBACK(ch,v) rWrite(0x21+(ch<<3),(v))
@@ -123,40 +123,64 @@ const char** DivPlatformLynx::getRegisterSheet() {
   return regCheatSheetLynx;
 }
 
-void DivPlatformLynx::acquire(short** buf, size_t len) {
-  for (size_t h=0; h<len; h++) {
-    for (int i=0; i<4; i++) {
-      if (chan[i].pcm && chan[i].sample>=0 && chan[i].sample<parent->song.sampleLen) {
-        chan[i].sampleAccum-=chan[i].sampleFreq;
-        if (chan[i].sampleAccum<0) {
-          chan[i].sampleAccum+=rate;
-          DivSample* s=parent->getSample(chan[i].sample);
-          if (s!=NULL) {
-            if (isMuted[i]) {
+void DivPlatformLynx::processDAC(int sRate) {
+  for (int i=0; i<4; i++) {
+    if (chan[i].pcm && chan[i].sample>=0 && chan[i].sample<parent->song.sampleLen) {
+      chan[i].sampleAccum-=chan[i].sampleFreq;
+      while (chan[i].sampleAccum<0) {
+        chan[i].sampleAccum+=sRate;
+        DivSample* s=parent->getSample(chan[i].sample);
+        if (s!=NULL) {
+          if (isMuted[i]) {
+            WRITE_OUTPUT(i,0);
+          } else {
+            if (chan[i].samplePos<0 || chan[i].samplePos>=(int)s->samples) {
               WRITE_OUTPUT(i,0);
             } else {
-              if (chan[i].samplePos<0 || chan[i].samplePos>=(int)s->samples) {
-                WRITE_OUTPUT(i,0);
-              } else {
-                WRITE_OUTPUT(i,CLAMP((s->data8[chan[i].samplePos]*chan[i].outVol)>>7,-128,127));
-              }
+              WRITE_OUTPUT(i,CLAMP((s->data8[chan[i].samplePos]*chan[i].outVol)>>7,-128,127));
             }
-            chan[i].samplePos++;
+          }
+          chan[i].samplePos++;
 
-            if (s->isLoopable() && chan[i].samplePos>=s->loopEnd) {
-              chan[i].samplePos=s->loopStart;
-            } else if (chan[i].samplePos>=(int)s->samples) {
-              chan[i].sample=-1;
-            }
+          if (s->isLoopable() && chan[i].samplePos>=s->loopEnd) {
+            chan[i].samplePos=s->loopStart;
+          } else if (chan[i].samplePos>=(int)s->samples) {
+            chan[i].sample=-1;
           }
         }
       }
     }
+  }
+}
+
+void DivPlatformLynx::acquire(short** buf, size_t len) {
+  for (size_t h=0; h<len; h++) {
+    processDAC(rate);
+
+    while (!writes.empty()) {
+      QueuedWrite& w=writes.front();
+      mikey->write(w.addr,w.val);
+      writes.pop_front();
+    }
 
     mikey->sampleAudio(buf[0]+h,buf[1]+h,1,oscBuf);
   }
 }
 
+void DivPlatformLynx::fillStream(std::vector<DivDelayedWrite>& stream, int sRate, size_t len) {
+  writes.clear();
+  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 DivPlatformLynx::tick(bool sysTick) {
   for (int i=0; i<4; i++) {
     chan[i].std.next();
@@ -308,7 +332,9 @@ int DivPlatformLynx::dispatch(DivCommand c) {
         } else {
           chan[c.chan].samplePos=0;
         }
-        if (dumpWrites) addWrite(0xffff0000+(c.chan<<8),chan[c.chan].sample);
+        if (dumpWrites) {
+          addWrite(0xffff0000+(c.chan<<8),chan[c.chan].sample);
+        }
       }
       if (c.value!=DIV_NOTE_NULL) {
         chan[c.chan].baseFreq=NOTE_PERIODIC(c.value);
@@ -499,6 +525,7 @@ void DivPlatformLynx::reset() {
     chan[i]=DivPlatformLynx::Channel();
     chan[i].std.setEngine(parent);
   }
+  writes.clear();
   if (dumpWrites) {
     addWrite(0xffffffff,0);
   }
diff --git a/src/engine/platform/lynx.h b/src/engine/platform/lynx.h
index e7dbfc8be..ffc91e9d7 100644
--- a/src/engine/platform/lynx.h
+++ b/src/engine/platform/lynx.h
@@ -68,10 +68,20 @@ class DivPlatformLynx: public DivDispatch {
   bool isMuted[4];
   bool tuned;
   std::unique_ptr<Lynx::Mikey> mikey;  
+  struct QueuedWrite {
+    unsigned char addr;
+    unsigned char val;
+    QueuedWrite(): addr(0), val(9) {}
+    QueuedWrite(unsigned char a, unsigned char v): addr(a), val(v) {}
+  };
+  FixedQueue<QueuedWrite,512> writes;
   friend void putDispatchChip(void*,int);
   friend void putDispatchChan(void*,int,int);
+
+  void processDAC(int sRate);
   public:
     void acquire(short** buf, 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);