From 6d33fadbc57f0285189e6f094d7d4cf5f665ca59 Mon Sep 17 00:00:00 2001
From: tildearrow <me@tildearrow.org>
Date: Thu, 9 Mar 2023 20:00:15 -0500
Subject: [PATCH] finish this later

---
 src/engine/platform/amiga.cpp | 49 ++++++++++++++++++++++++++++++++++-
 src/engine/platform/amiga.h   | 31 +++++++++++++++++++++-
 2 files changed, 78 insertions(+), 2 deletions(-)

diff --git a/src/engine/platform/amiga.cpp b/src/engine/platform/amiga.cpp
index b86beb19..bb0eb1c6 100644
--- a/src/engine/platform/amiga.cpp
+++ b/src/engine/platform/amiga.cpp
@@ -84,6 +84,52 @@ void DivPlatformAmiga::acquire(short** buf, size_t len) {
     outR=0;
 
     // NEW CODE
+    for (int i=0; i<4; i++) {
+      amiga.volPos=(amiga.volPos+1)&AMIGA_VPMASK;
+
+      // run DMA
+      if (amiga.audEn[i]) {
+        amiga.audTick[i]-=AMIGA_DIVIDER;
+        if (amiga.audTick[i]<0) {
+          if (amiga.audByte[i]) {
+            // read next samples
+            amiga.audDat[0][i]=sampleMem[((amiga.dmaLoc[i]+amiga.dmaPos[i])<<1)&chipMask];
+            amiga.audDat[1][i]=sampleMem[(1+((amiga.dmaLoc[i]+amiga.dmaPos[i])<<1))&chipMask];
+
+            // check for length
+            if (amiga.dmaPos[i]>amiga.dmaLen[i]) {
+              if (amiga.audInt[i]) irq(i);
+              amiga.dmaLoc[i]=amiga.audLoc[i];
+              amiga.dmaPos[i]=0;
+              amiga.dmaLen[i]=amiga.audLen[i];
+            }
+          }
+
+          amiga.audByte[i]=!amiga.audByte[i];
+        }
+      }
+
+      // output
+      if (!isMuted[i]) {
+        if (amiga.audVol[i]>=64) {
+          output=amiga.audDat[amiga.audByte[i]][i]<<6;
+        } else if (amiga.audVol[i]<=0) {
+          output=0;
+        } else {
+          output=amiga.audDat[amiga.audByte[i]][i]*volTable[amiga.audVol[i]][amiga.volPos];
+        }
+        if (i==0 || i==3) {
+          outL+=(output*sep1)>>7;
+          outR+=(output*sep2)>>7;
+        } else {
+          outL+=(output*sep2)>>7;
+          outR+=(output*sep1)>>7;
+        }
+        oscBuf[i]->data[oscBuf[i]->needle++]=output<<2;
+      } else {
+        oscBuf[i]->data[oscBuf[i]->needle++]=0;
+      }
+    }
 
     // OLD CODE
     for (int i=0; i<4; i++) {
@@ -498,7 +544,8 @@ void DivPlatformAmiga::renderSamples(int sysID) {
   memset(sampleOff,0,256*sizeof(unsigned int));
   memset(sampleLoaded,0,256*sizeof(bool));
 
-  size_t memPos=0;
+  // first 1024 bytes reserved for wavetable
+  size_t memPos=1024;
   for (int i=0; i<parent->song.sampleLen; i++) {
     DivSample* s=parent->song.sample[i];
     if (!s->renderOn[0][sysID]) {
diff --git a/src/engine/platform/amiga.h b/src/engine/platform/amiga.h
index f1da65d3..b2311405 100644
--- a/src/engine/platform/amiga.h
+++ b/src/engine/platform/amiga.h
@@ -67,10 +67,37 @@ class DivPlatformAmiga: public DivDispatch {
   bool amigaModel;
   bool filterOn;
 
+  struct Amiga {
+    // register state
+    bool audInt[4]; // interrupt on
+    bool audEn[4]; // audio DMA on
+    bool useP[4]; // period modulation
+    bool useV[4]; // volume modulatiom
+
+    unsigned int audLoc[4]; // address
+    unsigned short audLen[4]; // length
+    unsigned short audPer[4]; // period
+    unsigned char audVol[4]; // volume
+    signed char audDat[2][4]; // data
+    
+
+    // internal state
+    int audTick[4]; // tick of period
+    unsigned int dmaLoc[4]; // address
+    unsigned short dmaPos[4]; // position
+
+    bool audByte[4]; // which byte of audDat to output
+    unsigned char volPos; // position of volume PWM
+
+    Amiga() {
+      memset(this,0,sizeof(*this));
+    }
+  } amiga;
+
   int filter[2][4];
   int filtConst;
   int filtConstOff, filtConstOn;
-  int chipMem;
+  int chipMem, chipMask;
 
   unsigned char volTable[64][64];
 
@@ -85,6 +112,8 @@ class DivPlatformAmiga: public DivDispatch {
   friend void putDispatchChip(void*,int);
   friend void putDispatchChan(void*,int,int);
 
+  void irq(int ch);
+
   public:
     void acquire(short** buf, size_t len);
     int dispatch(DivCommand c);