From 340052cf0a50f6a848d5c545df4ada5a6c077283 Mon Sep 17 00:00:00 2001
From: tildearrow <tildearrow@protonmail.com>
Date: Thu, 11 Aug 2022 00:46:15 -0500
Subject: [PATCH] Game Boy: add chip revision flag

---
 src/engine/platform/gb.cpp | 35 ++++++++++++++++++++++++++++++-----
 src/engine/platform/gb.h   |  9 +++++++++
 src/gui/sysConf.cpp        | 13 +++++++++++++
 3 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/src/engine/platform/gb.cpp b/src/engine/platform/gb.cpp
index 31ce2424..39ccaf56 100644
--- a/src/engine/platform/gb.cpp
+++ b/src/engine/platform/gb.cpp
@@ -21,8 +21,8 @@
 #include "../engine.h"
 #include <math.h>
 
-#define rWrite(a,v) if (!skipRegisterWrites) {GB_apu_write(gb,a,v); regPool[(a)&0x7f]=v; if (dumpWrites) {addWrite(a,v);} }
-#define immWrite(a,v) {GB_apu_write(gb,a,v); regPool[(a)&0x7f]=v; if (dumpWrites) {addWrite(a,v);} }
+#define rWrite(a,v) if (!skipRegisterWrites) {writes.emplace(a,v); regPool[(a)&0x7f]=v; if (dumpWrites) {addWrite(a,v);} }
+#define immWrite(a,v) {writes.emplace(a,v); regPool[(a)&0x7f]=v; if (dumpWrites) {addWrite(a,v);} }
 
 #define CHIP_DIVIDER 16
 
@@ -84,6 +84,12 @@ const char* DivPlatformGB::getEffectName(unsigned char effect) {
 
 void DivPlatformGB::acquire(short* bufL, short* bufR, size_t start, size_t len) {
   for (size_t i=start; i<start+len; i++) {
+    if (!writes.empty()) {
+      QueuedWrite& w=writes.front();
+      GB_apu_write(gb,w.addr,w.val);
+      writes.pop();
+    }
+
     GB_advance_cycles(gb,16);
     bufL[i]=gb->apu_output.final_sample.left;
     bufR[i]=gb->apu_output.final_sample.right;
@@ -97,8 +103,8 @@ void DivPlatformGB::acquire(short* bufL, short* bufR, size_t start, size_t len)
 void DivPlatformGB::updateWave() {
   rWrite(0x1a,0);
   for (int i=0; i<16; i++) {
-    int nibble1=15-ws.output[((i<<1)+antiClickWavePos)&31];
-    int nibble2=15-ws.output[((1+(i<<1))+antiClickWavePos)&31];
+    int nibble1=15-ws.output[((i<<1)+antiClickWavePos-1)&31];
+    int nibble2=15-ws.output[((1+(i<<1))+antiClickWavePos-1)&31];
     rWrite(0x30+i,(nibble1<<4)|nibble2);
   }
   antiClickWavePos&=31;
@@ -559,7 +565,7 @@ void DivPlatformGB::reset() {
   }
   memset(gb,0,sizeof(GB_gameboy_t));
   memset(regPool,0,128);
-  gb->model=GB_MODEL_DMG_B;
+  gb->model=model;
   GB_apu_init(gb);
   GB_set_sample_rate(gb,rate);
   // enable all channels
@@ -581,6 +587,10 @@ bool DivPlatformGB::isStereo() {
   return true;
 }
 
+bool DivPlatformGB::getDCOffRequired() {
+  return (model==GB_MODEL_AGB);
+}
+
 void DivPlatformGB::notifyInsChange(int ins) {
   for (int i=0; i<4; i++) {
     if (chan[i].ins==ins) {
@@ -613,6 +623,20 @@ void DivPlatformGB::poke(std::vector<DivRegWrite>& wlist) {
 
 void DivPlatformGB::setFlags(unsigned int flags) {
   antiClickEnabled=!(flags&8);
+  switch (flags&3) {
+    case 0:
+      model=GB_MODEL_DMG_B;
+      break;
+    case 1:
+      model=GB_MODEL_CGB_C;
+      break;
+    case 2:
+      model=GB_MODEL_CGB_E;
+      break;
+    case 3:
+      model=GB_MODEL_AGB;
+      break;
+  }
 }
 
 int DivPlatformGB::init(DivEngine* p, int channels, int sugRate, unsigned int flags) {
@@ -626,6 +650,7 @@ int DivPlatformGB::init(DivEngine* p, int channels, int sugRate, unsigned int fl
   parent=p;
   dumpWrites=false;
   skipRegisterWrites=false;
+  model=GB_MODEL_DMG_B;
   gb=new GB_gameboy_t;
   setFlags(flags);
   reset();
diff --git a/src/engine/platform/gb.h b/src/engine/platform/gb.h
index e4b8568b..ce582979 100644
--- a/src/engine/platform/gb.h
+++ b/src/engine/platform/gb.h
@@ -24,6 +24,7 @@
 #include "../macroInt.h"
 #include "../waveSynth.h"
 #include "sound/gb/gb.h"
+#include <queue>
 
 class DivPlatformGB: public DivDispatch {
   struct Channel {
@@ -73,10 +74,17 @@ class DivPlatformGB: public DivDispatch {
   bool antiClickEnabled;
   unsigned char lastPan;
   DivWaveSynth ws;
+  struct QueuedWrite {
+      unsigned char addr;
+      unsigned char val;
+      QueuedWrite(unsigned char a, unsigned char v): addr(a), val(v) {}
+  };
+  std::queue<QueuedWrite> writes;
 
   int antiClickPeriodCount, antiClickWavePos;
 
   GB_gameboy_t* gb;
+  GB_model_t model;
   unsigned char regPool[128];
   
   unsigned char procMute();
@@ -96,6 +104,7 @@ class DivPlatformGB: public DivDispatch {
     void muteChannel(int ch, bool mute);
     int getPortaFloor(int ch);
     bool isStereo();
+    bool getDCOffRequired();
     void notifyInsChange(int ins);
     void notifyWaveChange(int wave);
     void notifyInsDeletion(void* ins);
diff --git a/src/gui/sysConf.cpp b/src/gui/sysConf.cpp
index 3259f00c..48449034 100644
--- a/src/gui/sysConf.cpp
+++ b/src/gui/sysConf.cpp
@@ -185,6 +185,19 @@ void FurnaceGUI::drawSysConf(int chan, DivSystem type, unsigned int& flags, bool
       if (ImGui::Checkbox("Disable anti-click",&antiClick)) {
         copyOfFlags=(flags&(~8))|(antiClick<<3);
       }
+      ImGui::Text("Chip revision:");
+      if (ImGui::RadioButton("Original (DMG)",(flags&7)==0)) {
+        copyOfFlags=(flags&(~7))|0;
+      }
+      if (ImGui::RadioButton("Game Boy Color (rev C)",(flags&7)==1)) {
+        copyOfFlags=(flags&(~7))|1;
+      }
+      if (ImGui::RadioButton("Game Boy Color (rev E)",(flags&7)==2)) {
+        copyOfFlags=(flags&(~7))|2;
+      }
+      if (ImGui::RadioButton("Game Boy Advance",(flags&7)==3)) {
+        copyOfFlags=(flags&(~7))|3;
+      }
       break;
     }
     case DIV_SYSTEM_OPLL: