From 6b040084e08f0fca3201a01616b1302aa7b943bd Mon Sep 17 00:00:00 2001
From: tildearrow <tildearrow@protonmail.com>
Date: Fri, 4 Feb 2022 21:35:24 -0500
Subject: [PATCH] Genesis: add alternate clock speed

---
 src/engine/platform/genesis.cpp | 4 +++-
 src/engine/song.h               | 1 +
 src/gui/gui.cpp                 | 3 +++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/engine/platform/genesis.cpp b/src/engine/platform/genesis.cpp
index 4f487bb7f..9027a8777 100644
--- a/src/engine/platform/genesis.cpp
+++ b/src/engine/platform/genesis.cpp
@@ -794,7 +794,9 @@ void DivPlatformGenesis::setYMFM(bool use) {
 }
 
 void DivPlatformGenesis::setFlags(unsigned int flags) {
-  if (flags==2) {
+  if (flags==3) {
+    chipClock=COLOR_NTSC*12.0/7.0;
+  } else if (flags==2) {
     chipClock=8000000.0;
   } else if (flags==1) {
     chipClock=COLOR_PAL*12.0/7.0;
diff --git a/src/engine/song.h b/src/engine/song.h
index a04060182..4709566a5 100644
--- a/src/engine/song.h
+++ b/src/engine/song.h
@@ -146,6 +146,7 @@ struct DivSong {
   //     - 0: Genesis NTSC (7.67MHz)
   //     - 1: Genesis PAL (7.61MHz)
   //     - 2: 8MHz
+  //     - 3: AtGames Genesis (???)
   // - YM2151:
   //   - bit 0-1: clock rate
   //     - 0: 3.58MHz (NTSC)
diff --git a/src/gui/gui.cpp b/src/gui/gui.cpp
index ee2d4f958..559f9a9ab 100644
--- a/src/gui/gui.cpp
+++ b/src/gui/gui.cpp
@@ -5176,6 +5176,9 @@ bool FurnaceGUI::loop() {
                 if (ImGui::RadioButton("FM Towns (8MHz)",(flags&3)==2)) {
                   e->setSysFlags(i,(flags&0x80000000)|2);
                 }
+                if (ImGui::RadioButton("AtGames Genesis",(flags&3)==3)) {
+                  e->setSysFlags(i,(flags&0x80000000)|3);
+                }
                 bool ladder=flags&0x80000000;
                 if (ImGui::Checkbox("Enable DAC distortion",&ladder)) {
                   e->setSysFlags(i,(flags&(~0x80000000))|(ladder?0x80000000:0));