From ccfb3d3407176dde5ce5bc1c5f7a1d0aadecb8ba Mon Sep 17 00:00:00 2001
From: host12prog <hungnguyen.481335@gmail.com>
Date: Thu, 10 Jul 2025 18:06:05 +0700
Subject: [PATCH] support ymfm (NO LLE SUPPORT, WHO NEEDS EMULATION THAT
 ACCURATE)

---
 src/engine/dispatchContainer.cpp |  1 +
 src/engine/platform/ym2203.cpp   | 23 ++++++++++++++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/src/engine/dispatchContainer.cpp b/src/engine/dispatchContainer.cpp
index addbaede8..ceca9598a 100644
--- a/src/engine/dispatchContainer.cpp
+++ b/src/engine/dispatchContainer.cpp
@@ -458,6 +458,7 @@ void DivDispatchContainer::init(DivSystem sys, DivEngine* eng, int chanCount, do
         ((DivPlatformYM2203Ext*)dispatch)->setCombo(eng->getConfInt("opn1Core", 1));
       }
       ((DivPlatformYM2203Ext*)dispatch)->setCSM(1);
+      ((DivPlatformYM2203Ext*)dispatch)->setExtSSG(1);
       break;
     case DIV_SYSTEM_YM2608:
       dispatch=new DivPlatformYM2608;
diff --git a/src/engine/platform/ym2203.cpp b/src/engine/platform/ym2203.cpp
index 2d74ab4fc..0265634db 100644
--- a/src/engine/platform/ym2203.cpp
+++ b/src/engine/platform/ym2203.cpp
@@ -268,6 +268,7 @@ void DivPlatformYM2203::acquire_combo(short** buf, size_t len) {
 
 void DivPlatformYM2203::acquire_ymfm(short** buf, size_t len) {
   thread_local int os;
+  thread_local int os1, os2;
 
   ymfm::ym2203::fm_engine* fme=fm->debug_fm_engine();
 
@@ -310,12 +311,27 @@ void DivPlatformYM2203::acquire_ymfm(short** buf, size_t len) {
     fm->generate(&fmout);
     iface.clock(24);
 
-    os=((fmout.data[0]*fmVol)>>8)+(((fmout.data[1]+fmout.data[2]+fmout.data[3])*ssgVol)>>8);
+    os=((fmout.data[0]*fmVol)>>8);
     if (os<-32768) os=-32768;
     if (os>32767) os=32767;
-  
-    buf[0][h]=os;
 
+    if (stereo) {
+      // so ugly
+      os1=((fmout.data[1]+((fmout.data[2]*centerVol+fmout.data[3]*sideVol)>>8))*ssgVol)>>8;
+      os2=((((fmout.data[1]*sideVol+fmout.data[2]*centerVol)>>8)+fmout.data[3])*ssgVol)>>8;
+      if (os1<-32768) os1=-32768;
+      if (os1>32767) os1=32767;
+      if (os2<-32768) os2=-32768;
+      if (os2>32767) os2=32767;
+      buf[0][h]=os+os1;
+      buf[1][h]=os+os2;
+    } else {
+      os+=((fmout.data[1]+fmout.data[2]+fmout.data[3])*ssgVol)>>8;
+      if (os<-32768) os=-32768;
+      if (os>32767) os=32767;
+      buf[0][h]=os;
+      if (extendedSSG) buf[1][h]=os;
+    }
     
     for (int i=0; i<3; i++) {
       int out=(fmChan[i]->debug_output(0)+fmChan[i]->debug_output(1))<<1;
@@ -493,6 +509,7 @@ void DivPlatformYM2203::acquire_lle(short** buf, size_t len) {
     if (outL>32767) outL=32767;
 
     buf[0][h]=outL;
+    if (extendedSSG) buf[1][h]=outL;
   }
 
   for (int i=0; i<7; i++) {