From 32cdd81919ba0aee534210791907ba999c79e9bf Mon Sep 17 00:00:00 2001
From: tildearrow <tildearrow@protonmail.com>
Date: Thu, 22 Sep 2022 00:01:23 -0500
Subject: [PATCH] OPL: fix chan osc in 4-op mode

---
 src/engine/platform/opl.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/engine/platform/opl.cpp b/src/engine/platform/opl.cpp
index 2dd6d1dcf..e1ad92f5f 100644
--- a/src/engine/platform/opl.cpp
+++ b/src/engine/platform/opl.cpp
@@ -1421,6 +1421,15 @@ DivMacroInt* DivPlatformOPL::getChanMacroInt(int ch) {
 
 DivDispatchOscBuffer* DivPlatformOPL::getOscBuffer(int ch) {
   if (ch>=18) return NULL;
+  if (oplType==3 && ch<12) {
+    if (chan[ch&(~1)].fourOp) {
+      if (ch&1) {
+        return oscBuf[ch-1];
+      } else {
+        return oscBuf[ch+1];
+      }
+    }
+  }
   return oscBuf[ch];
 }