From d3718ccaf0e42d2f0d3db5ce5e17f85c567b34e4 Mon Sep 17 00:00:00 2001
From: tildearrow <tildearrow@protonmail.com>
Date: Sat, 8 Oct 2022 02:03:09 -0500
Subject: [PATCH] YMU759: fix 4-op ins loading in .dmf

---
 src/engine/fileOps.cpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/engine/fileOps.cpp b/src/engine/fileOps.cpp
index 41ec55e62..a13182e32 100644
--- a/src/engine/fileOps.cpp
+++ b/src/engine/fileOps.cpp
@@ -494,6 +494,19 @@ bool DivEngine::loadDMF(unsigned char* file, size_t len) {
                ins->fm.op[j].ssgEnv
                );
         }
+
+        // swap alg operator 2 and 3 if YMU759
+        if (ds.system[0]==DIV_SYSTEM_YMU759 && ins->fm.ops==4) {
+          DivInstrumentFM::Operator oldOp=ins->fm.op[2];
+          ins->fm.op[2]=ins->fm.op[1];
+          ins->fm.op[1]=oldOp;
+
+          if (ins->fm.alg==1) {
+            ins->fm.alg=2;
+          } else if (ins->fm.alg==2) {
+            ins->fm.alg=1;
+          }
+        }
       } else { // STD
         if (ds.system[0]!=DIV_SYSTEM_GB || ds.version<0x12) {
           ins->std.volMacro.len=reader.readC();