From 319c559f4771602ae4c8bf3af11ee7c9e62ea103 Mon Sep 17 00:00:00 2001
From: tildearrow <tildearrow@protonmail.com>
Date: Wed, 23 Feb 2022 03:19:32 -0500
Subject: [PATCH] compound system flattening, part 2

.dmf saving implemented. only available for the following setups:
- YM2612 + SMS = Genesis
- YM2612 ext3 + SMS = Genesis ext3
- YM2151 + SegaPCM compat = Arcade
- SMS + OPLL = SMS with FM expansion
---
 src/engine/fileOps.cpp | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/src/engine/fileOps.cpp b/src/engine/fileOps.cpp
index 6eaeccecc..743d55866 100644
--- a/src/engine/fileOps.cpp
+++ b/src/engine/fileOps.cpp
@@ -1447,15 +1447,28 @@ SafeWriter* DivEngine::saveDMF(unsigned char version) {
     lastError="invalid version to save in! this is a bug!";
     return NULL;
   }
+  // check whether system is compound
+  bool isFlat=false;
+  if (song.systemLen==2) {
+    if (song.system[0]==DIV_SYSTEM_YM2612 && song.system[1]==DIV_SYSTEM_SMS) {
+      isFlat=true;  
+    }
+    if (song.system[0]==DIV_SYSTEM_YM2612_EXT && song.system[1]==DIV_SYSTEM_SMS) {
+      isFlat=true;  
+    }
+    if (song.system[0]==DIV_SYSTEM_YM2151 && song.system[1]==DIV_SYSTEM_SEGAPCM_COMPAT) {
+      isFlat=true;
+    }
+    if (song.system[0]==DIV_SYSTEM_SMS && song.system[1]==DIV_SYSTEM_OPLL) {
+      isFlat=true;  
+    }
+  }
   // fail if more than one system
-  // TODO: fix this mess for the flattening in 0.6
-  if (!(song.system[0]==DIV_SYSTEM_SMS && song.system[1]==DIV_SYSTEM_OPLL)) {
-    if (song.systemLen!=1) {
+  if (!isFlat && song.systemLen!=1) {
       logE("cannot save multiple systems in this format!\n");
       lastError="multiple systems not possible on .dmf";
       return NULL;
     }
-  }
   // fail if this is an YMU759 song
   if (song.system[0]==DIV_SYSTEM_YMU759) {
     logE("cannot save YMU759 song!\n");
@@ -1469,7 +1482,7 @@ SafeWriter* DivEngine::saveDMF(unsigned char version) {
     return NULL;
   }
   // fail if the system is Furnace-exclusive
-  if (systemToFile(song.system[0])&0x80) {
+  if (!isFlat && systemToFile(song.system[0])&0x80) {
     logE("cannot save Furnace-exclusive system song!\n");
     lastError="this system is not possible on .dmf";
     return NULL;
@@ -1485,7 +1498,16 @@ SafeWriter* DivEngine::saveDMF(unsigned char version) {
   // version
   w->writeC(version);
   DivSystem sys=DIV_SYSTEM_NULL;
-  if (song.system[0]==DIV_SYSTEM_SMS && song.system[1]==DIV_SYSTEM_OPLL) {
+  if (song.system[0]==DIV_SYSTEM_YM2612 && song.system[1]==DIV_SYSTEM_SMS) {
+    w->writeC(systemToFile(DIV_SYSTEM_GENESIS));
+    sys=DIV_SYSTEM_GENESIS;
+  } else if (song.system[0]==DIV_SYSTEM_YM2612_EXT && song.system[1]==DIV_SYSTEM_SMS) {
+    w->writeC(systemToFile(DIV_SYSTEM_GENESIS_EXT));
+    sys=DIV_SYSTEM_GENESIS_EXT;
+  } else if (song.system[0]==DIV_SYSTEM_YM2151 && song.system[1]==DIV_SYSTEM_SEGAPCM_COMPAT) {
+    w->writeC(systemToFile(DIV_SYSTEM_ARCADE));
+    sys=DIV_SYSTEM_ARCADE;
+  } else if (song.system[0]==DIV_SYSTEM_SMS && song.system[1]==DIV_SYSTEM_OPLL) {
     w->writeC(systemToFile(DIV_SYSTEM_SMS_OPLL));
     sys=DIV_SYSTEM_SMS_OPLL;
   } else {