From a2c9ec78d3cb772a856615b97a2f1c344b8ff820 Mon Sep 17 00:00:00 2001
From: DevEd <deved8@gmail.com>
Date: Sun, 10 Sep 2023 17:41:16 -0400
Subject: [PATCH] add compatibility flag for arp phase reset on new note

---
 src/engine/playback.cpp | 4 +++-
 src/engine/song.h       | 4 +++-
 src/gui/compatFlags.cpp | 4 ++++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/engine/playback.cpp b/src/engine/playback.cpp
index 572add9cf..bca403af2 100644
--- a/src/engine/playback.cpp
+++ b/src/engine/playback.cpp
@@ -1067,7 +1067,9 @@ void DivEngine::processRow(int i, bool afterDelay) {
         }
       } else if (!chan[i].noteOnInhibit) {
         dispatchCmd(DivCommand(DIV_CMD_NOTE_ON,i,chan[i].note,chan[i].volume>>8));
-        chan[i].arpStage=-1;
+        if (song.resetArpPhaseOnNewNote) {
+           chan[i].arpStage=-1;
+        }
         chan[i].goneThroughNote=true;
         chan[i].wentThroughNote=true;
         keyHit[i]=true;
diff --git a/src/engine/song.h b/src/engine/song.h
index 78c49b4e1..ae144d714 100644
--- a/src/engine/song.h
+++ b/src/engine/song.h
@@ -377,6 +377,7 @@ struct DivSong {
   bool brokenPortaLegato;
   bool brokenFMOff;
   bool preNoteNoEffect;
+  bool resetArpPhaseOnNewNote;
 
   std::vector<DivInstrument*> ins;
   std::vector<DivWavetable*> wave;
@@ -496,7 +497,8 @@ struct DivSong {
     patchbayAuto(true),
     brokenPortaLegato(false),
     brokenFMOff(false),
-    preNoteNoEffect(false) {
+    preNoteNoEffect(false),
+    resetArpPhaseOnNewNote(false) {
     for (int i=0; i<DIV_MAX_CHIPS; i++) {
       system[i]=DIV_SYSTEM_NULL;
       systemVol[i]=1.0;
diff --git a/src/gui/compatFlags.cpp b/src/gui/compatFlags.cpp
index 50fb3b0cd..d4ef64856 100644
--- a/src/gui/compatFlags.cpp
+++ b/src/gui/compatFlags.cpp
@@ -328,6 +328,10 @@ void FurnaceGUI::drawCompatFlags() {
         if (ImGui::IsItemHovered()) {
           ImGui::SetTooltip("when enabled, the pitch macro of an instrument is in frequency/period space.");
         }
+        ImGui::Checkbox("Reset arpeggio phase on new note",&e->song.resetArpPhaseOnNewNote);
+        if (ImGui::IsItemHovered()) {
+          ImGui::SetTooltip("when enabled, the arpeggio phase is reset on a new note."); // TODO: Better description
+        }
         ImGui::EndTabItem();
       }
       ImGui::EndTabBar();