From ca19c631d99feffd1b4932ddf115bfd0f5133dfe Mon Sep 17 00:00:00 2001
From: tildearrow <me@tildearrow.org>
Date: Sun, 18 Jan 2026 19:04:49 -0500
Subject: [PATCH] add compatibility flag for vol slide reset on targ

et
---
 src/engine/playback.cpp | 23 ++++++++++++++++-------
 src/engine/song.cpp     |  3 +++
 src/engine/song.h       |  1 +
 src/gui/compatFlags.cpp |  6 ++++++
 4 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/src/engine/playback.cpp b/src/engine/playback.cpp
index eeb3509d0..2e1f934a8 100644
--- a/src/engine/playback.cpp
+++ b/src/engine/playback.cpp
@@ -2232,24 +2232,34 @@ bool DivEngine::nextTick(bool noAccum, bool inhibitLowLat) {
                 } else if (chan[i].volSpeed<0) {
                   chan[i].volume=MIN(preSpeedVol,chan[i].volSpeedTarget);
                 }
-                chan[i].volSpeed=0;
-                chan[i].volSpeedTarget=-1;
+                // COMPAT FLAG: don't stop volume slides after reaching target
+                // - when enabled, we don't reset the volume speed
+                if (!song.compatFlags.noVolSlideReset) {
+                  chan[i].volSpeed=0;
+                  chan[i].volSpeedTarget=-1;
+                }
                 dispatchCmd(DivCommand(DIV_CMD_HINT_VOLUME,i,chan[i].volume>>8));
                 dispatchCmd(DivCommand(DIV_CMD_VOLUME,i,chan[i].volume>>8));
                 dispatchCmd(DivCommand(DIV_CMD_HINT_VOL_SLIDE,i,0));
               }
             }
             // stop sliding if we reach maximum/minimum volume
-            // there isn't a compat flag for this yet... sorry...
             if (chan[i].volume>chan[i].volMax) {
               chan[i].volume=chan[i].volMax;
-              chan[i].volSpeed=0;
-              chan[i].volSpeedTarget=-1;
+              // COMPAT FLAG: don't stop volume slides after reaching target
+              if (!song.compatFlags.noVolSlideReset) {
+                chan[i].volSpeed=0;
+                chan[i].volSpeedTarget=-1;
+              }
               dispatchCmd(DivCommand(DIV_CMD_HINT_VOLUME,i,chan[i].volume>>8));
               dispatchCmd(DivCommand(DIV_CMD_VOLUME,i,chan[i].volume>>8));
               dispatchCmd(DivCommand(DIV_CMD_HINT_VOL_SLIDE,i,0));
             } else if (chan[i].volume<0) {
-              chan[i].volSpeed=0;
+              // COMPAT FLAG: don't stop volume slides after reaching target
+              if (!song.compatFlags.noVolSlideReset) {
+                chan[i].volSpeed=0;
+                chan[i].volSpeedTarget=-1;
+              }
               dispatchCmd(DivCommand(DIV_CMD_HINT_VOL_SLIDE,i,0));
               // COMPAT FLAG: legacy volume slides
               // - sets volume to max once a vol slide down has finished (thus setting volume to volMax+1)
@@ -2259,7 +2269,6 @@ bool DivEngine::nextTick(bool noAccum, bool inhibitLowLat) {
               } else {
                 chan[i].volume=0;
               }
-              chan[i].volSpeedTarget=-1;
               dispatchCmd(DivCommand(DIV_CMD_VOLUME,i,chan[i].volume>>8));
               dispatchCmd(DivCommand(DIV_CMD_HINT_VOLUME,i,chan[i].volume>>8));
             } else {
diff --git a/src/engine/song.cpp b/src/engine/song.cpp
index 91ec6b440..5cb472999 100644
--- a/src/engine/song.cpp
+++ b/src/engine/song.cpp
@@ -1165,6 +1165,7 @@ void DivCompatFlags::setDefaults() {
   oldAlwaysSetVolume=false;
   oldSampleOffset=false;
   oldCenterRate=true;
+  noVolSlideReset=false;
 }
 
 bool DivCompatFlags::areDefaults() {
@@ -1250,6 +1251,7 @@ bool DivCompatFlags::readData(SafeReader& reader) {
   CHECK_AND_LOAD_BOOL(oldAlwaysSetVolume);
   CHECK_AND_LOAD_BOOL(oldSampleOffset);
   CHECK_AND_LOAD_BOOL(oldCenterRate);
+  CHECK_AND_LOAD_BOOL(noVolSlideReset);
 
   return true;
 }
@@ -1324,6 +1326,7 @@ void DivCompatFlags::putData(SafeWriter* w) {
   CHECK_AND_STORE_BOOL(oldAlwaysSetVolume);
   CHECK_AND_STORE_BOOL(oldSampleOffset);
   CHECK_AND_STORE_BOOL(oldCenterRate);
+  CHECK_AND_STORE_BOOL(noVolSlideReset);
 
   String data=c.toString();
   w->write("CFLG",4);
diff --git a/src/engine/song.h b/src/engine/song.h
index 828e52304..f40fdba37 100644
--- a/src/engine/song.h
+++ b/src/engine/song.h
@@ -255,6 +255,7 @@ struct DivCompatFlags {
   bool oldSampleOffset;
   // new flags as of dev240
   bool oldCenterRate;
+  bool noVolSlideReset;
 
   void setDefaults();
   bool areDefaults();
diff --git a/src/gui/compatFlags.cpp b/src/gui/compatFlags.cpp
index 1b05e0063..5403394f1 100644
--- a/src/gui/compatFlags.cpp
+++ b/src/gui/compatFlags.cpp
@@ -426,6 +426,12 @@ void FurnaceGUI::drawCompatFlags() {
         if (ImGui::IsItemHovered()) {
           ImGui::SetTooltip(_("when enabled, the slide effect will not be disabled after it reaches its target."));
         }
+        if (ImGui::Checkbox(_("Don't reset volume slides after reaching target"),&e->song.compatFlags.noVolSlideReset)) {
+          MARK_MODIFIED;
+        }
+        if (ImGui::IsItemHovered()) {
+          ImGui::SetTooltip(_("when enabled, volume slide speeds will not be reset after reaching target or bounds."));
+        }
         if (ImGui::Checkbox(_("Continuous vibrato"),&e->song.compatFlags.continuousVibrato)) {
           MARK_MODIFIED;
         }