From 80a92b8b43bda8e322c0bdb19ec0dfebbca1b983 Mon Sep 17 00:00:00 2001
From: tildearrow <me@tildearrow.org>
Date: Sat, 4 Oct 2025 18:28:34 -0500
Subject: [PATCH] add option to remove unused patterns

---
 src/engine/song.cpp | 18 ++++++++++++++++++
 src/engine/song.h   |  1 +
 src/gui/gui.cpp     |  8 ++++++++
 3 files changed, 27 insertions(+)

diff --git a/src/engine/song.cpp b/src/engine/song.cpp
index 7e6fb5e6f..e457478e4 100644
--- a/src/engine/song.cpp
+++ b/src/engine/song.cpp
@@ -278,6 +278,24 @@ void DivSubSong::clearData() {
   ordersLen=1;
 }
 
+void DivSubSong::removeUnusedPatterns() {
+  for (int i=0; i<DIV_MAX_CHANS; i++) {
+    bool used[DIV_MAX_PATTERNS];
+    memset(used,0,DIV_MAX_PATTERNS*sizeof(bool));
+
+    for (int j=0; j<ordersLen; j++) {
+      used[orders.ord[i][j]]=true;
+    }
+
+    for (int j=0; j<DIV_MAX_PATTERNS; j++) {
+      if (!used[j] && pat[i].data[j]!=NULL) {
+        delete pat[i].data[j];
+        pat[i].data[j]=NULL;
+      }
+    }
+  }
+}
+
 void DivSubSong::optimizePatterns() {
   for (int i=0; i<DIV_MAX_CHANS; i++) {
     logD("optimizing channel %d...",i);
diff --git a/src/engine/song.h b/src/engine/song.h
index e13d8b101..ced8a7449 100644
--- a/src/engine/song.h
+++ b/src/engine/song.h
@@ -196,6 +196,7 @@ struct DivSubSong {
   void findLength(int loopOrder, int loopRow, double fadeoutLen, int& rowsForFadeout, bool& hasFFxx, std::vector<int>& orders, std::vector<DivGroovePattern>& grooves, int& length, int chans, int jumpTreatment, int ignoreJumpAtEnd, int firstPat=0);
 
   void clearData();
+  void removeUnusedPatterns();
   void optimizePatterns();
   void rearrangePatterns();
   void sortOrders();
diff --git a/src/gui/gui.cpp b/src/gui/gui.cpp
index 64de23ef3..de659e37a 100644
--- a/src/gui/gui.cpp
+++ b/src/gui/gui.cpp
@@ -6553,6 +6553,14 @@ bool FurnaceGUI::loop() {
               MARK_MODIFIED;
               ImGui::CloseCurrentPopup();
             }
+            if (ImGui::Button(_("Remove unused patterns"))) {
+              stop();
+              e->lockEngine([this]() {
+                e->curSubSong->removeUnusedPatterns();
+              });
+              MARK_MODIFIED;
+              ImGui::CloseCurrentPopup();
+            }
             if (ImGui::Button(_("Remove unused instruments"))) {
               stop();
               e->delUnusedIns();