From 592a3f102a6630cbc22f8d12285b1f13c5bd0640 Mon Sep 17 00:00:00 2001
From: tildearrow <me@tildearrow.org>
Date: Sun, 29 Oct 2023 02:45:15 -0500
Subject: [PATCH] C64: tiny fix to old test/gate/special compat

---
 src/engine/instrument.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/engine/instrument.cpp b/src/engine/instrument.cpp
index 61423b6d1..d2899d4ff 100644
--- a/src/engine/instrument.cpp
+++ b/src/engine/instrument.cpp
@@ -3478,8 +3478,14 @@ void DivInstrument::convertC64SpecialMacro() {
   }
   
   // merge ex3 into ex4
-  for (int i=0; i<maxLen; i++) {
-    std.ex4Macro.val[i]|=(std.ex3Macro.val[i]&3)<<1;
+  if (std.ex3Macro.len>0) {
+    for (int i=0; i<maxLen; i++) {
+      if (i>=std.ex3Macro.len) {
+        std.ex4Macro.val[i]|=(std.ex3Macro.val[std.ex3Macro.len-1]&3)<<1;
+      } else {
+        std.ex4Macro.val[i]|=(std.ex3Macro.val[i]&3)<<1;
+      }
+    }
   }
   std.ex4Macro.len=maxLen;