From 0935b408ec5a62af5d75e5c38bc0c0a9cca31973 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ada=20Gottenstr=C3=A4ter?= <nunuu@gmx.net>
Date: Sun, 13 Jun 2021 11:22:07 +0200
Subject: [PATCH] Fix reversed assignment ops

---
 Gear/EmulationCore/InstructionDisassembler.cs |  4 ++--
 Gear/EmulationCore/InterpretedCog.cs          | 19 ++++++++++++-------
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/Gear/EmulationCore/InstructionDisassembler.cs b/Gear/EmulationCore/InstructionDisassembler.cs
index e2db3f0..c0f829f 100644
--- a/Gear/EmulationCore/InstructionDisassembler.cs
+++ b/Gear/EmulationCore/InstructionDisassembler.cs
@@ -115,11 +115,11 @@ private static string GetEffectCode(Propeller.MemoryManager memory, bool useShor
 
             if (useShortOpcodes)
             {
-                effect += "(" + ParsedAssignment.GetBasicInstruction().NameBrief + ")";
+                effect += "(" + ParsedAssignment.GetBasicInstruction().NameBrief + (ParsedAssignment.Swap ? ",reverse" : "") + ")";
             }
             else
             {
-                effect += ParsedAssignment.GetBasicInstruction().Name;
+                effect += ParsedAssignment.GetBasicInstruction().Name + (ParsedAssignment.Swap ? " REVERSE" : "");
             }
 
             if (!ParsedAssignment.Math)
diff --git a/Gear/EmulationCore/InterpretedCog.cs b/Gear/EmulationCore/InterpretedCog.cs
index b80b78b..be995b0 100644
--- a/Gear/EmulationCore/InterpretedCog.cs
+++ b/Gear/EmulationCore/InterpretedCog.cs
@@ -248,10 +248,10 @@ override public bool DoInstruction()
             byte op = Hub.DirectReadByte(PC++);
             frameFlag = FrameState.frameNone;
 
-            // Masked Memory Operations
+            // Math Operations
             if (op >= 0xE0)
             {
-                PushStack(BaseMathOp((byte)(op - 0xE0), false, PopStack()));
+                PushStack(BaseMathOp((byte)(op - 0xE0), false, false, PopStack()));
             }
             // Masked Memory Operations
             else if (op >= 0x80)
@@ -897,7 +897,7 @@ private void CogMemoryOp(uint mask, int lowestbit)
             }
         }
 
-        private uint BaseMathOp(byte op, bool inplace, uint initial)
+        private uint BaseMathOp(byte op, bool inplace, bool swap, uint initial)
         {
             // --- Unary Operators ---
             switch (op)
@@ -940,8 +940,13 @@ private uint BaseMathOp(byte op, bool inplace, uint initial)
 
             if (inplace)
             {
-                left = initial;
-                right = PopStack();
+                if (swap) {
+                    left = PopStack();
+                    right = initial;
+                } else {
+                    left = initial;
+                    right = PopStack();
+                }
             }
             else
             {
@@ -1196,9 +1201,9 @@ private uint InplaceEffect(uint originalValue)
             op &= 0x7F;
 
             // Use Main opcode set
-            if (op >= 0x40 && op <= 0x5F)
+            if (op >= 0x40)
             {
-                stored = result = BaseMathOp((byte)(op - 0x40), true, originalValue);
+                stored = result = BaseMathOp((byte)(op & 0x1F), true, (op & 0x20) != 0, originalValue);
             }
             else
             {