From 48924bdfba1ff6ada0e1e9356ffa84a257e9a603 Mon Sep 17 00:00:00 2001
From: Nabile Rahmani <nabile13.pc@gmail.com>
Date: Thu, 29 Nov 2018 04:39:23 +0100
Subject: [PATCH] Handle endianness on sub-word CPU reads (fixes garbled text
 on test ROMs). - Added SD opcode for running some test ROMs. - Quit the
 debugger when the N64 is powered off.

---
 DotN64/CPU/VR4300/VR4300.OpCode.cs | 4 +++-
 DotN64/CPU/VR4300/VR4300.cs        | 7 +++++--
 DotN64/Diagnostics/Debugger.cs     | 3 ++-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/DotN64/CPU/VR4300/VR4300.OpCode.cs b/DotN64/CPU/VR4300/VR4300.OpCode.cs
index 7b1f672..5f175a8 100644
--- a/DotN64/CPU/VR4300/VR4300.OpCode.cs
+++ b/DotN64/CPU/VR4300/VR4300.OpCode.cs
@@ -61,7 +61,9 @@
             /// <summary>Load Byte.</summary>
             LB = 0b100000,
             /// <summary>Branch On Greater Than Zero.</summary>
-            BGTZ = 0b000111
+            BGTZ = 0b000111,
+            /// <summary>Store Doubleword.</summary>
+            SD = 0b111111
         }
     }
 }
diff --git a/DotN64/CPU/VR4300/VR4300.cs b/DotN64/CPU/VR4300/VR4300.cs
index 51257b1..c0a03c0 100644
--- a/DotN64/CPU/VR4300/VR4300.cs
+++ b/DotN64/CPU/VR4300/VR4300.cs
@@ -165,6 +165,7 @@ namespace DotN64.CPU
                 [Instruction.From(OpCode.J)] = i => Jump((PC & ~((ulong)(1 << 28) - 1)) | (i.Target << 2)),
                 [Instruction.From(OpCode.LB)] = i => Load(i, AccessSize.Byte),
                 [Instruction.From(OpCode.BGTZ)] = i => Branch(i, (rs, rt) => rs > 0),
+                [Instruction.From(OpCode.SD)] = i => Store(i, AccessSize.DoubleWord),
                 [Instruction.From(SpecialOpCode.ADD)] = i => GPR[i.RD] = (ulong)((int)GPR[i.RS] + (int)GPR[i.RT]),
                 [Instruction.From(SpecialOpCode.JR)] = i => Jump(GPR[i.RS]),
                 [Instruction.From(SpecialOpCode.SRL)] = i => GPR[i.RD] = (ulong)(int)((uint)GPR[i.RT] >> i.SA),
@@ -326,9 +327,11 @@ namespace DotN64.CPU
             switch (size)
             {
                 case AccessSize.Byte:
-                    return (byte)ReadSysAD(physicalAddress);
+                    physicalAddress &= ~0b11u;
+                    return (byte)(ReadSysAD(physicalAddress) >> (((int)address & 0b11 ^ -(int)CP0.Config.BE) << 3));
                 case AccessSize.HalfWord:
-                    return (ushort)ReadSysAD(physicalAddress);
+                    physicalAddress &= ~0b11u;
+                    return (ushort)(ReadSysAD(physicalAddress) >> (((int)address & 0b11 ^ (-(int)CP0.Config.BE << 1)) << 3));
                 case AccessSize.Word:
                     return ReadSysAD(physicalAddress);
                 case AccessSize.DoubleWord:
diff --git a/DotN64/Diagnostics/Debugger.cs b/DotN64/Diagnostics/Debugger.cs
index d16f8fa..1b8838f 100644
--- a/DotN64/Diagnostics/Debugger.cs
+++ b/DotN64/Diagnostics/Debugger.cs
@@ -39,6 +39,7 @@ namespace DotN64.Diagnostics
             [VR4300.Instruction.From(VR4300.OpCode.LW)] = InstructionFormat.I,
             [VR4300.Instruction.From(VR4300.OpCode.ORI)] = InstructionFormat.I,
             [VR4300.Instruction.From(VR4300.OpCode.SB)] = InstructionFormat.I,
+            [VR4300.Instruction.From(VR4300.OpCode.SD)] = InstructionFormat.I,
             [VR4300.Instruction.From(VR4300.OpCode.SH)] = InstructionFormat.I,
             [VR4300.Instruction.From(VR4300.OpCode.SLTI)] = InstructionFormat.I,
             [VR4300.Instruction.From(VR4300.OpCode.SLTIU)] = InstructionFormat.I,
@@ -296,7 +297,7 @@ namespace DotN64.Diagnostics
         {
             DebuggerStatus = debug ? Status.Debugging : Status.Running;
 
-            while (DebuggerStatus != Status.Stopped)
+            while (DebuggerStatus != Status.Stopped && nintendo64.Power == Switch.On)
             {
                 switch (DebuggerStatus)
                 {