From 7dfd19de2b6b1e50ebe770aa907895f7c3c46672 Mon Sep 17 00:00:00 2001
From: Asnivor <coding@asnitech.co.uk>
Date: Mon, 4 Jun 2018 17:11:12 +0100
Subject: [PATCH] ZXHawk: Fix memory contention lookup overflow

---
 .../Computers/SinclairSpectrum/Machine/CPUMonitor.cs        | 2 +-
 .../Computers/SinclairSpectrum/Machine/ULA.cs               | 6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/CPUMonitor.cs b/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/CPUMonitor.cs
index e345c44c4f..8cfd43c657 100644
--- a/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/CPUMonitor.cs
+++ b/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/CPUMonitor.cs
@@ -109,7 +109,7 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
                 }
 
                 if (_machine.IsContended(addr))
-                    _cpu.TotalExecutedCycles += _machine.ULADevice.GetContentionValue();
+                    _cpu.TotalExecutedCycles += _machine.ULADevice.GetContentionValue((int)(_machine.CurrentFrameCycle + 1));
             }
         }
 
diff --git a/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/ULA.cs b/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/ULA.cs
index 72bd3bc3ba..59abd58290 100644
--- a/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/ULA.cs
+++ b/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/ULA.cs
@@ -752,7 +752,11 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
         /// <returns></returns>
         public int GetContentionValue()
         {
-            return RenderingTable.Renderer[_machine.CurrentFrameCycle].ContentionValue;
+            var f = _machine.CurrentFrameCycle;
+            if (f >= FrameCycleLength)
+                f -= FrameCycleLength;
+
+            return RenderingTable.Renderer[f].ContentionValue;
         }
 
         /// <summary>