From 175069d6bf17876e97397023abc5309088041d2d Mon Sep 17 00:00:00 2001
From: Adrian Conlon <98398945+AdrianConlon@users.noreply.github.com>
Date: Fri, 2 May 2025 20:18:04 +0100
Subject: [PATCH] More Z80 timing fixes

---
 Z80/Z80.HarteTest/Checker.cs | 22 ++++++++++++++++--
 Z80/Z80.HarteTest/Test.cs    |  2 +-
 Z80/Z80.cs                   | 43 ++++++++++++++++++++++--------------
 3 files changed, 48 insertions(+), 19 deletions(-)

diff --git a/Z80/Z80.HarteTest/Checker.cs b/Z80/Z80.HarteTest/Checker.cs
index a0b3c36..cfc791a 100644
--- a/Z80/Z80.HarteTest/Checker.cs
+++ b/Z80/Z80.HarteTest/Checker.cs
@@ -333,10 +333,10 @@
         private void InitialiseState(Test test)
         {
             var initial = test.Initial ?? throw new InvalidOperationException("Test cannot have an invalid initial state");
-            this.InitialiseState(initial);
+            this.InitialiseState(initial, test.AvailablePorts());
         }
 
-        private void InitialiseState(State state)
+        private void InitialiseState(State state, IEnumerable<Port> ports)
         {
             var runner = this.Runner;
             var cpu = runner.CPU;
@@ -390,6 +390,24 @@
                 var value = (byte)entry[1];
                 runner.Poke(address, value);
             }
+
+            foreach (var port in ports)
+            {
+                var address = new Register16(port.Address).Low;
+                var value = port.Value;
+                if (port.Type == "r")
+                {
+                    cpu.Ports.WriteInputPort(address, value);
+                }
+                else if (port.Type == "w")
+                {
+                    cpu.Ports.WriteOutputPort(address, value);
+                }
+                else
+                {
+                    throw new InvalidOperationException($"Unknown port action type: {port.Type}");
+                }
+            }
         }
 
         private void AddActualCycle(EightBit.Register16 address, byte value, string action) => this.AddActualCycle(address.Word, value, action);
diff --git a/Z80/Z80.HarteTest/Test.cs b/Z80/Z80.HarteTest/Test.cs
index 5016881..44b4442 100644
--- a/Z80/Z80.HarteTest/Test.cs
+++ b/Z80/Z80.HarteTest/Test.cs
@@ -29,7 +29,7 @@
         {
             if (this.Ports is null)
             {
-                throw new InvalidOperationException("Ports have not been initialised");
+                yield break;
             }
 
             foreach (var port in this.Ports)
diff --git a/Z80/Z80.cs b/Z80/Z80.cs
index 9e2484e..f5651be 100644
--- a/Z80/Z80.cs
+++ b/Z80/Z80.cs
@@ -19,6 +19,8 @@ namespace Z80
 
         private readonly InputOutput _ports;
 
+        public InputOutput Ports => this._ports;
+
         private readonly Register16[] _accumulatorFlags = [new Register16(), new Register16()];
         private readonly Register16[][] _registers =
         [
@@ -504,8 +506,16 @@ namespace Z80
             var returned = base.MemoryRead();
             this.RaiseRD();
             this.RaiseMREQ();
-            if (this.M1.Raised())
+            if (this.M1.Lowered())
+            {
+                this.Bus.Address.Assign(this.REFRESH, this.IV);
+                this.LowerRFSH();
                 this.Tick();
+                this.LowerMREQ();
+                this.RaiseMREQ();
+                this.RaiseRFSH();
+            }
+            this.Tick();
             return returned;
         }
 
@@ -1509,6 +1519,7 @@ namespace Z80
                                             break;
                                         case 3: // LD SP,HL
                                             this.SP.Assign(this.HL2());
+                                            this.Tick(2);
                                             break;
                                         default:
                                             throw new NotSupportedException("Invalid operation mode");
@@ -1695,15 +1706,6 @@ namespace Z80
             this.LowerM1();
             var returned = this.MemoryRead(this.PC);
             this.RaiseM1();
-
-            this.Bus.Address.Assign(this.REFRESH, this.IV);
-            this.LowerRFSH();
-            this.Tick();
-            this.LowerMREQ();
-            this.RaiseMREQ();
-            this.RaiseRFSH();
-            this.Tick();
-
             return returned;
         }
 
@@ -1766,9 +1768,9 @@ namespace Z80
         protected sealed override bool ReturnConditionalFlag(int flag)
         {
             var condition = this.ConvertCondition(flag);
+            this.Tick();
             if (condition)
             {
-                this.Tick();
                 this.Return();
             }
             return condition;
@@ -2029,11 +2031,18 @@ namespace Z80
             ++this.Bus.Address.Word;
             this.MEMPTR.High = this.MemoryRead();
             this.Tick();
-            this.MemoryWrite(exchange.High);
-            exchange.High = this.MEMPTR.High;
             --this.Bus.Address.Word;
-            this.MemoryWrite(exchange.Low);
+            this.Tick();
+            this.Bus.Data = exchange.Low;
             exchange.Low = this.MEMPTR.Low;
+            this.MemoryUpdate(1);
+            this.Tick();
+            ++this.Bus.Address.Word;
+            this.Tick();
+            this.Bus.Data = exchange.High;
+            exchange.High = this.MEMPTR.High;
+            this.MemoryUpdate(1);
+            this.Tick(3);
         }
 
         private void BlockCompare(Register16 source, ushort counter)
@@ -2265,18 +2274,20 @@ namespace Z80
         {
             this.Bus.Address.Assign(port, this.Bus.Data = this.A);
             this.MEMPTR.Assign(this.Bus.Address);
-            ++this.MEMPTR.Low;
+            ++this.MEMPTR.Word;
             this.ReadPort();
         }
 
         private void ReadPort()
         {
-            this.Tick();
+            this.Tick(2);
             this.LowerIORQ();
             this.LowerRD();
             this.Bus.Data = this._ports.Read(this.Bus.Address.Low);
+            this.Tick();
             this.RaiseRD();
             this.RaiseIORQ();
+            this.Tick();
         }
     }
 }