Add MUL tests to the MC6809 core.

Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>

MC6809/MC6809.UnitTest/MC6809.UnitTest.csproj

@@ -85,6 +85,7 @@
     <Compile Include="RorTests.cs" />
     <Compile Include="ComTests.cs" />
     <Compile Include="LeaTests.cs" />
+    <Compile Include="MulTests.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\EightBit\EightBit.csproj">

MC6809/MC6809.UnitTest/MulTests.cs

@@ -0,0 +1,74 @@
+// <copyright file="MulTests.cs" company="Adrian Conlon">
+// Copyright (c) Adrian Conlon. All rights reserved.
+// </copyright>
+
+namespace EightBit
+{
+    using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+    [TestClass]
+    public class MulTests
+    {
+        private readonly Board board = new Board();
+        private readonly MC6809 cpu;
+
+        public MulTests() => this.cpu = this.board.CPU;
+
+        [TestInitialize]
+        public void Initialise()
+        {
+            this.board.RaisePOWER();
+            this.cpu.Step(); // Step over the reset
+        }
+
+        [TestCleanup]
+        public void Cleanup() => this.board.LowerPOWER();
+
+        // Multiply 0x0C with 0x64. Result is 0x04B0.
+        // The Zero flag is set if the 16-bit result is zero; cleared otherwise.
+        // The Carry flag is set equal to the new value of bit 7 in Accumulator B.
+        [TestMethod]
+        public void TestMUL_one()
+        {
+            this.board.Poke(0xb00, 0x3d);
+            this.cpu.CC = 0;
+            this.cpu.CC |= (byte)StatusBits.ZF;
+            this.cpu.A = 0xc;
+            this.cpu.B = 0x64;
+            this.cpu.PC.Word = 0xb00;
+
+            this.cpu.Step();
+
+            Assert.AreEqual(0x4b0, this.cpu.D.Word);
+            Assert.AreEqual(0x4, this.cpu.A);
+            Assert.AreEqual(0xb0, this.cpu.B);
+            Assert.AreEqual(0, this.cpu.Zero);
+            Assert.AreNotEqual(0, this.cpu.Carry);
+        }
+
+        // Multiply 0x0C with 0x00. Result is 0x0000.
+        // The Zero flag is set if the 16-bit result is zero; cleared otherwise.
+        // The Carry flag is set equal to the new value of bit 7 in Accumulator B.
+        [TestMethod]
+        public void TestMUL_two()
+        {
+            this.board.Poke(0xb00, 0x3d);
+            this.cpu.CC = 0;
+            this.cpu.CC &= (byte)~StatusBits.CF;
+            this.cpu.CC |= (byte)StatusBits.ZF;
+            this.cpu.A = 0xc;
+            this.cpu.B = 0x00;
+            this.cpu.PC.Word = 0xb00;
+
+            this.cpu.Step();
+
+            Assert.AreEqual(0, this.cpu.D.Word);
+            Assert.AreEqual(0, this.cpu.A);
+            Assert.AreEqual(0, this.cpu.B);
+            Assert.AreNotEqual(0, this.cpu.Zero);
+            Assert.AreEqual(0, this.cpu.Carry);
+        }
+    }
+}
+
+