private static void PushDupPop(int times)
{
var compiler = new BytecodeCompiler();
for (int k = 0; k < times; k++)
{
compiler.Push(k);
}
compiler.Dup(times);
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
DataWord value = new DataWord(times);
Assert.AreEqual(DataWord.Zero, machine.Stack.Pop());
for (int k = 0; k < times; k++)
{
value = value.Subtract(DataWord.One);
Assert.AreEqual(value, machine.Stack.Pop());
}
Assert.AreEqual(0, machine.Stack.Size);
}
public void GreaterThan()
{
BytecodeCompiler compiler = new BytecodeCompiler();
compiler.Push(2);
compiler.Push(2);
compiler.GreaterThan();
compiler.Push(1);
compiler.Push(0);
compiler.GreaterThan();
compiler.Push(0);
compiler.Push(1);
compiler.GreaterThan();
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
var stack = machine.Stack;
Assert.IsNotNull(stack);
Assert.AreEqual(3, stack.Size);
Assert.AreEqual(DataWord.Zero, stack.ElementAt(2));
Assert.AreEqual(DataWord.Zero, stack.ElementAt(1));
Assert.AreEqual(DataWord.One, stack.ElementAt(0));
}
public void MOV_Bonanza32()
{
var programText = new string[] {
"section .text",
"global _start",
"_start:",
"mov eax, 0x11112222 ; eax = 0x11112222",
"mov ax, 0x3333 ; eax = 0x11113333 (works, only low 16 bits changed)",
"mov al, 0x44 ; eax = 0x11113344 (works, only low 8 bits changed)",
"mov ah, 0x55 ; eax = 0x11115544 (works, only high 8 bits changed)",
"xor ah, ah ; eax = 0x11110044 (works, only high 8 bits cleared)",
"mov eax, 0x11112222 ; eax = 0x11112222",
"xor al, al ; eax = 0x11112200 (works, only low 8 bits cleared)",
"mov eax, 0x11112222 ; eax = 0x11112222",
"xor ax, ax ; eax = 0x11110000 (works, only low 16 bits cleared)"
};
var compiler = new BytecodeCompiler <UInt32>();
var compiled = compiler.Compile(programText, "UNIT_TEST");
var agent = new Agent(kernel, compiled.TextSegment, 0);
var ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0x11112222, agent.ReadExtendedRegister(Register.EAX));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0x11113333, agent.ReadExtendedRegister(Register.EAX));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0x11113344, agent.ReadExtendedRegister(Register.EAX));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0x11115544, agent.ReadExtendedRegister(Register.EAX));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0x11110044, agent.ReadExtendedRegister(Register.EAX));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0x11112222, agent.ReadExtendedRegister(Register.EAX));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0x11112200, agent.ReadExtendedRegister(Register.EAX));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0x11112222, agent.ReadExtendedRegister(Register.EAX)); // Program should have terminated on the second tick
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0x11110000, agent.ReadExtendedRegister(Register.EAX)); // Program should have terminated on the second tick
}
public void CompileReadKeyboardAsm()
{
var compiler = new BytecodeCompiler <UInt32>();
var sourceFileName = "./../../../../picovm/asm-src/read-keyboard32.asm";
Xunit.Assert.True(File.Exists(Path.Combine(System.Environment.CurrentDirectory, sourceFileName)), $"Cannot find file {sourceFileName} for test, current directory: {System.Environment.CurrentDirectory}");
var compilation = compiler.Compile(sourceFileName);
Xunit.Assert.Equal(0, compilation.Errors.Count);
}
public void CompileHelloWorldLinux64Asm()
{
var compiler = new BytecodeCompiler <UInt64>();
var sourceFileName = "./../../../../picovm/asm-src/hello-world-linux64.asm";
Xunit.Assert.True(File.Exists(Path.Combine(System.Environment.CurrentDirectory, sourceFileName)), $"Cannot find file {sourceFileName} for test, current directory: {System.Environment.CurrentDirectory}");
var compilation = compiler.Compile(Path.Combine(System.Environment.CurrentDirectory, sourceFileName));
Xunit.Assert.Equal(0, compilation.Errors.Count);
}
public void MOV_REG_CON_Overlayed()
{
var programText = new string[] {
"section .text",
"global _start",
"_start:",
"MOV EAX, 4294967295", // copy the value 11111111111111111111111111111111 into eax
"MOV AX, 0", // copy the value 0000000000000000 into ax
"MOV AH, 170", // copy the value 10101010 (0xAA) into ah
"MOV AL, 85", // copy the value 01010101 (0x55) into al
"MOV EAX, 0", // copy the value 11111111111111111111111111111111 into eax
"END"
};
var compiler = new BytecodeCompiler <UInt32>();
var compiled = compiler.Compile(programText, "UNIT_TEST");
var agent = new Agent(kernel, compiled.TextSegment, 0);
var ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0xFFFFFFFF, agent.ReadExtendedRegister(Register.EAX));
Xunit.Assert.Equal((ushort)0xFFFF, agent.ReadRegister(Register.AX));
Xunit.Assert.Equal((byte)0xFF, agent.ReadHalfRegister(Register.AH));
Xunit.Assert.Equal((byte)0xFF, agent.ReadHalfRegister(Register.AL));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0xFFFF0000, agent.ReadExtendedRegister(Register.EAX));
Xunit.Assert.Equal((uint)0, agent.ReadRegister(Register.AX));
Xunit.Assert.Equal((uint)0, agent.ReadHalfRegister(Register.AH));
Xunit.Assert.Equal((uint)0, agent.ReadHalfRegister(Register.AL));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0xFFFFAA00, agent.ReadExtendedRegister(Register.EAX));
Xunit.Assert.Equal((uint)170, agent.ReadHalfRegister(Register.AH));
Xunit.Assert.Equal((uint)0, agent.ReadHalfRegister(Register.AL));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0xFFFFAA55, agent.ReadExtendedRegister(Register.EAX));
Xunit.Assert.Equal((uint)170, agent.ReadHalfRegister(Register.AH));
Xunit.Assert.Equal((uint)85, agent.ReadHalfRegister(Register.AL));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)0, agent.ReadExtendedRegister(Register.EAX));
ret = agent.Tick();
Xunit.Assert.NotNull(ret);
Xunit.Assert.Equal(0, ret); // Program should have terminated on the second tick
}
public void PUSH_POP_Overlayed()
{
var programText = new string[] {
"section .text",
"global _start",
"_start:",
"PUSH 4294945365", // push the value 1111 1111 1111 1111 1010 1010 0101 0101 (FFFF AA55) onto the stack
"POP EAX", // pop it back into eax
"PUSH 2863315917", // push the value 1010 1010 1010 1010 1011 1011 1100 1101 (AAAA BBCD) onto the stack
"POP EAX", // pop it back into eax
"END"
};
var compiler = new BytecodeCompiler <UInt32>();
var compiled = compiler.Compile(programText, "UNIT_TEST");
var agent = new Agent(kernel, compiled.TextSegment, 0);
Xunit.Assert.Equal((uint)65535, agent.StackPointer);
var ret = agent.Tick();
// PUSH 4294945365
Xunit.Assert.Null(ret);
agent.Dump();
Xunit.Assert.Equal((uint)(65535 - 4), agent.StackPointer);
Xunit.Assert.Equal(4294945365, agent.StackPeek32());
Xunit.Assert.Equal((uint)0, agent.ReadExtendedRegister(Register.EAX));
// POP EAX #1
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)(65535), agent.StackPointer);
Xunit.Assert.Equal((uint)4294945365, agent.ReadExtendedRegister(Register.EAX));
// PUSH 2863315917
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)(65535 - 4), agent.StackPointer);
Xunit.Assert.Equal(2863315917, agent.StackPeek32());
Xunit.Assert.Equal((uint)4294945365, agent.ReadExtendedRegister(Register.EAX));
// POP EAX #2
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((uint)(65535), agent.StackPointer);
Xunit.Assert.Equal((uint)2863315917, agent.ReadExtendedRegister(Register.EAX));
// END
ret = agent.Tick();
Xunit.Assert.NotNull(ret);
Xunit.Assert.Equal(0, ret); // Program should have terminated on the second tick
}
private static void PushPop(byte[] bytes)
{
BytecodeCompiler compiler = new BytecodeCompiler();
compiler.CompileAdjust(Bytecodes.Push1, bytes.Length - 1, bytes);
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
Assert.AreEqual(1, machine.Stack.Size);
Assert.AreEqual(new DataWord(bytes), machine.Stack.Pop());
}
public void Stop()
{
Machine machine = new Machine();
BytecodeCompiler compiler = new BytecodeCompiler();
compiler.Stop();
compiler.Push(1);
compiler.Push(2);
compiler.Push(3);
machine.Execute(compiler.ToBytes());
Assert.AreEqual(0, machine.Stack.Size);
}
public void Not()
{
DataWord dw1 = new DataWord(new byte[] { 0x0f, 0xf0, 0x0f, 0xf0, 0x0f, 0xf0 });
DataWord dw2 = new DataWord(new byte[] { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x0f, 0xf0, 0x0f, 0xf0, 0x0f });
var compiler = new BytecodeCompiler();
compiler.Push(dw1);
compiler.Not();
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
Assert.AreEqual(dw2, machine.Stack.Pop());
}
private static Machine PushSwap(int nswap)
{
BytecodeCompiler compiler = new BytecodeCompiler();
for (int k = 0; k < 17; k++)
{
compiler.Push(k);
}
compiler.Swap(nswap);
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
return(machine);
}
public void StoreAndLoadDataWord()
{
var compiler = new BytecodeCompiler();
compiler.Push(257);
compiler.Push(42);
compiler.MStore();
compiler.Push(43);
compiler.MLoad();
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
var stack = machine.Stack;
Assert.AreEqual(new DataWord(257 << 8), stack.Pop());
}
public void PushPushPopPop()
{
BytecodeCompiler compiler = new BytecodeCompiler();
compiler.Push(1);
compiler.Push(2);
compiler.Pop();
compiler.Pop();
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
var stack = machine.Stack;
Assert.IsNotNull(stack);
Assert.AreEqual(0, stack.Size);
}
public void InvalidTooLargeJump()
{
var compiler = new BytecodeCompiler();
compiler.Push(10000);
compiler.Jump();
compiler.Push(2);
compiler.Push(3);
compiler.Push(4);
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
var stack = machine.Stack;
Assert.AreEqual(0, stack.Size);
}
public void DivideByZero()
{
BytecodeCompiler compiler = new BytecodeCompiler();
compiler.Push(0);
compiler.Push(6);
compiler.Divide();
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
var stack = machine.Stack;
Assert.IsNotNull(stack);
Assert.AreEqual(1, stack.Size);
Assert.AreEqual(DataWord.Zero, stack.Pop());
}
public void MultiplyThreeTwo()
{
BytecodeCompiler compiler = new BytecodeCompiler();
compiler.Push(2);
compiler.Push(3);
compiler.Multiply();
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
var stack = machine.Stack;
Assert.IsNotNull(stack);
Assert.AreEqual(1, stack.Size);
Assert.AreEqual(new DataWord(6), stack.Pop());
}
public void SubtractThreeOne()
{
BytecodeCompiler compiler = new BytecodeCompiler();
compiler.Push(1);
compiler.Push(3);
compiler.Subtract();
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
var stack = machine.Stack;
Assert.IsNotNull(stack);
Assert.AreEqual(1, stack.Size);
Assert.AreEqual(DataWord.Two, stack.Pop());
}
public void MOV_Bonanza64()
{
var programText = new string[] {
"section .text",
"global _start",
"_start:",
"mov rax, 0x1111222233334444 ; rax = 0x1111222233334444",
"mov eax, 0x55556666 ; actual: rax = 0x0000000055556666",
"mov rax, 0x1111222233334444 ; rax = 0x1111222233334444",
"mov ax, 0x7777 ; rax = 0x1111222233337777 (works!)",
"mov rax, 0x1111222233334444 ; rax = 0x1111222233334444",
"xor eax, eax ; actual: rax = 0x0000000000000000",
" ; again, it wiped whole register"
};
var compiler = new BytecodeCompiler <UInt64>();
var compiled = compiler.Compile(programText, "UNIT_TEST");
var agent = new Agent64(kernel, compiled.TextSegment, 0);
var ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((ulong)0x1111222233334444, agent.ReadR64Register(Register.RAX));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((ulong)0x0000000055556666, agent.ReadR64Register(Register.RAX));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((ulong)0x1111222233334444, agent.ReadR64Register(Register.RAX));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((ulong)0x1111222233337777, agent.ReadR64Register(Register.RAX));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((ulong)0x1111222233334444, agent.ReadR64Register(Register.RAX));
ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal((ulong)0x0000000000000000, agent.ReadR64Register(Register.RAX));
}
public void StoreByte()
{
var compiler = new BytecodeCompiler();
compiler.Push(257);
compiler.Push(42);
compiler.MStore8();
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
var memory = machine.Memory;
Assert.IsNotNull(memory);
Assert.AreEqual(1, memory.GetByte(new DataWord(42)));
Assert.AreEqual(0, memory.GetByte(new DataWord(41)));
Assert.AreEqual(0, memory.GetByte(new DataWord(43)));
}
public void JumpPushes()
{
var compiler = new BytecodeCompiler();
compiler.Push(9);
compiler.Jump();
compiler.Push(2);
compiler.Push(3);
compiler.Push(4);
compiler.JumpDest();
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
var stack = machine.Stack;
Assert.AreEqual(0, stack.Size);
}
public void ConditionalJumpWhenTrue()
{
var compiler = new BytecodeCompiler();
compiler.Push(1);
compiler.Push(11);
compiler.JumpI();
compiler.Push(2);
compiler.Push(3);
compiler.Push(4);
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
var stack = machine.Stack;
Assert.AreEqual(0, stack.Size);
}
public void GetCoinbase()
{
Address coinbase = new Address();
ProgramEnvironment environment = ProgramEnvironment.Builder().Coinbase(coinbase).Build();
var compiler = new BytecodeCompiler();
compiler.Coinbase();
Machine machine = new Machine(environment);
machine.Execute(compiler.ToBytes());
var stack = machine.Stack;
Assert.IsNotNull(stack);
Assert.AreEqual(1, stack.Size);
Assert.AreEqual(new DataWord(coinbase.Bytes), stack.Pop());
}
public void PushesPc()
{
var compiler = new BytecodeCompiler();
compiler.Push(1);
compiler.Push(2);
compiler.Push(3);
compiler.Pc();
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
var stack = machine.Stack;
Assert.AreEqual(4, stack.Size);
Assert.AreEqual(new DataWord(6), stack.Pop());
Assert.AreEqual(DataWord.Three, stack.Pop());
Assert.AreEqual(DataWord.Two, stack.Pop());
Assert.AreEqual(DataWord.One, stack.Pop());
}
public void InvalidTooLargeJump()
{
var compiler = new BytecodeCompiler();
compiler.Push(10000);
compiler.Jump();
compiler.Push(2);
compiler.Push(3);
compiler.Push(4);
Machine machine = new Machine();
try
{
machine.Execute(compiler.ToBytes());
}
catch (InvalidOperationException ex)
{
Assert.AreEqual("Invalid jump destination", ex.Message);
}
}
public void ConditionalJumpWhenFalse()
{
var compiler = new BytecodeCompiler();
compiler.Push(0);
compiler.Push(11);
compiler.JumpI();
compiler.Push(2);
compiler.Push(3);
compiler.Push(4);
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
var stack = machine.Stack;
Assert.AreEqual(3, stack.Size);
Assert.AreEqual(new DataWord(4), stack.Pop());
Assert.AreEqual(new DataWord(3), stack.Pop());
Assert.AreEqual(new DataWord(2), stack.Pop());
}
public void StorageStoreLoad()
{
BytecodeCompiler compiler = new BytecodeCompiler();
compiler.Push(1);
compiler.SLoad();
compiler.Push(2);
compiler.Push(3);
compiler.SStore();
compiler.Push(3);
compiler.SLoad();
Machine machine = new Machine();
machine.Execute(compiler.ToBytes());
var stack = machine.Stack;
Assert.IsNotNull(stack);
Assert.AreEqual(2, stack.Size);
Assert.AreEqual(DataWord.Two, stack.Pop());
Assert.AreEqual(DataWord.Zero, stack.Pop());
}
public void JumpWithoutJumpDest()
{
var compiler = new BytecodeCompiler();
compiler.Push(9);
compiler.Jump();
compiler.Push(2);
compiler.Push(3);
compiler.Push(4);
compiler.Push(5);
Machine machine = new Machine();
try
{
machine.Execute(compiler.ToBytes());
Assert.Fail();
}
catch (InvalidOperationException ex)
{
Assert.AreEqual("Invalid jump destination", ex.Message);
}
}
static void Main(string[] args)
{
var options = new Options();
if (!CommandLine.Parser.Default.ParseArguments(args, options))
{
Environment.Exit(1);
}
var compiler = new BytecodeCompiler();
ExceptionOr <List <int> > result = Safe.Wrapper(compiler).FileToInstructions(options.InputFile);
if (result.HasFailed())
{
Console.Error.WriteLine("Failed to compile the instructions file: {0}", result.GetException().Message);
Environment.Exit(2);
}
if (options.ShowOpcodes)
{
foreach (var op in result.GetValue())
{
Console.Write("{0} ", op);
}
Console.WriteLine();
return;
}
if (options.ShowLayout)
{
var bytecode = new Bytecode();
int address = 0;
int length = result.GetValue().Count;
var opcodes = result.GetValue();
int i = 0;
while (i < length)
{
var insName = bytecode.FindNameByOpcode(opcodes[i]);
var numArgs = bytecode.GetNumArgs(opcodes[i]);
Console.Write("{0:0000}:\t{1} ", i, insName);
i++;
for (int j = 0; j < numArgs; j++)
{
Console.Write("{0} ", opcodes[i]);
i++;
}
Console.WriteLine();
}
Console.WriteLine();
return;
}
var interpreter = new VM.Interpreter();
if (options.Debugger != null)
{
var monitor = new Monitor();
monitor.InsertNewLineBefore = true;
interpreter.SetMonitor(monitor);
switch (options.Debugger)
{
case "tracer":
interpreter.Attach(new VM.Tracer());
break;
case "singlestep":
interpreter.Attach(new VM.SingleStepDebugger());
break;
default:
Console.Error.WriteLine("\"{0}\" is not a valid debugger. Use: \"tracer\", \"singlestep\"", options.Debugger);
Environment.Exit(3);
break;
}
}
var ins = result.GetValue();
if (ins.Count > 0)
{
interpreter.Run(result.GetValue(), 0);
}
}
private NeoChunk Compile(ChunkNode ast)
{
var compiler = new BytecodeCompiler(ast);
return(BuildNeoChunk(compiler.Compile()));
}
public void MOV_REG_CON_Simple()
{
var programText = new string[] {
"section .text",
"global _start",
"_start:",
" MOV EAX, 4294967295 ; copy the value 11111111111111111111111111111111 into eax",
" MOV AX, 0 ; copy the value 0000000000000000 into ax",
" MOV AH, 170 ; copy the value 10101010 (0xAA) into ah",
" MOV AL, 85 ; copy the value 01010101 (0x55) into al",
" MOV EBX, 5 ; copy the value 5 into ebx",
" MOV EAX, EBX ; copy the value in ebx into eax",
" PUSH 4 ; push 4 on the stack",
" PUSH EAX ; push eax (5) on the stack",
" PUSH 6 ; push 6 on the stack",
" POP EBX ; pop stack (6) into ebx",
" POP EBX ; pop stack (5) into ebx",
" POP [EBX] ; pop stack (4) into [ebx] memory location = 5",
" ADD [EBX], 10 ; add 10 to the value in [ebx] which would change 4 to 14",
" PUSH [EBX] ; push [ebx] memory location=5 value=14 onto the stack",
"END"
};
var compiler = new BytecodeCompiler <UInt32>();
var compiled = compiler.Compile(programText, "UNIT_TEST");
var agent = new Agent(kernel, compiled.TextSegment, 0);
var ret = agent.Tick();
Xunit.Assert.Null(ret);
Xunit.Assert.Equal(4294967295, agent.ReadExtendedRegister(Register.EAX));
ret = agent.Tick();
Xunit.Assert.Equal(0U, agent.ReadRegister(Register.AX));
ret = agent.Tick();
Xunit.Assert.Equal(170, agent.ReadHalfRegister(Register.AH));
ret = agent.Tick();
Xunit.Assert.Equal(85, agent.ReadHalfRegister(Register.AL));
ret = agent.Tick();
Xunit.Assert.Equal(5U, agent.ReadExtendedRegister(Register.EBX));
ret = agent.Tick();
Xunit.Assert.Equal(5U, agent.ReadExtendedRegister(Register.EAX));
Xunit.Assert.Equal(5U, agent.ReadExtendedRegister(Register.EBX));
ret = agent.Tick();
ret = agent.Tick();
ret = agent.Tick();
ret = agent.Tick();
Xunit.Assert.Equal(6U, agent.ReadExtendedRegister(Register.EBX));
ret = agent.Tick();
Xunit.Assert.Equal(5U, agent.ReadExtendedRegister(Register.EBX));
ret = agent.Tick();
Xunit.Assert.Equal(5U, agent.ReadExtendedRegister(Register.EBX));
ret = agent.Tick();
ret = agent.Tick();
ret = agent.Tick();
Xunit.Assert.NotNull(ret);
Xunit.Assert.Equal(0, ret); // Program should have terminated on the second tick
}