public ProgramCounter(int row, int col, PlayField playField)
{
Row = row;
Col = col;
_playField = playField;
Directions = new Dictionary <ProgramCounterDirection, Action> {
{ ProgramCounterDirection.Up, MoveUp },
{ ProgramCounterDirection.Down, MoveDown },
{ ProgramCounterDirection.Left, MoveLeft },
{ ProgramCounterDirection.Right, MoveRight },
};
}
static void Main(string[] args)
{
var debug = args.Any(arg => arg == "--debug");
var filename = args.FirstOrDefault(arg => !arg.StartsWith("--"));
if (filename == null)
{
Console.WriteLine("Usage: befunge <source.bf> [--debug]");
Environment.Exit(1);
}
if (!File.Exists(filename))
{
Console.WriteLine($"Invalid filename: {args[0]}");
Environment.Exit(1);
}
var source = File.OpenText(args[0]).ReadToEnd();
if (debug)
{
Console.Error.WriteLine(source);
}
if (debug)
{
Console.Error.WriteLine("Tokenizing...");
}
var tokenizer = new Tokenizer(source);
var tokens = tokenizer.Tokenize();
if (debug)
{
Console.Error.WriteLine("Creating the playing field...");
}
var field = new PlayField(tokens);
if (debug)
{
Console.Error.WriteLine("Running the VM...");
}
new VirtualMachine().Run(field, debug);
Console.WriteLine();
}
public void Run(PlayField playField, bool debug = false)
{
var stack = new Stack <long>();
var stringMode = false;
var randomForDirection = new Random();
var availableDirections = new[] {
ProgramCounterDirection.Up, ProgramCounterDirection.Down,
ProgramCounterDirection.Left, ProgramCounterDirection.Right,
};
var currentDirection = ProgramCounterDirection.Right;
while (true)
{
if (debug)
{
if (!(playField.Current is BlankToken))
{
Console.Error.WriteLine(
$"Stack: {string.Join(", ", stack.ToList())} ");
Console.Error.WriteLine(playField.Current);
}
}
if (stringMode)
{
if (playField.Current is QuoteToken)
{
stringMode = !stringMode;
}
else
{
stack.Push(playField.Current.AsCharToken().AsciiValue);
}
}
else
{
long a, b;
switch (playField.Current)
{
case AddToken t:
(a, b) = (stack.PopOrZero(), stack.PopOrZero());
stack.Push(a + b);
break;
case SubtractToken t:
(a, b) = (stack.PopOrZero(), stack.PopOrZero());
stack.Push(b - a);
break;
case MultiplyToken t:
(a, b) = (stack.PopOrZero(), stack.PopOrZero());
stack.Push(a * b);
break;
case DivideToken t:
(a, b) = (stack.PopOrZero(), stack.PopOrZero());
if (a != 0)
{
stack.Push(b / a);
}
else
{
stack.Push(
PromptForInt("Can't divide by zero. What result would you like?")
);
}
break;
case ModulusToken t:
(a, b) = (stack.PopOrZero(), stack.PopOrZero());
stack.Push(b % a);
break;
case NotToken t:
a = stack.PopOrZero();
stack.Push(a == 0 ? 1 : 0);
break;
case GreaterToken t:
(a, b) = (stack.PopOrZero(), stack.PopOrZero());
stack.Push(b > a ? 1 : 0);
break;
case RightToken t:
currentDirection = ProgramCounterDirection.Right;
break;
case LeftToken t:
currentDirection = ProgramCounterDirection.Left;
break;
case UpToken t:
currentDirection = ProgramCounterDirection.Up;
break;
case DownToken t:
currentDirection = ProgramCounterDirection.Down;
break;
case RandomToken t:
currentDirection =
availableDirections[randomForDirection.Next(availableDirections.Length)];
break;
case HorizontalIfToken t:
a = stack.PopOrZero();
currentDirection = a == 0
? ProgramCounterDirection.Right
: ProgramCounterDirection.Left;
break;
case VerticalIfToken t:
a = stack.PopOrZero();
currentDirection = a == 0
? ProgramCounterDirection.Down
: ProgramCounterDirection.Up;
break;
case QuoteToken t:
stringMode = !stringMode;
break;
case DuplicateToken t:
stack.Push(stack.PeekOrZero());
break;
case SwapToken t:
(a, b) = (stack.PopOrZero(), stack.PopOrZero());
stack.Push(a);
stack.Push(b);
break;
case PopToken t:
stack.PopOrZero();
break;
case OutputIntToken t:
Console.Write(stack.PopOrZero());
break;
case OutputCharToken t:
Console.Write(char.ConvertFromUtf32((int)stack.PopOrZero()));
break;
case JumpToken t:
playField.ProgramCounter.Move(currentDirection);
break;
case GetToken t:
(a, b) = (stack.PopOrZero(), stack.PopOrZero());
stack.Push(
playField.IsLegalPosition(a, b)
? playField[a, b].AsCharToken().AsciiValue
: 0
);
break;
case PutToken t:
long c;
(a, b, c) = (stack.PopOrZero(), stack.PopOrZero(), stack.PopOrZero());
char val = (char)c;
playField[a, b] = new CharToken(val, a, b);
break;
case InputIntToken t:
stack.Push(PromptForInt("Input a number"));
break;
case InputCharToken t:
stack.Push(PromptForChar("Input a character"));
break;
case NumberToken t:
stack.Push(t.Value);
break;
case BlankToken t:
break;
case HaltToken t:
return;
default:
throw new TokenizerException($"Unknown token: {playField.Current}");
}
}
playField.ProgramCounter.Move(currentDirection);
}
}
