public Context BeforeInstruction(Context ctx)
{
return(_tracer.BeforeInstruction(ctx));
}
public void Run(List <int> code, int main)
{
var ctx = new Context(code);
ctx.IP = main;
var opcode = ctx.Code[ctx.IP];
while (opcode != Bytecode.Halt && ctx.IP < ctx.Code.Count)
{
if (_debugger != null)
{
ctx = _debugger.BeforeInstruction(ctx);
}
ctx.IP++;
switch (opcode)
{
case Bytecode.Push:
{
var val = ctx.Code[ctx.IP++];
ctx.Stack.Push(val);
ctx.SP++;
}
break;
case Bytecode.IEqual:
{
var b = ctx.Stack.Pop();
var a = ctx.Stack.Pop();
ctx.SP--;
if (a == b)
{
ctx.Stack.Push(1);
}
else
{
ctx.Stack.Push(0);
}
}
break;
case Bytecode.ILessThan:
{
var b = ctx.Stack.Pop();
var a = ctx.Stack.Pop();
ctx.SP--;
if (a < b)
{
ctx.Stack.Push(1);
}
else
{
ctx.Stack.Push(0);
}
}
break;
case Bytecode.Jump:
{
ctx.IP = ctx.Code[ctx.IP++];
}
break;
case Bytecode.JumpTrue:
{
var addr = ctx.Code[ctx.IP++];
var val = ctx.Stack.Pop();
ctx.SP--;
if (val == 1)
{
ctx.IP = addr;
}
}
break;
case Bytecode.JumpFalse:
{
var addr = ctx.Code[ctx.IP++];
var val = ctx.Stack.Pop();
ctx.SP--;
if (val == 0)
{
ctx.IP = addr;
}
}
break;
case Bytecode.IAdd:
{
var b = ctx.Stack.Pop();
var a = ctx.Stack.Pop();
ctx.Stack.Push(a + b);
ctx.SP--;
}
break;
case Bytecode.ISub:
{
var b = ctx.Stack.Pop();
var a = ctx.Stack.Pop();
ctx.Stack.Push(a - b);
ctx.SP--;
}
break;
case Bytecode.IMult:
{
var b = ctx.Stack.Pop();
var a = ctx.Stack.Pop();
ctx.Stack.Push(a * b);
ctx.SP--;
}
break;
case Bytecode.IDiv:
{
var b = ctx.Stack.Pop();
var a = ctx.Stack.Pop();
ctx.Stack.Push(a / b);
ctx.SP--;
}
break;
case Bytecode.GStore:
{
var val = ctx.Stack.Pop();
ctx.SP--;
int addr = ctx.Code[ctx.IP];
ctx.IP++;
ctx.Globals[addr] = val;
}
break;
case Bytecode.GLoad:
{
int addr = ctx.Code[ctx.IP];
ctx.IP++;
int val = ctx.Globals[addr];
ctx.Stack.Push(val);
ctx.SP++;
}
break;
case Bytecode.Print:
{
var val = ctx.Stack.Pop();
ctx.SP--;
_monitor.Display(String.Format("{0}\n", val));
}
break;
case Bytecode.PrintChar:
{
var val = ctx.Stack.Pop();
ctx.SP--;
_monitor.Display(String.Format("{0}", (char)val));
}
break;
case Bytecode.Load:
{
var arg = ctx.Code[ctx.IP++];
var callArg = ctx.Stack[ctx.BP - (3 + arg)];
ctx.Stack.Push(callArg);
ctx.SP++;
}
break;
case Bytecode.Call:
{
var returnAddr = ctx.IP + 2;
var numArgs = ctx.Code[ctx.IP++];
var targetAddr = ctx.Code[ctx.IP++];
ctx.Stack.Push(ctx.BP);
ctx.Stack.Push(numArgs);
ctx.Stack.Push(returnAddr);
ctx.SP += 3;
ctx.BP = ctx.SP;
ctx.IP = targetAddr;
}
break;
case Bytecode.Ret:
{
// Copying the remaining parameters which are on the
// stack into an intermediate "backup" stack:
var backupStack = new List <int>();
var currentSP = ctx.SP;
for (int i = ctx.BP; i < currentSP; i++)
{
var val = ctx.Stack.Pop();
backupStack.Push(val);
ctx.SP--;
}
var returnAddr = ctx.Stack.Pop();
var numArgs = ctx.Stack.Pop();
ctx.BP = ctx.Stack.Pop();
ctx.SP -= 3;
// Cleaning up the stack
while (numArgs > 0)
{
ctx.Stack.Pop();
ctx.SP--;
numArgs -= 1;
}
// Restoring the stack from the "backup stack"
// This way we can return values from the "function":
while (backupStack.Count > 0)
{
ctx.Stack.Push(backupStack.Pop());
ctx.SP++;
}
backupStack.Clear();
ctx.IP = returnAddr;
}
break;
}
if (_debugger != null)
{
ctx = _debugger.AfterInstruction(ctx);
}
opcode = ctx.Code[ctx.IP];
}
}
