public void Execute(string function)
{
// get the current function
Function?currentFunction = null;
foreach (Function f in _functions)
{
if (f.Name == function)
{
currentFunction = f;
break;
}
}
if (currentFunction.HasValue == false)
{
throw new ArgumentException("Function not found: " + function);
}
int instructionPtr = 0;
byte[] code = currentFunction.Value.Code;
uint codeOffset = currentFunction.Value.CodeOffset;
while (instructionPtr < code.Length)
{
byte op = code[instructionPtr++];
int param;
Parameter[] functionParams;
switch (op)
{
case 0x00: // SitnSpin
// do nothing
break;
case 0x02: // CallSysFunctionV
param = getIntFromBytes(code, ref instructionPtr);
functionParams = buildParameterArray();
SheepMachine.CallVoidSystemFunction(Imports[param].Name, functionParams);
_state.PushStack(0);
break;
case 0x03: // CallSysFunctionI
param = getIntFromBytes(code, ref instructionPtr);
functionParams = buildParameterArray();
_state.PushStack(SheepMachine.CallIntSystemFunction(Imports[param].Name, functionParams));
break;
case 0x05: // CallSysFunctionS
param = getIntFromBytes(code, ref instructionPtr);
functionParams = buildParameterArray();
SheepMachine.CallStringSystemFunction(Imports[param].Name, functionParams);
_state.PushString(0);
break;
case 0x06: // Branch
param = getIntFromBytes(code, ref instructionPtr);
instructionPtr = param - (int)codeOffset;
break;
case 0x08: // BranchIfZero
param = getIntFromBytes(code, ref instructionPtr);
if (_state.PeekStack().Type != ParameterType.Integer)
{
throw new InvalidOperationException("stack is bad");
}
if (_state.PopStack().Integer == 0)
{
instructionPtr = param - (int)codeOffset;
}
break;
case 0x09: // BeginWait
// do nothing
break;
case 0x0A: // EndWait
// do nothing
break;
case 0x0B: // ReturnV
return;
case 0x13: // PushI
param = getIntFromBytes(code, ref instructionPtr);
_state.PushStack(param);
break;
case 0x15: // PushS
param = getIntFromBytes(code, ref instructionPtr);
_state.PushString(param);
break;
case 0x16: // Pop
_state.PopStack();
break;
case 0x21: // IsEqualI
if (_state.PeekStack().Type != ParameterType.Integer ||
_state.PeekStack().Type != ParameterType.Integer)
{
throw new InvalidOperationException("IsLessI found two non-integers on the stack");
}
if (_state.PopStack().Integer == _state.PopStack().Integer)
{
_state.PushStack(1);
}
else
{
_state.PushStack(0);
}
break;
case 0x27: // IsLessI
if (_state.PeekStack().Type != ParameterType.Integer ||
_state.PeekStack().Type != ParameterType.Integer)
{
throw new InvalidOperationException("IsLessI found two non-integers on the stack");
}
if (_state.PopStack().Integer >= _state.PopStack().Integer)
{
_state.PushStack(1);
}
else
{
_state.PushStack(0);
}
break;
case 0x2D:
param = getIntFromBytes(code, ref instructionPtr);
_state.PushStack((float)param);
break;
case 0x30:
// do nothing
break;
case 0x31:
// do nothing
break;
case 0x33: // GetString
{
if (_state.PeekStack().Type != ParameterType.String)
{
throw new InvalidOperationException("GetString failed because value on stack isn't a string");
}
param = _state.PopStack().Integer;
Parameter p = new Parameter();
p.Type = ParameterType.String;
p.Integer = param;
p.String = Constants[_constantOffsetIndexMap[param]];
_state.PushStack(p);
}
break;
default:
throw new NotImplementedException("Instruction " +
op.ToString("X") + " not implemented");
}
}
return;
}
