public SICEvent(Instruction inst, int PC)
{
this.instruction = inst;
this.Continue = true;
this.PC = PC;
this.Ex = null;
this.Message = null;
}
public SICEvent(Instruction inst, int PC, Exception ex, string message)
{
this.instruction = inst;
this.Continue = false;
this.PC = PC;
this.Ex = ex;
this.Message = message;
}
public bool Step()
{
this.devicewrite = false;
current = getInstruction();
SICEvent instEvent = new SICEvent(current, ProgramCounter);
PreInstructionHook(instEvent);
if (!instEvent.Continue)
return false;
current.addrof = ProgramCounter;
IncrementPC(current);
if (current.twobyte)
{
DoTwoBye(current);
lastInstruction = current;
instEvent = new SICEvent(lastInstruction, ProgramCounter);
PostInstructionHook(instEvent);
if (!instEvent.Continue)
return false;
return true;
}
int calcaddr, memval;
calcaddr = GetAddress(current);
current.calculatedaddr = calcaddr;
try
{
memval = GetData(current);
}
catch (IndexOutOfRangeException ex)
{
throw new IndexOutOfRangeException(string.Format("Error: Instruction at 0x{0:X3} references memory that's out of range (0x{1:X3}).", current.addrof, calcaddr), ex);
}
try
{
switch ((OpCode)current.opcode)
{
case OpCode.ADD:
RegisterA += memval;
break;
case OpCode.SUB:
RegisterA -= memval;
break;
case OpCode.MUL:
RegisterA *= memval;
break;
case OpCode.DIV:
RegisterA /= memval;
break;
case OpCode.COMP:
Comp(RegisterA, memval);
break;
case OpCode.J:
ProgramCounter = calcaddr;
break;
case OpCode.JLT:
if (StatusWord == -1)
ProgramCounter = calcaddr;
break;
case OpCode.JGT:
if (StatusWord == 1)
ProgramCounter = calcaddr;
break;
case OpCode.JEQ:
if (StatusWord == 0)
ProgramCounter = calcaddr;
break;
case OpCode.STA:
StoreInt(calcaddr, RegisterA);
break;
case OpCode.STB:
StoreInt(calcaddr, RegisterB);
break;
case OpCode.STL:
StoreInt(calcaddr, RegisterL);
break;
case OpCode.STS:
StoreInt(calcaddr, RegisterS);
break;
case OpCode.STT:
StoreInt(calcaddr, RegisterT);
break;
case OpCode.STX:
StoreInt(calcaddr, RegisterX);
break;
case OpCode.LDB:
RegisterB = memval;
break;
case OpCode.LDX:
RegisterX = memval;
break;
case OpCode.LDA:
RegisterA = memval;
break;
case OpCode.LDL:
RegisterL = memval;
break;
case OpCode.LDS:
RegisterS = memval;
break;
case OpCode.LDT:
RegisterT = memval;
break;
case OpCode.TIX:
RegisterX++;
Comp(RegisterX, memval);
break;
case OpCode.JSUB:
RegisterL = ProgramCounter;
ProgramCounter = calcaddr;
break;
case OpCode.RSUB:
ProgramCounter = RegisterL;
break;
case OpCode.LDCH:
byte[] regA = BitConverter.GetBytes(RegisterA);
byte[] memChar = BitConverter.GetBytes(memval);
byte[] newVal = { memChar[2], regA[1], regA[2], regA[3] };
RegisterA = BitConverter.ToInt32(newVal, 0);
break;
case OpCode.STCH:
byte[] regiA = BitConverter.GetBytes(RegisterA);
memory[calcaddr] = regiA[0];
MemoryChangedHook(calcaddr, 1);
break;
case OpCode.RD:
case OpCode.TD:
case OpCode.WD:
devicewrite = true;
if (!DoDevice(current.opcode, memval))
{
ProgramCounter -= 3;
return false;
}
break;
case OpCode.AND:
RegisterA = RegisterA & memval;
break;
case OpCode.OR:
RegisterA = RegisterA | memval;
break;
default:
int location = ProgramCounter;
if (current.extended)
location -= 4;
else
location -= 3;
throw new ArgumentException(string.Format("Error: Instruction at 0x{0} not a recognized opcode.", !current.extended ? location.ToString("X3") : location.ToString("X4")));
}
}
catch (IndexOutOfRangeException ex)
{
throw new IndexOutOfRangeException(string.Format("Error: Instruction at 0x{0:X3} references memory that's out of range (0x{1:X3}).", ProgramCounter - 3, calcaddr), ex);
}
lastInstruction = current;
instEvent = new SICEvent(lastInstruction, ProgramCounter);
PostInstructionHook(instEvent);
if (!instEvent.Continue)
return false;
return true;
}
public void IncrementPC(Instruction current)
{
if (current.twobyte)
ProgramCounter += 2;
else if (current.extended)
ProgramCounter += 4;
else
ProgramCounter += 3;
}
public int GetData(Instruction current)
{
int address = GetAddress(current);
int memval;
if (current.immediate && !current.indirect)
{
if (!current.pcrel)
{ // Immediate mode combined with an addressing mode gets you the address as data. See Beck, p61
memval = current.address;
if (current.extended)
{
if ((memval & 0x80000) > 0)
memval = unchecked((int)((memval & 0xFFFFF) + 0xFFF00000));
}
else
{
if ((memval & 0x800) > 0)
memval = unchecked((int)((memval & 0xFFF) + 0xFFFFF000));
}
}
else if (current.baserel)
memval = RegisterB + current.address;
else
memval = ProgramCounter + current.address;
}
else
{
memval = GetMemoryValue(address);
}
return memval;
}
public int GetAddress(Instruction current)
{
int calcaddr;
if (current.baserel)
calcaddr = RegisterB + current.address;
else if (current.extended)
calcaddr = current.address;
else
calcaddr = ProgramCounter + current.address;
if (!current.immediate && current.indirect)
{
calcaddr = GetMemoryValue(calcaddr);
}
if (current.indexed)
{
calcaddr += RegisterX;
}
return calcaddr;
}
public void DoTwoBye(Instruction current)
{
Register r1 = current.r1;
Register r2 = current.r2;
switch (current.opcode)
{
case OpCode.ADDR:
SetRegisterValue(r2, (GetRegisterValue(r2) + GetRegisterValue(r1)));
break;
case OpCode.CLEAR:
SetRegisterValue(r1, 0);
break;
case OpCode.COMPR:
Comp(GetRegisterValue(r1), GetRegisterValue(r2));
break;
case OpCode.DIVR:
SetRegisterValue(r2, (GetRegisterValue(r2) / GetRegisterValue(r1)));
break;
case OpCode.MULR:
SetRegisterValue(r2, (GetRegisterValue(r2) * GetRegisterValue(r1)));
break;
case OpCode.RMO:
SetRegisterValue(r2, GetRegisterValue(r1));
break;
case OpCode.SUBR:
SetRegisterValue(r2, (GetRegisterValue(r2) - GetRegisterValue(r1)));
break;
case OpCode.TIXR:
RegisterX++;
Comp(RegisterX, GetRegisterValue(r1));
break;
case OpCode.SHIFTL:
uint lshift = (uint)GetRegisterValue(r1);
for (int i = 0; i < ((int)r2) + 1; i++)
{
lshift = lshift << 1;
if ((lshift & 0x01000000) > 0)
lshift = (lshift | 0x01);
lshift = lshift & 0x00FFFFFF;
}
SetRegisterValue(r1, (int)lshift);
break;
case OpCode.SHIFTR:
uint rshift = (uint)GetRegisterValue(r1);
for (int i = 0; i < ((int)r2) + 1; i++)
{
bool ones = (rshift & 0x1) > 0;
rshift = rshift >> 1;
if (ones)
rshift = (rshift | 0x800000);
}
SetRegisterValue(r1, (int)rshift);
break;
}
}