/// <summary>
/// Constructor.
/// </summary>
public Processor()
{
// Initialize the RAM with 64K
ram = new Memory(256 * 256);
// Initialize the internal Registers
instruction = new InstructionRegister();
programCounter = new Register16();
// Initialize the ALU Registers
a = new Register();
b = new Register();
c = new Register();
// Initialize the 8-bit General Purpose Registers
d = new Register();
e = new Register();
f = new Register();
g = new Register();
h = new Register();
xl = new Register();
xh = new Register();
// Initialize the 16-bit General Purpose Registers
m = new Register16();
j = new Register16();
sp = new Register16();
bp = new Register16();
y = new Register16();
z = new Register16();
// Initialize the Flags Register
flags = new Register();
flagsSaved = new Register();
// Initialize the breakpoint Array
breakpointAddresses = new List <string>();
// Initialize the individual Carry Flags
carryADD = false;
carrySUB = false;
carrySHL = false;
carrySHR = false;
}
/// <summary>
/// Executes the next Instruction and increments the Program Counter.
/// </summary>
private CPUExecution ExecuteNextInstruction(out string OutputPortC, out string OutputPortD)
{
bool incrementProgramCounter = true;
OutputPortC = string.Empty;
OutputPortD = string.Empty;
// Check if we are at a breakpoint
if (!breakpointAddresses.Contains(programCounter.GetString()))
{
// Fetch the current instruction from the RAM
instruction.SetBits(ram.ReadValue(programCounter.GetInt()));
switch (instruction.GetOpCode())
{
case OpCode.HLT:
{
// We have finished the end of the program execution
return(CPUExecution.FINISHED);
}
case OpCode.INT:
{
// We have to raise an software based interrupt...
return(CPUExecution.INTERRUPT);
}
case OpCode.SET_A:
{
a = new Register();
// Extract the lower Nibble and store it in A
a.SetBit(3, Helper.IsBitSet(instruction.GetByte(), 3));
a.SetBit(2, Helper.IsBitSet(instruction.GetByte(), 2));
a.SetBit(1, Helper.IsBitSet(instruction.GetByte(), 1));
a.SetBit(0, Helper.IsBitSet(instruction.GetByte(), 0));
break;
}
case OpCode.SET_B:
{
b = new Register();
// Extract the lower Nibble and store it in B
b.SetBit(3, Helper.IsBitSet(instruction.GetByte(), 3));
b.SetBit(2, Helper.IsBitSet(instruction.GetByte(), 2));
b.SetBit(1, Helper.IsBitSet(instruction.GetByte(), 1));
b.SetBit(0, Helper.IsBitSet(instruction.GetByte(), 0));
break;
}
case OpCode.MOV8:
{
c = new Register();
// Upper Nibble
c.SetBit(7, b.Value[3]);
c.SetBit(6, b.Value[2]);
c.SetBit(5, b.Value[1]);
c.SetBit(4, b.Value[0]);
// Lower Nibble
c.SetBit(3, a.Value[3]);
c.SetBit(2, a.Value[2]);
c.SetBit(1, a.Value[1]);
c.SetBit(0, a.Value[0]);
// Calculate Flags
SetFlags();
break;
}
case OpCode.AND:
{
c = new Register();
// Upper Nibble
c.SetBit(7, a.Value[7] & b.Value[7]);
c.SetBit(6, a.Value[6] & b.Value[6]);
c.SetBit(5, a.Value[5] & b.Value[5]);
c.SetBit(4, a.Value[4] & b.Value[4]);
// Lower Nibble
c.SetBit(3, a.Value[3] & b.Value[3]);
c.SetBit(2, a.Value[2] & b.Value[2]);
c.SetBit(1, a.Value[1] & b.Value[1]);
c.SetBit(0, a.Value[0] & b.Value[0]);
// Calculate Flags
SetFlags();
break;
}
case OpCode.OR:
{
c = new Register();
// Upper Nibble
c.SetBit(7, a.Value[7] | b.Value[7]);
c.SetBit(6, a.Value[6] | b.Value[6]);
c.SetBit(5, a.Value[5] | b.Value[5]);
c.SetBit(4, a.Value[4] | b.Value[4]);
// Lower Nibble
c.SetBit(3, a.Value[3] | b.Value[3]);
c.SetBit(2, a.Value[2] | b.Value[2]);
c.SetBit(1, a.Value[1] | b.Value[1]);
c.SetBit(0, a.Value[0] | b.Value[0]);
// Calculate Flags
SetFlags();
break;
}
case OpCode.XOR:
{
c = new Register();
// Upper Nibble
c.SetBit(7, a.Value[7] ^ b.Value[7]);
c.SetBit(6, a.Value[6] ^ b.Value[6]);
c.SetBit(5, a.Value[5] ^ b.Value[5]);
c.SetBit(4, a.Value[4] ^ b.Value[4]);
// Lower Nibble
c.SetBit(3, a.Value[3] ^ b.Value[3]);
c.SetBit(2, a.Value[2] ^ b.Value[2]);
c.SetBit(1, a.Value[1] ^ b.Value[1]);
c.SetBit(0, a.Value[0] ^ b.Value[0]);
// Calculate Flags
SetFlags();
break;
}
case OpCode.SHL:
{
c = new Register();
c.SetBit(7, a.Value[6]);
c.SetBit(6, a.Value[5]);
c.SetBit(5, a.Value[4]);
c.SetBit(4, a.Value[3]);
c.SetBit(3, a.Value[2]);
c.SetBit(2, a.Value[1]);
c.SetBit(1, a.Value[0]);
c.SetBit(0, false);
carrySHL = a.Value.Get(7);
// Calculate Flags
SetFlags();
break;
}
case OpCode.SHR:
{
c = new Register();
c.SetBit(7, false);
c.SetBit(6, a.Value[7]);
c.SetBit(5, a.Value[6]);
c.SetBit(4, a.Value[5]);
c.SetBit(3, a.Value[4]);
c.SetBit(2, a.Value[3]);
c.SetBit(1, a.Value[2]);
c.SetBit(0, a.Value[1]);
carrySHR = a.Value.Get(0);
// Calculate Flags
SetFlags();
break;
}
case OpCode.ADD:
{
c = new Register();
int result = a.GetInt() + b.GetInt();
byte byteResult = (byte)result;
c.SetBit(7, Helper.IsBitSet(byteResult, 7));
c.SetBit(6, Helper.IsBitSet(byteResult, 6));
c.SetBit(5, Helper.IsBitSet(byteResult, 5));
c.SetBit(4, Helper.IsBitSet(byteResult, 4));
c.SetBit(3, Helper.IsBitSet(byteResult, 3));
c.SetBit(2, Helper.IsBitSet(byteResult, 2));
c.SetBit(1, Helper.IsBitSet(byteResult, 1));
c.SetBit(0, Helper.IsBitSet(byteResult, 0));
if (result > 256)
{
carryADD = true;
}
// Calculate Flags
SetFlags();
break;
}
case OpCode.SUB:
{
c = new Register();
int result = a.GetInt() - b.GetInt();
byte byteResult = (byte)result;
c.SetBit(7, Helper.IsBitSet(byteResult, 7));
c.SetBit(6, Helper.IsBitSet(byteResult, 6));
c.SetBit(5, Helper.IsBitSet(byteResult, 5));
c.SetBit(4, Helper.IsBitSet(byteResult, 4));
c.SetBit(3, Helper.IsBitSet(byteResult, 3));
c.SetBit(2, Helper.IsBitSet(byteResult, 2));
c.SetBit(1, Helper.IsBitSet(byteResult, 1));
c.SetBit(0, Helper.IsBitSet(byteResult, 0));
if (result < 0)
{
carrySUB = true;
}
// Calculate Flags
SetFlags();
break;
}
case OpCode.NOT:
{
c = new Register();
c.SetBit(7, !a.Value[7]);
c.SetBit(6, !a.Value[6]);
c.SetBit(5, !a.Value[5]);
c.SetBit(4, !a.Value[4]);
c.SetBit(3, !a.Value[3]);
c.SetBit(2, !a.Value[2]);
c.SetBit(1, !a.Value[1]);
c.SetBit(0, !a.Value[0]);
// Calculate Flags
SetFlags();
break;
}
case OpCode.MOV_ALU_IN_A_D:
{
a = d;
break;
}
case OpCode.MOV_ALU_IN_A_E:
{
a = e;
break;
}
case OpCode.MOV_ALU_IN_A_F:
{
a = f;
break;
}
case OpCode.MOV_ALU_IN_A_G:
{
a = g;
break;
}
case OpCode.MOV_ALU_IN_A_H:
{
a = h;
break;
}
case OpCode.MOV_ALU_IN_A_XL:
{
a = xl;
break;
}
case OpCode.MOV_ALU_IN_A_XH:
{
a = xh;
break;
}
case OpCode.MOV_ALU_IN_B_D:
{
b = d;
break;
}
case OpCode.MOV_ALU_IN_B_E:
{
b = e;
break;
}
case OpCode.MOV_ALU_IN_B_F:
{
b = f;
break;
}
case OpCode.MOV_ALU_IN_B_G:
{
b = g;
break;
}
case OpCode.MOV_ALU_IN_B_H:
{
b = h;
break;
}
case OpCode.MOV_ALU_IN_B_XL:
{
b = xl;
break;
}
case OpCode.MOV_ALU_IN_B_XH:
{
b = xh;
break;
}
case OpCode.MOV_ALU_OUT_D:
{
d = c;
break;
}
case OpCode.MOV_ALU_OUT_E:
{
e = c;
break;
}
case OpCode.MOV_ALU_OUT_F:
{
f = c;
break;
}
case OpCode.MOV_ALU_OUT_G:
{
g = c;
break;
}
case OpCode.MOV_ALU_OUT_H:
{
h = c;
break;
}
case OpCode.MOV_ALU_OUT_XL:
{
xl = c;
break;
}
case OpCode.MOV_ALU_OUT_XH:
{
xh = c;
break;
}
case OpCode.MOV_D_TO_E:
{
e = d;
break;
}
case OpCode.MOV_D_TO_F:
{
f = d;
break;
}
case OpCode.MOV_D_TO_G:
{
g = d;
break;
}
case OpCode.MOV_D_TO_H:
{
h = d;
break;
}
case OpCode.MOV_D_TO_XL:
{
xl = d;
break;
}
case OpCode.MOV_D_TO_XH:
{
xh = d;
break;
}
case OpCode.MOV_E_TO_D:
{
d = e;
break;
}
case OpCode.MOV_E_TO_F:
{
f = e;
break;
}
case OpCode.MOV_E_TO_G:
{
g = e;
break;
}
case OpCode.MOV_E_TO_H:
{
h = e;
break;
}
case OpCode.MOV_E_TO_XL:
{
xl = e;
break;
}
case OpCode.MOV_E_TO_XH:
{
xh = e;
break;
}
case OpCode.MOV_F_TO_D:
{
d = f;
break;
}
case OpCode.MOV_F_TO_E:
{
e = f;
break;
}
case OpCode.MOV_F_TO_G:
{
g = f;
break;
}
case OpCode.MOV_F_TO_H:
{
h = f;
break;
}
case OpCode.MOV_F_TO_XL:
{
xl = f;
break;
}
case OpCode.MOV_G_TO_D:
{
d = g;
break;
}
case OpCode.MOV_G_TO_E:
{
e = g;
break;
}
case OpCode.MOV_G_TO_F:
{
f = g;
break;
}
case OpCode.MOV_G_TO_H:
{
h = g;
break;
}
case OpCode.MOV_G_TO_XL:
{
xl = g;
break;
}
case OpCode.MOV_G_TO_XH:
{
xh = g;
break;
}
case OpCode.MOV_H_TO_D:
{
d = h;
break;
}
case OpCode.MOV_H_TO_E:
{
e = h;
break;
}
case OpCode.MOV_H_TO_F:
{
f = h;
break;
}
case OpCode.MOV_H_TO_G:
{
g = h;
break;
}
case OpCode.MOV_H_TO_XL:
{
xl = h;
break;
}
case OpCode.MOV_H_TO_XH:
{
xh = h;
break;
}
case OpCode.MOV_XL_TO_D:
{
d = xl;
break;
}
case OpCode.MOV_XL_TO_E:
{
e = xl;
break;
}
case OpCode.MOV_XL_TO_F:
{
f = xl;
break;
}
case OpCode.MOV_XL_TO_G:
{
g = xl;
break;
}
case OpCode.MOV_XL_TO_H:
{
h = xl;
break;
}
case OpCode.MOV_XL_TO_XH:
{
xh = xl;
break;
}
case OpCode.MOV_XH_TO_D:
{
d = xh;
break;
}
case OpCode.MOV_XH_TO_E:
{
e = xh;
break;
}
case OpCode.MOV_XH_TO_F:
{
f = xh;
break;
}
case OpCode.MOV_XH_TO_G:
{
g = xh;
break;
}
case OpCode.MOV_XH_TO_H:
{
h = xh;
break;
}
case OpCode.MOV_XH_TO_XL:
{
xl = xh;
break;
}
case OpCode.MOV_M_TO_X:
{
X = m;
break;
}
case OpCode.MOV_M_TO_J:
{
j = m;
break;
}
case OpCode.MOV_M_TO_SP:
{
sp = m;
break;
}
case OpCode.MOV_M_TO_BP:
{
bp = m;
break;
}
case OpCode.MOV_M_TO_Y:
{
y = m;
break;
}
case OpCode.MOV_M_TO_Z:
{
z = m;
break;
}
case OpCode.MOV_M_TO_PC:
{
programCounter = m;
break;
}
case OpCode.MOV_X_TO_M:
{
m = X;
break;
}
case OpCode.MOV_X_TO_J:
{
j = X;
break;
}
case OpCode.MOV_X_TO_SP:
{
sp = X;
break;
}
case OpCode.MOV_X_TO_BP:
{
bp = X;
break;
}
case OpCode.MOV_X_TO_Y:
{
y = X;
break;
}
case OpCode.MOV_X_TO_Z:
{
z = X;
break;
}
case OpCode.MOV_J_TO_M:
{
m = j;
break;
}
case OpCode.MOV_J_TO_X:
{
X = j;
break;
}
case OpCode.MOV_J_TO_SP:
{
sp = j;
break;
}
case OpCode.MOV_J_TO_BP:
{
bp = j;
break;
}
case OpCode.MOV_J_TO_Y:
{
y = j;
break;
}
case OpCode.MOV_J_TO_Z:
{
z = j;
break;
}
case OpCode.MOV_SP_TO_M:
{
m = sp;
break;
}
case OpCode.MOV_SP_TO_X:
{
X = sp;
break;
}
case OpCode.MOV_SP_TO_J:
{
j = sp;
break;
}
case OpCode.MOV_SP_TO_BP:
{
bp = sp;
break;
}
case OpCode.MOV_SP_TO_Y:
{
y = sp;
break;
}
case OpCode.MOV_SP_TO_Z:
{
z = sp;
break;
}
case OpCode.MOV_PC_TO_X:
{
X = programCounter;
break;
}
case OpCode.MOV_BP_TO_M:
{
m = bp;
break;
}
case OpCode.MOV_BP_TO_X:
{
X = bp;
break;
}
case OpCode.MOV_BP_TO_J:
{
j = bp;
break;
}
case OpCode.MOV_BP_TO_SP:
{
sp = bp;
break;
}
case OpCode.MOV_BP_TO_Y:
{
y = bp;
break;
}
case OpCode.MOV_BP_TO_Z:
{
z = bp;
break;
}
case OpCode.MOV_Y_TO_M:
{
m = y;
break;
}
case OpCode.MOV_Y_TO_X:
{
X = y;
break;
}
case OpCode.MOV_Y_TO_J:
{
j = y;
break;
}
case OpCode.MOV_Y_TO_SP:
{
sp = y;
break;
}
case OpCode.MOV_Y_TO_BP:
{
bp = y;
break;
}
case OpCode.MOV_Y_TO_Z:
{
z = y;
break;
}
case OpCode.MOV_Z_TO_M:
{
m = z;
break;
}
case OpCode.MOV_Z_TO_X:
{
X = z;
break;
}
case OpCode.MOV_Z_TO_J:
{
j = z;
break;
}
case OpCode.MOV_Z_TO_SP:
{
sp = z;
break;
}
case OpCode.MOV_Z_TO_BP:
{
bp = z;
break;
}
case OpCode.MOV_Z_TO_Y:
{
y = z;
break;
}
case OpCode.MOV_ALU_C_TO_A:
{
a = c;
break;
}
case OpCode.MOV_ALU_C_TO_B:
{
b = c;
break;
}
case OpCode.LOAD_D:
{
d.SetBits(ram.ReadValue(M.GetInt()));
break;
}
case OpCode.LOAD_E:
{
e.SetBits(ram.ReadValue(M.GetInt()));
break;
}
case OpCode.LOAD_F:
{
f.SetBits(ram.ReadValue(M.GetInt()));
break;
}
case OpCode.LOAD_G:
{
g.SetBits(ram.ReadValue(M.GetInt()));
break;
}
case OpCode.LOAD_H:
{
h.SetBits(ram.ReadValue(M.GetInt()));
break;
}
case OpCode.LOAD_XL:
{
xl.SetBits(ram.ReadValue(M.GetInt()));
break;
}
case OpCode.LOAD_XH:
{
xh.SetBits(ram.ReadValue(M.GetInt()));
break;
}
case OpCode.STORE_D:
{
ram.WriteValue(M.GetInt(), d.GetByte());
break;
}
case OpCode.STORE_E:
{
ram.WriteValue(M.GetInt(), e.GetByte());
break;
}
case OpCode.STORE_F:
{
ram.WriteValue(M.GetInt(), f.GetByte());
break;
}
case OpCode.STORE_G:
{
ram.WriteValue(M.GetInt(), g.GetByte());
break;
}
case OpCode.STORE_H:
{
ram.WriteValue(M.GetInt(), h.GetByte());
break;
}
case OpCode.STORE_XL:
{
ram.WriteValue(M.GetInt(), xl.GetByte());
break;
}
case OpCode.STORE_XH:
{
ram.WriteValue(M.GetInt(), xh.GetByte());
break;
}
case OpCode.SAVE_FLAGS:
{
flagsSaved = flags;
break;
}
case OpCode.RESTORE_FLAGS:
{
flags = flagsSaved;
break;
}
case OpCode.JMP:
{
programCounter = j;
incrementProgramCounter = false;
break;
}
case OpCode.JZ:
{
// The Jump is only performed if the Zero Flag is set to 1
if (flags.Value.Get(1))
{
programCounter = j;
incrementProgramCounter = false;
}
else
{
incrementProgramCounter = true;
}
break;
}
case OpCode.JNZ:
{
// The Jump is only performed if the Zero Flag is set to 0
if (!flags.Value.Get(1))
{
programCounter = j;
incrementProgramCounter = false;
}
else
{
incrementProgramCounter = true;
}
break;
}
case OpCode.JNS:
{
// The Jump is only performed if the Sign Flag is set to 0
if (!flags.Value.Get(0))
{
programCounter = j;
incrementProgramCounter = false;
}
else
{
incrementProgramCounter = true;
}
break;
}
case OpCode.ADDER_16BIT:
{
int result = X.GetInt() + J.GetInt();
Register16 temp = new Register16();
temp.SetBits(result);
X = temp;
break;
}
case OpCode.OUT_C:
{
OutputPortC = xl.GetString();
break;
}
case OpCode.OUT_D:
{
OutputPortD = xl.GetString();
break;
}
case OpCode.IN_A:
{
programCounter.Increment();
return(CPUExecution.IN_A);
}
case OpCode.IN_B:
{
programCounter.Increment();
return(CPUExecution.IN_B);
}
}
}
else
{
// We hit a breakpoint!
return(CPUExecution.BREAKPOINT_HIT);
}
// Increment the Program Counter, if necessary
if (incrementProgramCounter)
{
programCounter.Increment();
}
// There are more CPU instructions available for execution...
return(CPUExecution.MORE_INSTRUCTIONS_AVAILABLE);
}