private void RTS(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "PC = ReadMemory((ushort)(++S + 0x100));");
w.WriteLine(Spaces + "PC |= (ushort)(ReadMemory((ushort)(++S + 0x100)) << 8);");
w.WriteLine(Spaces + "PC++;");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void AND(OpcodeInfo op, TextWriter w)
{
GetValue8(op, w, "value8");
w.WriteLine(Spaces + "A &= value8;");
w.WriteLine(Spaces + SetNZ("A"));
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void AND(OpcodeInfo op, TextWriter w)
{
GetValue8(op, w, "value8");
w.WriteLine(Spaces + "A &= value8;");
w.WriteLine(Spaces + SetNZ("A"));
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void GetValue8(OpcodeInfo op, TextWriter w, string dest)
{
switch (op.AddressMode)
{
case AddrMode.Immediate:
w.WriteLine(Spaces + dest + " = ReadMemory(PC++);"); break;
case AddrMode.ZeroPage:
w.WriteLine(Spaces + dest + " = ReadMemory(ReadMemory(PC++));"); break;
case AddrMode.ZeroPageX:
w.WriteLine(Spaces + dest + " = ReadMemory((byte)(ReadMemory(PC++)+X));"); break;
case AddrMode.ZeroPageY:
w.WriteLine(Spaces + dest + " = ReadMemory((byte)(ReadMemory(PC++)+Y));"); break;
case AddrMode.Absolute:
w.WriteLine(Spaces + dest + " = ReadMemory(ReadWord(PC)); PC += 2;"); break;
case AddrMode.AbsoluteX_P:
w.WriteLine(Spaces + "temp16 = ReadWord(PC);");
w.WriteLine(Spaces + dest + " = ReadMemory((ushort)(temp16+X));");
w.WriteLine(Spaces + "if ((temp16 & 0xFF00) != ((temp16 + X) & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.AbsoluteX:
w.WriteLine(Spaces + dest + " = ReadMemory((ushort)(ReadWord(PC)+X));");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.AbsoluteY_P:
w.WriteLine(Spaces + "temp16 = ReadWord(PC);");
w.WriteLine(Spaces + dest + " = ReadMemory((ushort)(temp16+Y));");
w.WriteLine(Spaces + "if ((temp16 & 0xFF00) != ((temp16 + Y) & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.AbsoluteY:
w.WriteLine(Spaces + dest + " = ReadMemory((ushort)(ReadWord(PC)+Y));");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.IndirectX:
w.WriteLine(Spaces + dest + " = ReadMemory(ReadWordPageWrap((byte)(ReadMemory(PC++)+X)));"); break;
case AddrMode.IndirectY:
w.WriteLine(Spaces + dest + " = ReadMemory(ReadWordPageWrap((byte)(ReadMemory(PC++)+Y)));"); break;
case AddrMode.IndirectY_P:
w.WriteLine(Spaces + "temp16 = ReadWordPageWrap(ReadMemory(PC++));");
w.WriteLine(Spaces + dest + " = ReadMemory((ushort)(temp16+Y));");
w.WriteLine(Spaces + "if ((temp16 & 0xFF00) != ((temp16+Y) & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
break;
}
}
private void CMP_reg(OpcodeInfo op, TextWriter w, string reg)
{
GetValue8(op, w, "value8");
w.WriteLine(Spaces + "value16 = (ushort) (" + reg + " - value8);");
w.WriteLine(Spaces + "FlagC = (" + reg + " >= value8);");
w.WriteLine(Spaces + SetNZ("(byte)value16"));
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void JSR(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "temp16 = (ushort)(PC+1);");
w.WriteLine(Spaces + "WriteMemory((ushort)(S-- + 0x100), (byte)(temp16 >> 8));");
w.WriteLine(Spaces + "WriteMemory((ushort)(S-- + 0x100), (byte)temp16);");
w.WriteLine(Spaces + "PC = ReadWord(PC);");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void INC(OpcodeInfo op, TextWriter w)
{
GetAddress(op, w, "value16");
w.WriteLine(Spaces + "value8 = (byte)(ReadMemory(value16) + 1);");
w.WriteLine(Spaces + "WriteMemory(value16, value8);");
w.WriteLine(Spaces + SetNZ("value8"));
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void BIT(OpcodeInfo op, TextWriter w)
{
GetValue8(op, w, "value8");
w.WriteLine(Spaces + "FlagN = (value8 & 0x80) != 0;");
w.WriteLine(Spaces + "FlagV = (value8 & 0x40) != 0;");
w.WriteLine(Spaces + "FlagZ = (A & value8) == 0;");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void RTI(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "P = ReadMemory((ushort)(++S + 0x100));");
w.WriteLine("FlagT = true;// this seems wrong");//this seems wrong
w.WriteLine(Spaces + "PC = ReadMemory((ushort)(++S + 0x100));");
w.WriteLine(Spaces + "PC |= (ushort)(ReadMemory((ushort)(++S + 0x100)) << 8);");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void BIT(OpcodeInfo op, TextWriter w)
{
GetValue8(op, w, "value8");
w.WriteLine(Spaces + "FlagN = (value8 & 0x80) != 0;");
w.WriteLine(Spaces + "FlagV = (value8 & 0x40) != 0;");
w.WriteLine(Spaces + "FlagZ = (A & value8) == 0;");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void SBC(OpcodeInfo op, TextWriter w)
{
GetValue8(op, w, "value8");
w.WriteLine(Spaces + "temp = A - value8 - (FlagC?0:1);");
w.WriteLine(Spaces + "FlagV = ((A ^ value8) & (A ^ temp) & 0x80) != 0;");
w.WriteLine(Spaces + "FlagC = temp >= 0;");
w.WriteLine(Spaces + "A = (byte)temp;");
w.WriteLine(Spaces + SetNZ("A"));
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void JMP(OpcodeInfo op, TextWriter w)
{
switch (op.AddressMode)
{
case AddrMode.Absolute: w.WriteLine(Spaces + "PC = ReadWord(PC);"); break;
case AddrMode.Indirect: w.WriteLine(Spaces + "PC = ReadWordPageWrap(ReadWord(PC));"); break;
}
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void ADC(OpcodeInfo op, TextWriter w)
{
GetValue8(op, w, "value8");
w.WriteLine(Spaces + "temp = value8 + A + (FlagC ? 1 : 0);");
w.WriteLine(Spaces + "FlagV = (~(A ^ value8) & (A ^ temp) & 0x80) != 0;");
w.WriteLine(Spaces + "FlagC = temp > 0xFF;");
w.WriteLine(Spaces + "A = (byte)temp;");
w.WriteLine(Spaces + SetNZ("A"));
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void Branch(OpcodeInfo op, TextWriter w, string flag, bool cond)
{
GetAddress(op, w, "value16");
w.WriteLine(Spaces + "if (Flag" + flag + " == " + cond.ToString().ToLower() + ") {");
w.WriteLine(Spaces + " PendingCycles--; TotalExecutedCycles++;");
w.WriteLine(Spaces + " if ((PC & 0xFF00) != (value16 & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
w.WriteLine(Spaces + " PC = value16;");
w.WriteLine(Spaces + "}");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void NOP(OpcodeInfo op, TextWriter w)
{
// This code is quite insufficient, but at least, we have to increment program counter appropriately.
// For immediate addressing mode, it will be correct, and it will fix desyncs of "Puzznic (J)" and "Puzznic (U)".
// For other addressing modes, I don't know whether they access memory, so further investigation will be needed.
if (op.Size > 1)
{
w.WriteLine(Spaces + "PC += {0};", op.Size - 1);
}
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void Branch(OpcodeInfo op, TextWriter w, string flag, bool cond)
{
GetAddress(op, w, "value16");
w.WriteLine(Spaces + "if (Flag"+flag+" == "+cond.ToString().ToLower()+") {");
w.WriteLine(Spaces + " PendingCycles--; TotalExecutedCycles++;");
w.WriteLine(Spaces + " if ((PC & 0xFF00) != (value16 & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
w.WriteLine(Spaces + " PC = value16;");
w.WriteLine(Spaces + "}");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void Set(byte value, string instr, AddrMode addressMode, int cycles)
{
var op = new OpcodeInfo();
op.Instruction = instr;
op.AddressMode = addressMode;
op.Cycles = cycles;
if (Opcodes[value] != null)
{
throw new Exception("opcode " + value + " already assigned");
}
Opcodes[value] = op;
}
private void PLP(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "//handle I flag differently. sort of a sloppy way to do the job, but it does finish it off.");
w.WriteLine(Spaces + "value8 = ReadMemory((ushort)(++S + 0x100));");
w.WriteLine(Spaces + "if ((value8 & 0x04) != 0 && !FlagI)");
w.WriteLine(Spaces + "\tSEI_Pending = true;");
w.WriteLine(Spaces + "if ((value8 & 0x04) == 0 && FlagI)");
w.WriteLine(Spaces + "\tCLI_Pending = true;");
w.WriteLine(Spaces + "value8 &= unchecked((byte)~0x04);");
w.WriteLine(Spaces + "P &= 0x04;");
w.WriteLine(Spaces + "P |= value8;");
w.WriteLine("FlagT = true;//this seems wrong");//this seems wrong
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void ASL(OpcodeInfo op, TextWriter w)
{
if (op.AddressMode == AddrMode.Accumulator)
{
w.WriteLine(Spaces + "FlagC = (A & 0x80) != 0;");
w.WriteLine(Spaces + "A = (byte) (A << 1);");
w.WriteLine(Spaces + SetNZ("A"));
} else {
GetAddress(op, w, "value16");
w.WriteLine(Spaces + "value8 = ReadMemory(value16);");
w.WriteLine(Spaces + "FlagC = (value8 & 0x80) != 0;");
w.WriteLine(Spaces + "value8 = (byte)(value8 << 1);");
w.WriteLine(Spaces + "WriteMemory(value16, value8);");
w.WriteLine(Spaces + SetNZ("value8"));
}
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void ASL(OpcodeInfo op, TextWriter w)
{
if (op.AddressMode == AddrMode.Accumulator)
{
w.WriteLine(Spaces + "FlagC = (A & 0x80) != 0;");
w.WriteLine(Spaces + "A = (byte) (A << 1);");
w.WriteLine(Spaces + SetNZ("A"));
}
else
{
GetAddress(op, w, "value16");
w.WriteLine(Spaces + "value8 = ReadMemory(value16);");
w.WriteLine(Spaces + "FlagC = (value8 & 0x80) != 0;");
w.WriteLine(Spaces + "value8 = (byte)(value8 << 1);");
w.WriteLine(Spaces + "WriteMemory(value16, value8);");
w.WriteLine(Spaces + SetNZ("value8"));
}
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void ROR(OpcodeInfo op, TextWriter w)
{
if (op.AddressMode == AddrMode.Accumulator)
{
w.WriteLine(Spaces + "temp8 = A;");
w.WriteLine(Spaces + "A = (byte)((A >> 1) | ((P & 1)<<7));");
w.WriteLine(Spaces + "FlagC = (temp8 & 1) != 0;");
w.WriteLine(Spaces + SetNZ("A"));
}
else
{
GetAddress(op, w, "value16");
w.WriteLine(Spaces + "value8 = temp8 = ReadMemory(value16);");
w.WriteLine(Spaces + "value8 = (byte)((value8 >> 1) | ((P & 1)<<7));");
w.WriteLine(Spaces + "WriteMemory(value16, value8);");
w.WriteLine(Spaces + "FlagC = (temp8 & 1) != 0;");
w.WriteLine(Spaces + SetNZ("value8"));
}
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void GetAddress(OpcodeInfo op, TextWriter w, string dest)
{
// TODO it APPEARS that the +1 opcode penalty applies to all AbsoluteX, AbsoluteY, and IndirectY
// but this is not completely clear. the doc has some exceptions, but are they real?
switch (op.AddressMode)
{
case AddrMode.ZeroPage:
w.WriteLine(Spaces + dest + " = ReadMemory(PC++);"); break;
case AddrMode.ZeroPageX:
w.WriteLine(Spaces + dest + " = (byte)(ReadMemory(PC++)+X);"); break;
case AddrMode.ZeroPageY:
w.WriteLine(Spaces + dest + " = (byte)(ReadMemory(PC++)+Y);"); break;
case AddrMode.Absolute:
w.WriteLine(Spaces + dest + " = ReadWord(PC); PC += 2;"); break;
case AddrMode.AbsoluteX:
w.WriteLine(Spaces + dest + " = (ushort)(ReadWord(PC)+X);");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.AbsoluteX_P:
w.WriteLine(Spaces + "temp16 = ReadWord(PC);");
w.WriteLine(Spaces + dest + " = (ushort)(temp16+X);");
w.WriteLine(Spaces + "if ((temp16 & 0xFF00) != ((temp16 + X) & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.AbsoluteY:
w.WriteLine(Spaces + dest + " = (ushort)(ReadWord(PC)+Y);");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.AbsoluteY_P:
w.WriteLine(Spaces + "temp16 = ReadWord(PC);");
w.WriteLine(Spaces + dest + " = (ushort)(temp16+Y);");
w.WriteLine(Spaces + "if ((temp16 & 0xFF00) != ((temp16 + Y) & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.IndirectX:
w.WriteLine(Spaces + "temp8 = (byte)(ReadMemory(PC++) + X);");
w.WriteLine(Spaces + dest + " = ReadWordPageWrap(temp8);");
break;
case AddrMode.IndirectY:
w.WriteLine(Spaces + "temp16 = ReadWordPageWrap(ReadMemory(PC++));");
w.WriteLine(Spaces + dest + " = (ushort)(temp16+Y);");
break;
case AddrMode.IndirectY_P:
w.WriteLine(Spaces + "temp16 = ReadWordPageWrap(ReadMemory(PC++));");
w.WriteLine(Spaces + dest + " = (ushort)(temp16+Y);");
w.WriteLine(Spaces + "if ((temp16 & 0xFF00) != ((temp16+Y) & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
break;
case AddrMode.Relative:
w.WriteLine(Spaces + "rel8 = (sbyte)ReadMemory(PC++);");
w.WriteLine(Spaces + dest + " = (ushort)(PC+rel8);");
break;
}
}
private void TYA(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "A = Y;");
w.WriteLine(Spaces + SetNZ("A"));
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void STY(OpcodeInfo op, TextWriter w)
{
GetAddress(op, w, "value16");
w.WriteLine(Spaces + "WriteMemory(value16, Y);");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void ROR(OpcodeInfo op, TextWriter w)
{
if (op.AddressMode == AddrMode.Accumulator)
{
w.WriteLine(Spaces + "temp8 = A;");
w.WriteLine(Spaces + "A = (byte)((A >> 1) | ((P & 1)<<7));");
w.WriteLine(Spaces + "FlagC = (temp8 & 1) != 0;");
w.WriteLine(Spaces + SetNZ("A"));
}
else
{
GetAddress(op, w, "value16");
w.WriteLine(Spaces + "value8 = temp8 = ReadMemory(value16);");
w.WriteLine(Spaces + "value8 = (byte)((value8 >> 1) | ((P & 1)<<7));");
w.WriteLine(Spaces + "WriteMemory(value16, value8);");
w.WriteLine(Spaces + "FlagC = (temp8 & 1) != 0;");
w.WriteLine(Spaces + SetNZ("value8"));
}
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void PLA(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "A = ReadMemory((ushort)(++S + 0x100));");
w.WriteLine(Spaces + SetNZ("A"));
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void PHA(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "WriteMemory((ushort)(S-- + 0x100), A);");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void CLV(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "FlagV = false;");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void PLA(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "A = ReadMemory((ushort)(++S + 0x100));");
w.WriteLine(Spaces + SetNZ("A"));
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void TYA(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "A = Y;");
w.WriteLine(Spaces + SetNZ("A"));
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void TXS(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "S = X;");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void STY(OpcodeInfo op, TextWriter w)
{
GetAddress(op, w, "value16");
w.WriteLine(Spaces + "WriteMemory(value16, Y);");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void GetValue8(OpcodeInfo op, TextWriter w, string dest)
{
switch (op.AddressMode)
{
case AddrMode.Immediate:
w.WriteLine(Spaces + dest + " = ReadMemory(PC++);"); break;
case AddrMode.ZeroPage:
w.WriteLine(Spaces + dest + " = ReadMemory(ReadMemory(PC++));"); break;
case AddrMode.ZeroPageX:
w.WriteLine(Spaces + dest + " = ReadMemory((byte)(ReadMemory(PC++)+X));"); break;
case AddrMode.ZeroPageY:
w.WriteLine(Spaces + dest + " = ReadMemory((byte)(ReadMemory(PC++)+Y));"); break;
case AddrMode.Absolute:
w.WriteLine(Spaces + dest + " = ReadMemory(ReadWord(PC)); PC += 2;"); break;
case AddrMode.AbsoluteX_P:
w.WriteLine(Spaces + "temp16 = ReadWord(PC);");
w.WriteLine(Spaces + dest + " = ReadMemory((ushort)(temp16+X));");
w.WriteLine(Spaces + "if ((temp16 & 0xFF00) != ((temp16 + X) & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.AbsoluteX:
w.WriteLine(Spaces + dest + " = ReadMemory((ushort)(ReadWord(PC)+X));");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.AbsoluteY_P:
w.WriteLine(Spaces + "temp16 = ReadWord(PC);");
w.WriteLine(Spaces + dest + " = ReadMemory((ushort)(temp16+Y));");
w.WriteLine(Spaces + "if ((temp16 & 0xFF00) != ((temp16 + Y) & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.AbsoluteY:
w.WriteLine(Spaces + dest + " = ReadMemory((ushort)(ReadWord(PC)+Y));");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.IndirectX:
w.WriteLine(Spaces + dest + " = ReadMemory(ReadWordPageWrap((byte)(ReadMemory(PC++)+X)));"); break;
case AddrMode.IndirectY:
w.WriteLine(Spaces + dest + " = ReadMemory(ReadWordPageWrap((byte)(ReadMemory(PC++)+Y)));"); break;
case AddrMode.IndirectY_P:
w.WriteLine(Spaces + "temp16 = ReadWordPageWrap(ReadMemory(PC++));");
w.WriteLine(Spaces + dest + " = ReadMemory((ushort)(temp16+Y));");
w.WriteLine(Spaces + "if ((temp16 & 0xFF00) != ((temp16+Y) & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
break;
}
}
private void PHP(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "FlagB = true; //why would it do this?? how weird");
w.WriteLine(Spaces + "WriteMemory((ushort)(S-- + 0x100), P);");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void PHP(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "FlagB = true; //why would it do this?? how weird");
w.WriteLine(Spaces + "WriteMemory((ushort)(S-- + 0x100), P);");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void CLV(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "FlagV = false;");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void PLP(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "//handle I flag differently. sort of a sloppy way to do the job, but it does finish it off.");
w.WriteLine(Spaces + "value8 = ReadMemory((ushort)(++S + 0x100));");
w.WriteLine(Spaces + "if ((value8 & 0x04) != 0 && !FlagI)");
w.WriteLine(Spaces + "\tSEI_Pending = true;");
w.WriteLine(Spaces + "if ((value8 & 0x04) == 0 && FlagI)");
w.WriteLine(Spaces + "\tCLI_Pending = true;");
w.WriteLine(Spaces + "value8 &= unchecked((byte)~0x04);");
w.WriteLine(Spaces + "P &= 0x04;");
w.WriteLine(Spaces + "P |= value8;");
w.WriteLine("FlagT = true;//this seems wrong");//this seems wrong
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void PHA(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "WriteMemory((ushort)(S-- + 0x100), A);");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void RTI(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "P = ReadMemory((ushort)(++S + 0x100));");
w.WriteLine("FlagT = true;// this seems wrong");//this seems wrong
w.WriteLine(Spaces + "PC = ReadMemory((ushort)(++S + 0x100));");
w.WriteLine(Spaces + "PC |= (ushort)(ReadMemory((ushort)(++S + 0x100)) << 8);");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void GetAddress(OpcodeInfo op, TextWriter w, string dest)
{
// TODO it APPEARS that the +1 opcode penalty applies to all AbsoluteX, AbsoluteY, and IndirectY
// but this is not completely clear. the doc has some exceptions, but are they real?
switch (op.AddressMode)
{
case AddrMode.ZeroPage:
w.WriteLine(Spaces + dest + " = ReadMemory(PC++);"); break;
case AddrMode.ZeroPageX:
w.WriteLine(Spaces + dest + " = (byte)(ReadMemory(PC++)+X);"); break;
case AddrMode.ZeroPageY:
w.WriteLine(Spaces + dest + " = (byte)(ReadMemory(PC++)+Y);"); break;
case AddrMode.Absolute:
w.WriteLine(Spaces + dest + " = ReadWord(PC); PC += 2;"); break;
case AddrMode.AbsoluteX:
w.WriteLine(Spaces + dest + " = (ushort)(ReadWord(PC)+X);");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.AbsoluteX_P:
w.WriteLine(Spaces + "temp16 = ReadWord(PC);");
w.WriteLine(Spaces + dest + " = (ushort)(temp16+X);");
w.WriteLine(Spaces + "if ((temp16 & 0xFF00) != ((temp16 + X) & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.AbsoluteY:
w.WriteLine(Spaces + dest + " = (ushort)(ReadWord(PC)+Y);");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.AbsoluteY_P:
w.WriteLine(Spaces + "temp16 = ReadWord(PC);");
w.WriteLine(Spaces + dest + " = (ushort)(temp16+Y);");
w.WriteLine(Spaces + "if ((temp16 & 0xFF00) != ((temp16 + Y) & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
w.WriteLine(Spaces + "PC += 2;");
break;
case AddrMode.IndirectX:
w.WriteLine(Spaces + "temp8 = (byte)(ReadMemory(PC++) + X);");
w.WriteLine(Spaces + dest + " = ReadWordPageWrap(temp8);");
break;
case AddrMode.IndirectY:
w.WriteLine(Spaces + "temp16 = ReadWordPageWrap(ReadMemory(PC++));");
w.WriteLine(Spaces + dest + " = (ushort)(temp16+Y);");
break;
case AddrMode.IndirectY_P:
w.WriteLine(Spaces + "temp16 = ReadWordPageWrap(ReadMemory(PC++));");
w.WriteLine(Spaces + dest + " = (ushort)(temp16+Y);");
w.WriteLine(Spaces + "if ((temp16 & 0xFF00) != ((temp16+Y) & 0xFF00)) ");
w.WriteLine(Spaces + " { PendingCycles--; TotalExecutedCycles++; }");
break;
case AddrMode.Relative:
w.WriteLine(Spaces + "rel8 = (sbyte)ReadMemory(PC++);");
w.WriteLine(Spaces + dest +" = (ushort)(PC+rel8);");
break;
}
}
private void RTS(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "PC = ReadMemory((ushort)(++S + 0x100));");
w.WriteLine(Spaces + "PC |= (ushort)(ReadMemory((ushort)(++S + 0x100)) << 8);");
w.WriteLine(Spaces + "PC++;");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void INC(OpcodeInfo op, TextWriter w)
{
GetAddress(op, w, "value16");
w.WriteLine(Spaces + "value8 = (byte)(ReadMemory(value16) + 1);");
w.WriteLine(Spaces + "WriteMemory(value16, value8);");
w.WriteLine(Spaces + SetNZ("value8"));
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void TXS(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "S = X;");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void JMP(OpcodeInfo op, TextWriter w)
{
switch (op.AddressMode)
{
case AddrMode.Absolute: w.WriteLine(Spaces+"PC = ReadWord(PC);"); break;
case AddrMode.Indirect: w.WriteLine(Spaces+"PC = ReadWordPageWrap(ReadWord(PC));"); break;
}
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void Set(byte value, string instr, AddrMode addressMode, int cycles)
{
var op = new OpcodeInfo();
op.Instruction = instr;
op.AddressMode = addressMode;
op.Cycles = cycles;
if (Opcodes[value] != null)
throw new Exception("opcode "+value+" already assigned");
Opcodes[value] = op;
}
private void JSR(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "temp16 = (ushort)(PC+1);");
w.WriteLine(Spaces + "WriteMemory((ushort)(S-- + 0x100), (byte)(temp16 >> 8));");
w.WriteLine(Spaces + "WriteMemory((ushort)(S-- + 0x100), (byte)temp16);");
w.WriteLine(Spaces + "PC = ReadWord(PC);");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void CLI(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "//FlagI = false;");
w.WriteLine(Spaces + "CLI_Pending = true;");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void NOP(OpcodeInfo op, TextWriter w)
{
// This code is quite insufficient, but at least, we have to increment program counter appropriately.
// For immediate addressing mode, it will be correct, and it will fix desyncs of "Puzznic (J)" and "Puzznic (U)".
// For other addressing modes, I don't know whether they access memory, so further investigation will be needed.
if (op.Size > 1)
w.WriteLine(Spaces+"PC += {0};", op.Size-1);
w.WriteLine(Spaces+"PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void CMP_reg(OpcodeInfo op, TextWriter w, string reg)
{
GetValue8(op, w, "value8");
w.WriteLine(Spaces + "value16 = (ushort) (" + reg + " - value8);");
w.WriteLine(Spaces + "FlagC = (" + reg + " >= value8);");
w.WriteLine(Spaces + SetNZ("(byte)value16"));
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
private void CLI(OpcodeInfo op, TextWriter w)
{
w.WriteLine(Spaces + "//FlagI = false;");
w.WriteLine(Spaces + "CLI_Pending = true;");
w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
}
