/// <summary>
/// The BIT 7,(IY+n) instruction
/// </summary>
byte BIT_7_aIY_plus_n(byte offset)
{
FetchFinished();
var address = (ushort)(Registers.IY + (SByte)offset);
var oldValue = ProcessorAgent.ReadFromMemory(address);
var bitValue = oldValue.GetBit(7);
Registers.ZF = Registers.PF = ~bitValue;
Registers.SF = bitValue;
Registers.HF = 1;
Registers.NF = 0;
return(20);
}
/// <summary>
/// The POP HL instruction.
/// </summary>
private byte POP_HL()
{
FetchFinished();
var sp = Registers.SP.ToUShort();
var newHL = NumberUtils.CreateShort(
ProcessorAgent.ReadFromMemory(sp),
ProcessorAgent.ReadFromMemory(sp.Inc()));
Registers.HL = newHL;
Registers.SP = Registers.SP.Add(2);
return(10);
}
/// <summary>
/// The RETI instruction.
/// </summary>
private byte RETI()
{
FetchFinished(isRet: true);
var sp = (ushort)Registers.SP;
var newPC = NumberUtils.CreateShort(
ProcessorAgent.ReadFromMemory(sp),
ProcessorAgent.ReadFromMemory((ushort)(sp + 1)));
Registers.PC = (ushort)newPC;
Registers.SP += 2;
return(14);
}
/// <summary>
/// The BIT 7,(HL) instruction
/// </summary>
byte BIT_7_aHL()
{
FetchFinished();
var address = (ushort)Registers.HL;
var oldValue = ProcessorAgent.ReadFromMemory(address);
var bitValue = oldValue.GetBit(7);
Registers.ZF = Registers.PF = ~bitValue;
Registers.SF = bitValue;
Registers.HF = 1;
Registers.NF = 0;
return(12);
}
/// <summary>
/// The POP BC instruction.
/// </summary>
private byte POP_BC()
{
FetchFinished();
var sp = (ushort)Registers.SP;
var newBC = NumberUtils.CreateShort(
ProcessorAgent.ReadFromMemory(sp),
ProcessorAgent.ReadFromMemory((ushort)(sp + 1)));
Registers.BC = newBC;
Registers.SP += 2;
return(10);
}
/// <summary>
/// The BIT 7,(IY+n) instruction
/// </summary>
byte BIT_7_aIY_plus_n(byte offset)
{
FetchFinished();
var address = Registers.IY.ToUShort().Add(offset.ToSignedByte());
var oldValue = ProcessorAgent.ReadFromMemory(address);
var bitValue = oldValue.GetBit(7);
Registers.ZF = Registers.PF = ~bitValue;
Registers.SF = bitValue;
Registers.HF = 1;
Registers.NF = 0;
return(20);
}
/// <summary>
/// The RETN instruction.
/// </summary>
private byte RETN()
{
FetchFinished(isRet: true);
var sp = Registers.SP.ToUShort();
var newPC = NumberUtils.CreateShort(
ProcessorAgent.ReadFromMemory(sp),
ProcessorAgent.ReadFromMemory(sp.Inc()));
Registers.PC = newPC.ToUShort();
Registers.SP = Registers.SP.Add(2);
Registers.IFF1 = Registers.IFF2;
return(14);
}
/// <summary>
/// The DEC (HL) instruction.
/// </summary>
private byte DEC_aHL()
{
FetchFinished();
var address = Registers.HL.ToUShort();
var oldValue = ProcessorAgent.ReadFromMemory(address);
var newValue = oldValue.Dec();
ProcessorAgent.WriteToMemory(address, newValue);
Registers.SF = newValue.GetBit(7);
Registers.ZF = (newValue == 0);
Registers.HF = ((newValue & 0x0F) == 0x0F);
Registers.PF = (newValue == 0x7F);
Registers.NF = 1;
SetFlags3and5From(newValue);
return(11);
}
/// <summary>
/// The INC (HL) instruction.
/// </summary>
private byte INC_aHL()
{
FetchFinished();
var address = (ushort)Registers.HL;
var oldValue = ProcessorAgent.ReadFromMemory(address);
var newValue = (byte)(oldValue + 1);
ProcessorAgent.WriteToMemory(address, newValue);
Registers.SF = newValue.GetBit(7);
Registers.ZF = (newValue == 0);
Registers.HF = ((newValue & 0x0F) == 0x00);
Registers.PF = (newValue == 0x80);
Registers.NF = 0;
SetFlags3and5From(newValue);
return(11);
}
/// <summary>
/// The RET PO instruction.
/// </summary>
private byte RET_PO()
{
FetchFinished(isRet: true);
if (Registers.PF == 1)
{
return(5);
}
var sp = Registers.SP.ToUShort();
var newPC = NumberUtils.CreateShort(
ProcessorAgent.ReadFromMemory(sp),
ProcessorAgent.ReadFromMemory(sp.Inc()));
Registers.PC = newPC.ToUShort();
Registers.SP = Registers.SP.Add(2);
return(11);
}
/// The OR (HL) instruction.
/// </summary>
private byte OR_aHL()
{
FetchFinished();
var oldValue = Registers.A;
var address = (ushort)Registers.HL;
var argument = ProcessorAgent.ReadFromMemory(address);
var newValue = (byte)(oldValue | argument);
Registers.A = newValue;
Registers.SF = newValue.GetBit(7);
Registers.ZF = (newValue == 0);
Registers.HF = 0;
Registers.PF = Parity[newValue];
Registers.NF = 0;
Registers.CF = 0;
SetFlags3and5From(newValue);
return(7);
}
/// <summary>
/// The DEC (IY+n) instruction.
/// </summary>
private byte DEC_aIY_plus_n()
{
var offset = ProcessorAgent.FetchNextOpcode();
FetchFinished();
var address = Registers.IY.ToUShort().Add(offset.ToSignedByte());
var oldValue = ProcessorAgent.ReadFromMemory(address);
var newValue = oldValue.Dec();
ProcessorAgent.WriteToMemory(address, newValue);
Registers.SF = newValue.GetBit(7);
Registers.ZF = (newValue == 0);
Registers.HF = ((newValue & 0x0F) == 0x0F);
Registers.PF = (newValue == 0x7F);
Registers.NF = 1;
SetFlags3and5From(newValue);
return(23);
}
/// <summary>
/// The DEC (IY+n) instruction.
/// </summary>
private byte DEC_aIY_plus_n()
{
var offset = ProcessorAgent.FetchNextOpcode();
FetchFinished();
var address = (ushort)(Registers.IY + (SByte)offset);
var oldValue = ProcessorAgent.ReadFromMemory(address);
var newValue = (byte)(oldValue - 1);
ProcessorAgent.WriteToMemory(address, newValue);
Registers.SF = newValue.GetBit(7);
Registers.ZF = (newValue == 0);
Registers.HF = ((newValue & 0x0F) == 0x0F);
Registers.PF = (newValue == 0x7F);
Registers.NF = 1;
SetFlags3and5From(newValue);
return(23);
}
/// The AND (IY+n) instruction.
/// </summary>
private byte AND_aIY_plus_n()
{
var offset = ProcessorAgent.FetchNextOpcode();
FetchFinished();
var oldValue = Registers.A;
var address = (ushort)(Registers.IY + (SByte)offset);
var argument = ProcessorAgent.ReadFromMemory(address);
var newValue = (byte)(oldValue & argument);
Registers.A = newValue;
Registers.SF = newValue.GetBit(7);
Registers.ZF = (newValue == 0);
Registers.HF = 1;
Registers.PF = Parity[newValue];
Registers.NF = 0;
Registers.CF = 0;
SetFlags3and5From(newValue);
return(19);
}
/// The OR (IX+n) instruction.
/// </summary>
private byte OR_aIX_plus_n()
{
var offset = ProcessorAgent.FetchNextOpcode();
FetchFinished();
var oldValue = Registers.A;
var address = Registers.IX.ToUShort().Add(offset.ToSignedByte());
var argument = ProcessorAgent.ReadFromMemory(address);
var newValue = (byte)(oldValue | argument);
Registers.A = newValue;
Registers.SF = newValue.GetBit(7);
Registers.ZF = (newValue == 0);
Registers.HF = 0;
Registers.PF = Parity[newValue];
Registers.NF = 0;
Registers.CF = 0;
SetFlags3and5From(newValue);
return(19);
}
/// <summary>
/// The OUTD instruction.
/// </summary>
byte OUTD()
{
FetchFinished();
var portNumber = Registers.C;
var address = Registers.HL;
var value = ProcessorAgent.ReadFromMemory(address.ToUShort());
ProcessorAgent.WriteToPort(portNumber, value);
Registers.HL = address.Dec();
var counter = Registers.B;
counter = counter.Dec();
Registers.B = counter;
Registers.ZF = (counter == 0);
Registers.NF = 1;
Registers.SF = counter.GetBit(7);
SetFlags3and5From(counter);
return(16);
}
/// <summary>
/// The OUTI instruction.
/// </summary>
byte OUTI()
{
FetchFinished();
var portNumber = Registers.C;
var address = Registers.HL;
var value = ProcessorAgent.ReadFromMemory((ushort)address);
ProcessorAgent.WriteToPort(portNumber, value);
Registers.HL++;
var counter = Registers.B;
counter = (byte)(counter - 1);
Registers.B = counter;
Registers.ZF = (counter == 0);
Registers.NF = 1;
Registers.SF = counter.GetBit(7);
SetFlags3and5From(counter);
return(16);
}
/// <summary>
/// The RLD instruction.
/// </summary>
byte RLD()
{
FetchFinished();
var memoryAddress = Registers.HL.ToUShort();
var Avalue = Registers.A;
var HLcontents = ProcessorAgent.ReadFromMemory(memoryAddress);
var newAvalue = (byte)((Avalue & 0xF0) | ((HLcontents >> 4) & 0x0F));
var newHLcontents = (byte)(((HLcontents << 4) & 0xF0) | (Avalue & 0x0F));
Registers.A = newAvalue;
ProcessorAgent.WriteToMemory(memoryAddress, newHLcontents);
Registers.SF = newAvalue.GetBit(7);
Registers.ZF = (newAvalue == 0);
Registers.HF = 0;
Registers.PF = Parity[newAvalue];
Registers.NF = 0;
SetFlags3and5From(newAvalue);
return(18);
}