public static int LdA16Sp(Opcode op, GbMemory mem)
{
byte low = mem.ReadCycleI8();
byte high = mem.ReadCycleI8();
mem.WriteCycle(new GbUInt16(high, low), mem.R.Sp.LowByte);
mem.WriteCycle((GbUInt16)(new GbUInt16(high, low) + 1), mem.R.Sp.HighByte);
return(5);
}
public static int LdR16(Opcode op, GbMemory mem)
{
if (op.Src == 8)
{
mem.WriteCycle((op.Dest == 2 || op.Dest == 3) ? mem.R.Hl : mem.R.GetR16Sp(op.Dest), mem.R.A);
}
else
{
mem.R.A = mem.ReadCycle((op.Src == 2 || op.Src == 3) ? mem.R.Hl : mem.R.GetR16Sp(op.Src));
}
if (op.Src == 2 || op.Dest == 2)
{
mem.R.Hl++;
}
else if (op.Src == 3 || op.Dest == 3)
{
mem.R.Hl--;
}
else
{
// Do nothing.
}
return(2);
}
public static int LdH(Opcode op, GbMemory mem)
{
if (op.Dest == 7)
{
mem.R.A = mem.ReadCycle(new GbUInt16(0xFF, mem.ReadCycleI8()));
}
else
{
mem.WriteCycle(new GbUInt16(0xFF, mem.ReadCycleI8()), mem.R.A);
}
return(3);
}
public static int LdD8(Opcode op, GbMemory mem)
{
byte val = mem.ReadCycleI8();
if (op.Dest == 6)
{
mem.WriteCycle(mem.R.Hl, val);
return(3);
}
mem.R.SetR8(op.Dest, val);
return(2);
}
public static int LdA16(Opcode op, GbMemory mem)
{
byte low = mem.ReadCycleI8();
byte high = mem.ReadCycleI8();
if (op.Dest == 7)
{
mem.R.A = mem.ReadCycle(new GbUInt16(high, low));
}
else
{
mem.WriteCycle(new GbUInt16(high, low), mem.R.A);
}
return(4);
}
public static int Ld8(Opcode op, GbMemory memory)
{
if (op.Src == 6 || op.Dest == 6)
{
if (op.Src == op.Dest) // By math logic, these are both 6 if this is true.
{
throw new InvalidOperationException("Opcode with dest = 6 and src = 6 is invalid for this instruction.");
}
if (op.Src == 6)
{
memory.R.SetR8(op.Dest, memory.ReadCycleHl());
}
else
{
memory.WriteCycle(memory.R.Hl, memory.R.GetR8(op.Src));
}
return(2);
}
memory.R.SetR8(op.Dest, memory.R.GetR8(op.Src));
return(1);
}