public static void Compare(IReadonlyRegister <byte> target, byte operand, IFlags flags)
{
flags.Zero = target.Value == operand;
flags.Subtract = true;
flags.Carry = target.Value < operand;
flags.HalfCarry = (target.Value & 0xF) < (operand & 0xF);
}
// Used for LDHL SP, e and ADD SP, e
public static void LoadWithSignedOffset(IWriteonlyRegister <ushort> target, IReadonlyRegister <ushort> source, sbyte offset, IFlags flags)
{
var old = source.Value;
target.Value = (ushort)(source.Value + offset);
flags.Zero = false;
flags.Subtract = false;
flags.Carry = (old & 0xFF) + (offset & 0xFF) >= 0x100;
flags.HalfCarry = (old & 0xF) + (offset & 0xF) >= 0x10;
}
public static bool GetBit(this IReadonlyRegister <ushort> s, int index) => s.Value.GetBit(index);
// Aliases public static bool GetBit(this IReadonlyRegister <byte> b, int index) => b.Value.GetBit(index);
public static void TestBit(IReadonlyRegister <byte> source, int index, IFlags flags)
{
flags.Zero = !source.GetBit(index);
flags.Subtract = false;
flags.HalfCarry = true;
}