private void Emit(OpcodeMap map, byte opcode8, byte opcode, Gpr reg, EffectiveAddress rm)
{
WritePrefixes(reg, rm);
Emit(map, reg.Size == OperandSize.Byte ? opcode8 : opcode);
var displacementSize = rm.MinimumDisplacementSize;
var encoding = rm.Encode(
context.GetDefaultAddressSize(), reg.Code.GetLow3Bits(), displacementSize);
Write(encoding.ModRM);
if (encoding.Sib.HasValue) Write(encoding.Sib.Value);
switch (displacementSize)
{
case DisplacementSize._8: Write((sbyte)encoding.Displacement); break;
case DisplacementSize._16: Write((short)encoding.Displacement); break;
case DisplacementSize._32: Write(encoding.Displacement); break;
}
}
private void WritePrefixes(Gpr reg, EffectiveAddress effectiveAddress)
{
if (effectiveAddress.RequiresSegmentOverride)
Write(LegacyPrefixEnum.GetSegmentOverride(effectiveAddress.Segment));
var effectiveAddressSize = effectiveAddress.AddressSize;
if (effectiveAddressSize != context.GetDefaultAddressSize())
{
if (effectiveAddressSize != context.GetEffectiveAddressSize(@override: true))
throw new InvalidDataException();
Write(LegacyPrefix.AddressSizeOverride);
}
// Rex
Rex? rex = null;
if (reg.Part == GprPart.Qword)
{
if (context != CodeContext.SixtyFourBit) throw new ArgumentException("reg");
rex = rex.GetValueOrDefault() | Rex.OperandSize64;
}
else if (reg.Size == OperandSize.Byte)
{
// Might require rex for low byte
throw new NotImplementedException();
}
if (reg.Code >= GprCode.R8) rex = rex.GetValueOrDefault() | Rex.ModRegExtension;
if (effectiveAddress.BaseAsGprCode >= GprCode.R8) rex = rex.GetValueOrDefault() | Rex.BaseRegExtension;
if (effectiveAddress.IndexAsGprCode >= GprCode.R8) rex = rex.GetValueOrDefault() | Rex.IndexRegExtension;
if (rex.HasValue) Write(rex.Value);
}
private void Emit(byte opcode8, byte opcode, Gpr reg, EffectiveAddress rm) => Emit(OpcodeMap.Default, opcode8, opcode, reg, rm);
public void Mov(Gpr dest, EffectiveAddress src) => Emit(0x8A, 0x8B, dest, src);
public void Mov(EffectiveAddress dest, Gpr src) => Emit(0x88, 0x89, src, dest);