public static EffectiveAddress Indirect( AddressSize addressSize, SegmentRegister? segment, AddressBaseRegister @base, int displacement = 0) => Indirect(addressSize, segment, @base, index: null, scale: 1, displacement: displacement);
public static EffectiveAddress Indirect(
AddressSize addressSize, SegmentRegister? segment,
AddressBaseRegister? @base, GprCode? index = null, byte scale = 1, int displacement = 0)
{
Contract.Requires(scale == 1 || scale == 2 || scale == 4 || scale == 8
|| (scale == 0 && !index.HasValue));
Contract.Requires(@base != AddressBaseRegister.Rip || (addressSize != AddressSize._16 && index.HasValue));
if (addressSize == AddressSize._16)
{
Contract.Requires(!(@base >= AddressBaseRegister.R8));
Contract.Requires(!(index >= GprCode.R8));
Contract.Requires((short)displacement == displacement);
if (@base.HasValue)
{
if (index.HasValue)
{
Contract.Requires(@base == AddressBaseRegister.B || @base == AddressBaseRegister.BP);
Contract.Requires(index.Value == GprCode.SI || index.Value == GprCode.DI);
}
else
{
Contract.Requires(@base == AddressBaseRegister.SI || @base == AddressBaseRegister.DI
|| @base == AddressBaseRegister.BP || @base == AddressBaseRegister.B);
}
}
else
{
Contract.Requires(!index.HasValue);
}
}
else
{
Contract.Requires(index != GprCode.Esp);
}
// Segment defaults to D, or S if we are using a stack-pointing register
if (!segment.HasValue)
{
segment = (@base == AddressBaseRegister.SP || @base == AddressBaseRegister.BP)
? SegmentRegister.SS : SegmentRegister.DS;
}
var flags = BaseFlags(addressSize, segment.Value);
if (@base.HasValue) flags |= (Flags)(((int)@base + 1) << (int)Flags.BaseReg_Shift);
if (index.HasValue)
{
// Swap eax and esp (esp meaning "none")
if (index.Value == GprCode.Eax) flags |= Flags.IndexReg_Eax;
else flags |= (Flags)((int)index.Value << (int)Flags.IndexReg_Shift);
}
if (scale == 2) flags |= Flags.Scale_2x;
else if (scale == 4) flags |= Flags.Scale_4x;
else if (scale == 8) flags |= Flags.Scale_8x;
return new EffectiveAddress(flags, displacement);
}
