Ryujinx/ChocolArm64/Decoder/AOpCodeMemImm.cs

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2018-02-05 00:08:20 +01:00
using ChocolArm64.Instruction;
namespace ChocolArm64.Decoder
{
class AOpCodeMemImm : AOpCodeMem
{
public long Imm { get; protected set; }
public bool WBack { get; protected set; }
public bool PostIdx { get; protected set; }
protected bool Unscaled { get; private set; }
private enum MemOp
{
Unscaled = 0,
PostIndexed = 1,
Unprivileged = 2,
PreIndexed = 3,
Unsigned
}
public AOpCodeMemImm(AInst Inst, long Position, int OpCode) : base(Inst, Position, OpCode)
{
Extend64 = ((OpCode >> 22) & 3) == 2;
WBack = ((OpCode >> 24) & 1) == 0;
//The type is not valid for the Unsigned Immediate 12-bits encoding,
//because the bits 11:10 are used for the larger Immediate offset.
MemOp Type = WBack ? (MemOp)((OpCode >> 10) & 3) : MemOp.Unsigned;
PostIdx = Type == MemOp.PostIndexed;
Unscaled = Type == MemOp.Unscaled ||
Type == MemOp.Unprivileged;
//Unscaled and Unprivileged doesn't write back,
//but they do use the 9-bits Signed Immediate.
if (Unscaled)
{
WBack = false;
}
if (WBack || Unscaled)
{
//9-bits Signed Immediate.
Imm = (OpCode << 43) >> 55;
}
else
{
//12-bits Unsigned Immediate.
Imm = ((OpCode >> 10) & 0xfff) << Size;
}
}
}
}