53 lines
1.6 KiB
C#
53 lines
1.6 KiB
C#
using ChocolArm64.Instructions;
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namespace ChocolArm64.Decoders
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{
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class OpCodeMemImm64 : OpCodeMem64
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{
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public long Imm { get; protected set; }
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public bool WBack { get; protected set; }
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public bool PostIdx { get; protected set; }
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protected bool Unscaled { get; private set; }
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private enum MemOp
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{
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Unscaled = 0,
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PostIndexed = 1,
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Unprivileged = 2,
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PreIndexed = 3,
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Unsigned
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}
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public OpCodeMemImm64(Inst inst, long position, int opCode) : base(inst, position, opCode)
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{
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Extend64 = ((opCode >> 22) & 3) == 2;
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WBack = ((opCode >> 24) & 1) == 0;
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// The type is not valid for the Unsigned Immediate 12-bits encoding,
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// because the bits 11:10 are used for the larger Immediate offset.
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MemOp type = WBack ? (MemOp)((opCode >> 10) & 3) : MemOp.Unsigned;
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PostIdx = type == MemOp.PostIndexed;
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Unscaled = type == MemOp.Unscaled ||
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type == MemOp.Unprivileged;
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// Unscaled and Unprivileged doesn't write back,
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// but they do use the 9-bits Signed Immediate.
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if (Unscaled)
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{
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WBack = false;
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}
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if (WBack || Unscaled)
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{
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// 9-bits Signed Immediate.
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Imm = (opCode << 11) >> 23;
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}
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else
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{
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// 12-bits Unsigned Immediate.
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Imm = ((opCode >> 10) & 0xfff) << Size;
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}
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}
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}
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} |