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107 lines
2.7 KiB
C#
107 lines
2.7 KiB
C#
using System;
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namespace ChocolArm64.Decoder
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{
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static class ADecoderHelper
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{
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public struct BitMask
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{
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public long WMask;
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public long TMask;
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public int Pos;
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public int Shift;
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public bool IsUndefined;
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public static BitMask Invalid => new BitMask { IsUndefined = true };
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}
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public static BitMask DecodeBitMask(int OpCode, bool Immediate)
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{
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int ImmS = (OpCode >> 10) & 0x3f;
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int ImmR = (OpCode >> 16) & 0x3f;
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int N = (OpCode >> 22) & 1;
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int SF = (OpCode >> 31) & 1;
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int Length = ABitUtils.HighestBitSet32((~ImmS & 0x3f) | (N << 6));
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if (Length < 1 || (SF == 0 && N != 0))
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{
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return BitMask.Invalid;
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}
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int Size = 1 << Length;
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int Levels = Size - 1;
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int S = ImmS & Levels;
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int R = ImmR & Levels;
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if (Immediate && S == Levels)
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{
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return BitMask.Invalid;
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}
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long WMask = ABitUtils.FillWithOnes(S + 1);
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long TMask = ABitUtils.FillWithOnes(((S - R) & Levels) + 1);
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if (R > 0)
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{
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WMask = ABitUtils.RotateRight(WMask, R, Size);
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WMask &= ABitUtils.FillWithOnes(Size);
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}
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return new BitMask()
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{
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WMask = ABitUtils.Replicate(WMask, Size),
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TMask = ABitUtils.Replicate(TMask, Size),
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Pos = ImmS,
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Shift = ImmR
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};
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}
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public static long DecodeImm8Float(long Imm, int Size)
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{
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int E = 0, F = 0;
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switch (Size)
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{
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case 0: E = 8; F = 23; break;
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case 1: E = 11; F = 52; break;
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default: throw new ArgumentOutOfRangeException(nameof(Size));
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}
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long Value = (Imm & 0x3f) << F - 4;
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long EBit = (Imm >> 6) & 1;
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long SBit = (Imm >> 7) & 1;
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if (EBit != 0)
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{
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Value |= (1L << E - 3) - 1 << F + 2;
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}
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Value |= (EBit ^ 1) << F + E - 1;
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Value |= SBit << F + E;
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return Value;
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}
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public static long DecodeImm26_2(int OpCode)
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{
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return ((long)OpCode << 38) >> 36;
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}
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public static long DecodeImmS19_2(int OpCode)
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{
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return (((long)OpCode << 40) >> 43) & ~3;
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}
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public static long DecodeImmS14_2(int OpCode)
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{
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return (((long)OpCode << 45) >> 48) & ~3;
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}
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}
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} |