112 lines
2.8 KiB
C#
112 lines
2.8 KiB
C#
using System;
|
|
|
|
namespace ChocolArm64.Decoders
|
|
{
|
|
static class DecoderHelper
|
|
{
|
|
public struct BitMask
|
|
{
|
|
public long WMask;
|
|
public long TMask;
|
|
public int Pos;
|
|
public int Shift;
|
|
public bool IsUndefined;
|
|
|
|
public static BitMask Invalid => new BitMask { IsUndefined = true };
|
|
}
|
|
|
|
public static BitMask DecodeBitMask(int opCode, bool immediate)
|
|
{
|
|
int immS = (opCode >> 10) & 0x3f;
|
|
int immR = (opCode >> 16) & 0x3f;
|
|
|
|
int n = (opCode >> 22) & 1;
|
|
int sf = (opCode >> 31) & 1;
|
|
|
|
int length = BitUtils.HighestBitSet32((~immS & 0x3f) | (n << 6));
|
|
|
|
if (length < 1 || (sf == 0 && n != 0))
|
|
{
|
|
return BitMask.Invalid;
|
|
}
|
|
|
|
int size = 1 << length;
|
|
|
|
int levels = size - 1;
|
|
|
|
int s = immS & levels;
|
|
int r = immR & levels;
|
|
|
|
if (immediate && s == levels)
|
|
{
|
|
return BitMask.Invalid;
|
|
}
|
|
|
|
long wMask = BitUtils.FillWithOnes(s + 1);
|
|
long tMask = BitUtils.FillWithOnes(((s - r) & levels) + 1);
|
|
|
|
if (r > 0)
|
|
{
|
|
wMask = BitUtils.RotateRight(wMask, r, size);
|
|
wMask &= BitUtils.FillWithOnes(size);
|
|
}
|
|
|
|
return new BitMask()
|
|
{
|
|
WMask = BitUtils.Replicate(wMask, size),
|
|
TMask = BitUtils.Replicate(tMask, size),
|
|
|
|
Pos = immS,
|
|
Shift = immR
|
|
};
|
|
}
|
|
|
|
public static long DecodeImm8Float(long imm, int size)
|
|
{
|
|
int e = 0, f = 0;
|
|
|
|
switch (size)
|
|
{
|
|
case 0: e = 8; f = 23; break;
|
|
case 1: e = 11; f = 52; break;
|
|
|
|
default: throw new ArgumentOutOfRangeException(nameof(size));
|
|
}
|
|
|
|
long value = (imm & 0x3f) << f - 4;
|
|
|
|
long eBit = (imm >> 6) & 1;
|
|
long sBit = (imm >> 7) & 1;
|
|
|
|
if (eBit != 0)
|
|
{
|
|
value |= (1L << e - 3) - 1 << f + 2;
|
|
}
|
|
|
|
value |= (eBit ^ 1) << f + e - 1;
|
|
value |= sBit << f + e;
|
|
|
|
return value;
|
|
}
|
|
|
|
public static long DecodeImm24_2(int opCode)
|
|
{
|
|
return ((long)opCode << 40) >> 38;
|
|
}
|
|
|
|
public static long DecodeImm26_2(int opCode)
|
|
{
|
|
return ((long)opCode << 38) >> 36;
|
|
}
|
|
|
|
public static long DecodeImmS19_2(int opCode)
|
|
{
|
|
return (((long)opCode << 40) >> 43) & ~3;
|
|
}
|
|
|
|
public static long DecodeImmS14_2(int opCode)
|
|
{
|
|
return (((long)opCode << 45) >> 48) & ~3;
|
|
}
|
|
}
|
|
} |