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.HighestBitSet((~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
});
}
