/// <summary>
/// Xors the two bit fields, respecting the upper 32 bits as an ID.
/// </summary>
/// <param name="bitsA">The most significant bits of Tag A.</param>
/// <param name="bitsB">The most significant bits of Tag B.</param>
/// <returns>The most significant bits of Tag A XOR Tag B.</returns>
internal static ulong TranspileXor(ulong bitsA, ulong bitsB)
{
ulong result = GetLowerBits(bitsA) ^ GetLowerBits(bitsB);
int ubA = GetUpperBits(bitsA), ubB = GetUpperBits(bitsB), ubResult;
if (ubA == 0)
{
ubResult = ubB;
}
else if (ubB == 0)
{
ubResult = ubA;
}
else
{
// Both nonzero
var inst = ExtendedTagBits.Instance;
var bitSetA = BitSetPool.Allocate();
bitSetA.SetTo(inst.GetTagBits(ubA));
bitSetA.Xor(inst.GetTagBits(ubB));
ubResult = inst.GetIDWithBits(bitSetA);
BitSetPool.Recycle(bitSetA);
}
return(result | ((ulong)ubResult << 32));
}
private static ulong NotHighBits(ulong bits)
{
int ubA = GetUpperBits(bits);
var inst = ExtendedTagBits.Instance;
var notSet = BitSetPool.Allocate();
notSet.SetTo(inst.GetTagBits(ubA));
notSet.Not(MAX_BITS);
int id = inst.GetIDWithBits(notSet);
BitSetPool.Recycle(notSet);
return((ulong)id << 32);
}
/// <summary>
/// Gets the ID to use for tag bits that have the specified ID cleared.
/// </summary>
/// <param name="id">The existing ID.</param>
/// <param name="extIndex">The tag index to clear.</param>
/// <returns>A new or reused ID with that tag bit clear.</returns>
public int GetIDWithTagClear(int id, int extIndex)
{
if (id < INITIAL_TAG_BITS)
{
// Cleared a tag bit in the initial 1024
id = (id == extIndex + 1) ? 0 : id;
}
else
{
var bits = BitSetPool.Allocate();
bits.SetTo(GetTagBits(id));
bits.Set(extIndex, false);
id = GetIDWithBits(bits);
BitSetPool.Recycle(bits);
}
return(id);
}
/// <summary>
/// Gets the ID to use for tag bits that have the specified ID set.
/// </summary>
/// <param name="id">The existing ID.</param>
/// <param name="extIndex">The tag index to set.</param>
/// <returns>A new or reused ID with that tag bit set.</returns>
public int GetIDWithTagSet(int id, int extIndex)
{
if ((extIndex >= INITIAL_TAG_BITS || id != 0) && id != extIndex + 1)
{
var bits = BitSetPool.Allocate();
bits.SetTo(GetTagBits(id));
bits.Set(extIndex, true);
id = GetIDWithBits(bits);
BitSetPool.Recycle(bits);
}
else
{
// All bits are clear, use the optimized route to avoid allocating
id = extIndex + 1;
}
return(id);
}