# Tag Info

The operation: X[16] & (N-1) is really, mathematically speaking: $$X[16] \mathrm{\ mod\ } N$$ With a generic $N$, this operation must be done with an actual division, which is expensive; some CPU types don't provide it, and for CPU which do provide it (e.g. x86), it is quite slow (for instance, for 32-bit operands on an Intel Core2, division latency ...