IsEnabledX2 returns true if the architecture supports a two-way SIMD implementation provided in this package.

IsEnabledX4 returns true if the architecture supports a four-way SIMD implementation provided in this package.

StateX2 contains state for the two-way permutation including the two interleaved [25]uint64 buffers.

StateX4 contains state for the four-way permutation including the four interleaved [25]uint64 buffers.