  L'Ecuyer & Simard's Big Crush statistical test suite has revealed statistical
flaws in many popular random number generators including Marsaglia's Xorshift
generators. Vigna recently proposed some 64-bit variations on the Xorshift
scheme that are further scrambled (i.e., Xorshift1024*, Xorshift1024+,
Xorshift128+, Xoroshiro128+). Unlike their unscrambled counterparts, they pass
Big Crush when interleaving blocks of 32 bits for each 64-bit word (most
significant, least significant, most significant, least significant, etc.). We
report that these scrambled generators systematically fail Big
Crush---specifically the linear-complexity and matrix-rank tests that detect
linearity---when taking the 32 lowest-order bits in reverse order from each
64-bit word.
