FYI, Hackers Delight uses a slight variation of Lemire's. He multiplies by 19/64 (so the divisor is a shift) and has the highest integer at the end of his table

FYI, Hackers Delight uses a slight variation of Lemire's. He multiplies by 19/64 (so the divisor is a shift) and has the highest integer at the end of his table (i.e. 2^64 - 1). He also uses a shift instead of a conditional, so his code is branchless. Generally I prefer this kind of approach. But, I suspect your digit counting is a very hot path so your tables will generally be in cache. So your approach will likely win anyway.