[heavenlyblue]

You don't need to cover all bits of the values, just 10 numeric values that can pass a a bounds check. That reduces the space to only 10K elements. With some bit shifting (and pre-validation) that should easily reduce the search space.

[nwellnhof]

Creating a LUT index with bit-shifting is essentially the same as parsing into an integer. Even if the LUT fits in L1 cache, I doubt it would be faster. If it doesn't fit, it's certainly slower.