nlz.sol

function nlz(uint x) pure returns (uint n) {
    uint y;
    n = 256;
    y = x >> 128; if (y != 0) { n = n - 128; x = y; }
    y = x >>  64; if (y != 0) { n = n -  64; x = y; }
    y = x >>  32; if (y != 0) { n = n -  32; x = y; }
    y = x >>  16; if (y != 0) { n = n -  16; x = y; }
    y = x >>   8; if (y != 0) { n = n -   8; x = y; }
    y = x >>   4; if (y != 0) { n = n -   4; x = y; }
    y = x >>   2; if (y != 0) { n = n -   2; x = y; }
    y = x >>   1; if (y != 0) return n - 2;
    return n - x;
}