function log_2 (uint128 x)
...
b = b * b >> 127; if (b >= 0x100000000000000000000000000000000) {b >>= 1; l |= 0x1000000000000000000000000000000;}
function log_2(uint128 x)
...
b = b * b >> 127; if(b > 0x100000000000000000000000000000000) {b >>= 1; l |= 0x1000000000000000000000000000000;}
