> Your suggested code seems work fine, let me run more test and send > v2, I guess I just don’t know how to explain why it work in comment > :p
If it's too convoluted maybe we should rather not use it :D The idea is for factor % (vlenb / potential_div) == 0 we're actually looking for the largest power of 2 that factor and vlenb are both a multiple of. (Individually) for factor the largest pow2 can be calculated by ctz (factor). Same for vlenb via ctz (vlenb). If ctz (factor) >= ctz (vlenb), vlenb already divides factor evenly. Otherwise, i.e. when ctz (factor) = 1 (divisible by 2) and ctz (vlenb) = 4 (divisible by 16) we need to divide vlenb by the pow2 difference 1 << (4 - 1). I just realize that the explanation is longer than the code before, maybe not a good sign ;) Regards Robin
