rygorous

static inline U32 ppcmask(U32 mb, U32 me)
{
   U32 maskmb = ~0u >> mb;
   U32 maskme = ~0u << (31 - me);
   return (mb <= me) ? maskmb & maskme : maskmb | maskme;
}

static inline U32 rotl32(U32 x, U32 amount)
{
   return (x << amount) | (x >> ((32 - amount) & 31));