__log2
uint32_t __log2(uint32_t);
hashp->BSHIFT = __log2((uint32_t)hashp->BSIZE);
hashp->BSHIFT = __log2(info->bsize);
l2 = __log2(MAX((uint32_t)nelem, 2));
nsegs = 1 << __log2(nsegs);
spare_ndx = __log2((uint32_t)(hashp->MAX_BUCKET + 1));
((B) ? hashp->SPARES[__log2((uint32_t)((B)+1))-1] : 0)