WBITS
tab |= (scalar1x->limb[bit / WBITS] >> (bit % WBITS) & 1) << k;
chain >>= WBITS;
accum = (accum + s->limb[i] - sc_p->limb[i]) >> WBITS;
out->limb[i] = out->limb[i] >> 1 | out->limb[i + 1] << (WBITS - 1);
out->limb[i] = out->limb[i] >> 1 | (c448_word_t)(chain << (WBITS - 1));
chain >>= WBITS;
chain >>= WBITS;
chain >>= WBITS;
chain >>= WBITS;
hi_carry = chain >> WBITS;