BN_MASK2l
dl = (d & BN_MASK2l);
q = BN_MASK2l;
l = (l & BN_MASK2l) << BN_BITS4;
#define LBITS(a) ((a) & BN_MASK2l)
#define HBITS(a) (((a) >> BN_BITS4) & BN_MASK2l)
m = (m & BN_MASK2l) << (BN_BITS4 + 1); \
: (to[(n) / 2] = ((m) & 1) ? (from[(m) / 2] >> 32) : (from[(m) / 2] & BN_MASK2l)))
#define bn_32_set_0(to, n) (((n) & 1) ? (to[(n) / 2] &= BN_MASK2l) : (to[(n) / 2] = 0));
r_d[BN_NIST_224_TOP - 1] &= BN_MASK2l;
ret = ((ret << BN_BITS4) | ((a->d[i] >> BN_BITS4) & BN_MASK2l)) % w;
ret = ((ret << BN_BITS4) | (a->d[i] & BN_MASK2l)) % w;