BN_NIST_521_RSHIFT
#define BN_NIST_521_LSHIFT (BN_BITS2 - BN_NIST_521_RSHIFT)
tmp = val >> BN_NIST_521_RSHIFT;
t_d[i] = (val >> BN_NIST_521_RSHIFT | (tmp = t_d[i + 1]) << BN_NIST_521_LSHIFT) & BN_MASK2;
t_d[i] = val >> BN_NIST_521_RSHIFT;