bn_nist.c

	nist_set_384(t_d, buf.bn,0,0,0,0,23,22,21,20,0,0,0,0);
	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
	/*S6*/
	nist_set_384(t_d,buf.bn,0,0,0,0,0,0,23,22,21,0,0,20);
	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
	/*D1*/
	nist_set_384(t_d,buf.bn,22,21,20,19,18,17,16,15,14,13,12,23);
	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
	/*D2*/
	nist_set_384(t_d,buf.bn,0,0,0,0,0,0,0,23,22,21,20,0);
	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
	/*D3*/
	nist_set_384(t_d,buf.bn,0,0,0,0,0,0,0,23,23,0,0,0);
	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);

	}
#endif
	/* see BN_nist_mod_224 for explanation */
	u.f = bn_sub_words;
	if (carry > 0)
		carry = (int)bn_sub_words(r_d,r_d,_nist_p_384[carry-1],BN_NIST_384_TOP);
	else if (carry < 0)
		{
		carry = (int)bn_add_words(r_d,r_d,_nist_p_384[-carry-1],BN_NIST_384_TOP);
		mask = 0-(PTR_SIZE_INT)carry;
		u.p = ((PTR_SIZE_INT)bn_sub_words&mask) |
		 ((PTR_SIZE_INT)bn_add_words&~mask);
		}
	else
		carry = 1;

	mask  = 0-(PTR_SIZE_INT)(*u.f)(c_d,r_d,_nist_p_384[0],BN_NIST_384_TOP);
	mask &= 0-(PTR_SIZE_INT)carry;
	res   = c_d;
	res   = (BN_ULONG *)(((PTR_SIZE_INT)res&~mask) |
	 ((PTR_SIZE_INT)r_d&mask));
	nist_cp_bn(r_d, res, BN_NIST_384_TOP);
	r->top = BN_NIST_384_TOP;
	bn_correct_top(r);

	return 1;
	}

#define BN_NIST_521_RSHIFT	(521%BN_BITS2)
#define BN_NIST_521_LSHIFT	(BN_BITS2-BN_NIST_521_RSHIFT)
#define BN_NIST_521_TOP_MASK	((BN_ULONG)BN_MASK2>>BN_NIST_521_LSHIFT)

int BN_nist_mod_521(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
	BN_CTX *ctx)
	{
	int	top = a->top, i;
	BN_ULONG *r_d, *a_d = a->d,
		 t_d[BN_NIST_521_TOP],
		 val,tmp,*res;
	PTR_SIZE_INT mask;
	static const BIGNUM _bignum_nist_p_521_sqr = {
		(BN_ULONG *)_nist_p_521_sqr,
		sizeof(_nist_p_521_sqr)/sizeof(_nist_p_521_sqr[0]),
		sizeof(_nist_p_521_sqr)/sizeof(_nist_p_521_sqr[0]),
		0,BN_FLG_STATIC_DATA };

	field = &_bignum_nist_p_521; /* just to make sure */

 	if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_521_sqr)>=0)
		return BN_nnmod(r, a, field, ctx);

	i = BN_ucmp(field, a);
	if (i == 0)
		{
		BN_zero(r);
		return 1;
		}
	else if (i > 0)
		return (r == a)? 1 : (BN_copy(r ,a) != NULL);

	if (r != a)
		{
		if (!bn_wexpand(r,BN_NIST_521_TOP))
			return 0;
		r_d = r->d;
		nist_cp_bn(r_d,a_d, BN_NIST_521_TOP);
		}
	else
		r_d = a_d;

	/* upper 521 bits, copy ... */
	nist_cp_bn_0(t_d,a_d + (BN_NIST_521_TOP-1), top - (BN_NIST_521_TOP-1),BN_NIST_521_TOP);
	/* ... and right shift */
	for (val=t_d[0],i=0; i<BN_NIST_521_TOP-1; i++)
		{
		t_d[i] = ( val>>BN_NIST_521_RSHIFT |
			  (tmp=t_d[i+1])<<BN_NIST_521_LSHIFT ) & BN_MASK2;
		val=tmp;
		}
	t_d[i] = val>>BN_NIST_521_RSHIFT;
	/* lower 521 bits */
	r_d[i] &= BN_NIST_521_TOP_MASK;

	bn_add_words(r_d,r_d,t_d,BN_NIST_521_TOP);
	mask = 0-(PTR_SIZE_INT)bn_sub_words(t_d,r_d,_nist_p_521,BN_NIST_521_TOP);
	res  = t_d;
	res  = (BN_ULONG *)(((PTR_SIZE_INT)res&~mask) |
	 ((PTR_SIZE_INT)r_d&mask));
	nist_cp_bn(r_d,res,BN_NIST_521_TOP);
	r->top = BN_NIST_521_TOP;
	bn_correct_top(r);

	return 1;
	}