if (BN_is_zero(&(val1[0])))
if (BN_is_zero(a_mod_m))
int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,	const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m,	BN_CTX *ctx, BN_MONT_CTX *in_mont)	{	int i,j,bits,b,bits1,bits2,ret=0,wpos1,wpos2,window1,window2,wvalue1,wvalue2;	int r_is_one=1,ts1=0,ts2=0;	BIGNUM *d,*r;	const BIGNUM *a_mod_m;	BIGNUM val1[TABLE_SIZE], val2[TABLE_SIZE];	BN_MONT_CTX *mont=NULL;	bn_check_top(a1);	bn_check_top(p1);	bn_check_top(a2);	bn_check_top(p2);	bn_check_top(m);	if (!(m->d[0] & 1))		{		BNerr(BN_F_BN_MOD_EXP2_MONT,BN_R_CALLED_WITH_EVEN_MODULUS);		return(0);		}	bits1=BN_num_bits(p1);	bits2=BN_num_bits(p2);	if ((bits1 == 0) && (bits2 == 0))		{		ret = BN_one(rr);		return ret;		}		bits=(bits1 > bits2)?bits1:bits2;	BN_CTX_start(ctx);	d = BN_CTX_get(ctx);	r = BN_CTX_get(ctx);	if (d == NULL || r == NULL) goto err;	if (in_mont != NULL)		mont=in_mont;	else		{		if ((mont=BN_MONT_CTX_new()) == NULL) goto err;		if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;		}	window1 = BN_window_bits_for_exponent_size(bits1);	window2 = BN_window_bits_for_exponent_size(bits2);	/*	 * Build table for a1:   val1[i] := a1^(2*i + 1) mod m  for i = 0 .. 2^(window1-1)	 */	BN_init(&val1[0]);	ts1=1;	if (a1->neg || BN_ucmp(a1,m) >= 0)		{		if (!BN_mod(&(val1[0]),a1,m,ctx))			goto err;		a_mod_m = &(val1[0]);		}	else		a_mod_m = a1;	if (BN_is_zero(&(val1[0])))		{		ret = BN_zero(rr);		goto err;		}	if (!BN_to_montgomery(&(val1[0]),a_mod_m,mont,ctx)) goto err;	if (window1 > 1)		{		if (!BN_mod_mul_montgomery(d,&(val1[0]),&(val1[0]),mont,ctx)) goto err;		j=1<<(window1-1);		for (i=1; i<j; i++)			{			BN_init(&(val1[i]));			if (!BN_mod_mul_montgomery(&(val1[i]),&(val1[i-1]),d,mont,ctx))				goto err;			}		ts1=i;		}	/*	 * Build table for a2:   val2[i] := a2^(2*i + 1) mod m  for i = 0 .. 2^(window2-1)	 */	BN_init(&val2[0]);	ts2=1;	if (a2->neg || BN_ucmp(a2,m) >= 0)		{		if (!BN_mod(&(val2[0]),a2,m,ctx))			goto err;		a_mod_m = &(val2[0]);		}	else		a_mod_m = a2;	if (BN_is_zero(&(val2[0])))		{		ret = BN_zero(rr);		goto err;		}	if (!BN_to_montgomery(&(val2[0]),a_mod_m,mont,ctx)) goto err;	if (window2 > 1)		{		if (!BN_mod_mul_montgomery(d,&(val2[0]),&(val2[0]),mont,ctx)) goto err;		j=1<<(window2-1);		for (i=1; i<j; i++)			{			BN_init(&(val2[i]));			if (!BN_mod_mul_montgomery(&(val2[i]),&(val2[i-1]),d,mont,ctx))				goto err;			}		ts2=i;		}	/* Now compute the power product, using independent windows. */	r_is_one=1;	wvalue1=0;  /* The 'value' of the first window */	wvalue2=0;  /* The 'value' of the second window */	wpos1=0;    /* If wvalue1 > 0, the bottom bit of the first window */	wpos2=0;    /* If wvalue2 > 0, the bottom bit of the second window */	if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;	for (b=bits-1; b>=0; b--)		{		if (!r_is_one)			{			if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))				goto err;			}				if (!wvalue1)			if (BN_is_bit_set(p1, b))				{				/* consider bits b-window1+1 .. b for this window */				i = b-window1+1;				while (!BN_is_bit_set(p1, i)) /* works for i<0 */					i++;				wpos1 = i;				wvalue1 = 1;				for (i = b-1; i >= wpos1; i--)					{					wvalue1 <<= 1;					if (BN_is_bit_set(p1, i))						wvalue1++;					}				}				if (!wvalue2)			if (BN_is_bit_set(p2, b))				{				/* consider bits b-window2+1 .. b for this window */				i = b-window2+1;				while (!BN_is_bit_set(p2, i))					i++;				wpos2 = i;				wvalue2 = 1;				for (i = b-1; i >= wpos2; i--)					{					wvalue2 <<= 1;					if (BN_is_bit_set(p2, i))						wvalue2++;					}				}		if (wvalue1 && b == wpos1)			{			/* wvalue1 is odd and < 2^window1 */			if (!BN_mod_mul_montgomery(r,r,&(val1[wvalue1>>1]),mont,ctx))				goto err;			wvalue1 = 0;			r_is_one = 0;			}				if (wvalue2 && b == wpos2)			{			/* wvalue2 is odd and < 2^window2 */			if (!BN_mod_mul_montgomery(r,r,&(val2[wvalue2>>1]),mont,ctx))				goto err;			wvalue2 = 0;			r_is_one = 0;			}		}	BN_from_montgomery(rr,r,mont,ctx);	ret=1;err:	if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);	BN_CTX_end(ctx);	for (i=0; i<ts1; i++)		BN_clear_free(&(val1[i]));	for (i=0; i<ts2; i++)		BN_clear_free(&(val2[i]));	return(ret);	}