/* reduces this DBIG mod a DBIG in place */
/* public void mod(DBIG m)
* {
* int k=0;
* if (comp(this,m)<0) return;
*
* do
* {
* m.shl(1);
* k++;
* }
* while (comp(this,m)>=0);
*
* while (k>0)
* {
* m.shr(1);
* if (comp(this,m)>=0)
* {
* sub(m);
* norm();
* }
* k--;
* }
* return;
*
* }*/
/* return this/c */
public virtual BIG div(BIG c)
{
int k = 0;
DBIG m = new DBIG(c);
BIG a = new BIG(0);
BIG e = new BIG(1);
norm();
while (comp(this, m) >= 0)
{
e.fshl(1);
m.shl(1);
k++;
}
while (k > 0)
{
m.shr(1);
e.shr(1);
if (comp(this, m) > 0)
{
a.add(e);
a.norm();
sub(m);
norm();
}
k--;
}
return(a);
}
/* Create random BIG in portable way, one bit at a time */
public static BIG randomnum(BIG q, RAND rng)
{
DBIG d = new DBIG(0);
int i, b, j = 0, r = 0;
for (i = 0; i < 2 * ROM.MODBITS; i++)
{
if (j == 0)
{
r = rng.Byte;
}
else
{
r >>= 1;
}
b = r & 1;
d.shl(1);
d.w[0] += b; // m.inc(b);
j++;
j &= 7;
}
BIG m = d.mod(q);
return(m);
}
/* reduces this DBIG mod a BIG, and returns the BIG */
public virtual BIG mod(BIG c)
{
int k = 0;
norm();
DBIG m = new DBIG(c);
if (comp(this, m) < 0)
{
return(new BIG(this));
}
do
{
m.shl(1);
k++;
} while (comp(this, m) >= 0);
while (k > 0)
{
m.shr(1);
if (comp(this, m) >= 0)
{
sub(m);
norm();
}
k--;
}
return(new BIG(this));
}
/* convert to Montgomery n-residue form */
public void nres()
{
if (ROM.MODTYPE != ROM.PSEUDO_MERSENNE)
{
DBIG d = new DBIG(x);
d.shl(ROM.NLEN * ROM.BASEBITS);
x.copy(d.mod(p));
}
}
