/* 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);
}
/* divide this by m */
public virtual void div(BIG m)
{
int k = 0;
norm();
BIG e = new BIG(1);
BIG b = new BIG(this);
zero();
while (comp(b, m) >= 0)
{
e.fshl(1);
m.fshl(1);
k++;
}
while (k > 0)
{
m.fshr(1);
e.fshr(1);
if (comp(b, m) >= 0)
{
add(e);
norm();
b.sub(m);
b.norm();
}
k--;
}
}
/* reduce this mod m */
public virtual void mod(BIG m)
{
int k = 0;
norm();
if (comp(this, m) < 0)
{
return;
}
do
{
m.fshl(1);
k++;
} while (comp(this, m) >= 0);
while (k > 0)
{
m.fshr(1);
if (comp(this, m) >= 0)
{
sub(m);
norm();
}
k--;
}
}
/* convert from byte array to BIG */
public static BIG frombytearray(sbyte[] b, int n)
{
BIG m = new BIG(0);
for (int i = 0; i < ROM.MODBYTES; i++)
{
m.fshl(8);
m.w[0] += (int)b[i + n] & 0xff;
//m.inc((int)b[i]&0xff);
}
return(m);
}
/* this = -this mod Modulus */
public void neg()
{
int sb;
long ov;
BIG m = new BIG(p);
norm();
ov = BIG.EXCESS(x);
sb = 1;
while (ov != 0)
{
sb++;
ov >>= 1;
}
m.fshl(sb);
x.rsub(m);
if (BIG.EXCESS(x) >= ROM.FEXCESS)
{
reduce();
}
}