/* this*=c and catch overflow in DBIG */
public virtual DBIG pxmul(int c)
{
DBIG m = new DBIG(0);
long carry = 0;
for (int j = 0; j < ROM.NLEN; j++)
{
carry = m.muladd(w[j], (long)c, carry, j);
}
m.w[ROM.NLEN] = carry;
return(m);
}
/* return a^2 as DBIG */
public static DBIG sqr(BIG a)
{
DBIG c = new DBIG(0);
long carry;
a.norm();
for (int i = 0; i < ROM.NLEN; i++)
{
carry = 0;
for (int j = i + 1; j < ROM.NLEN; j++)
{
carry = c.muladd(2 * a.w[i], a.w[j], carry, i + j);
}
c.w[ROM.NLEN + i] = carry;
}
for (int i = 0; i < ROM.NLEN; i++)
{
c.w[2 * i + 1] += c.muladd(a.w[i], a.w[i], 0, 2 * i);
}
c.norm();
return(c);
}
/* return a*b as DBIG */
public static DBIG mul(BIG a, BIG b)
{
DBIG c = new DBIG(0);
long carry;
a.norm();
b.norm();
for (int i = 0; i < ROM.NLEN; i++)
{
carry = 0;
for (int j = 0; j < ROM.NLEN; j++)
{
carry = c.muladd(a.w[i], b.w[j], carry, i + j);
}
c.w[ROM.NLEN + i] = carry;
}
return(c);
}
/* reduce a DBIG to a BIG using the appropriate form of the modulus */
public static BIG mod(DBIG d)
{
BIG b;
if (ROM.MODTYPE == ROM.PSEUDO_MERSENNE)
{
long v, tw;
BIG t = d.Split(ROM.MODBITS);
b = new BIG(d);
unchecked
{
v = t.pmul((int)ROM.MConst);
}
tw = t.w[ROM.NLEN - 1];
t.w[ROM.NLEN - 1] &= ROM.TMASK;
t.w[0] += (ROM.MConst * ((tw >> ROM.TBITS) + (v << (ROM.BASEBITS - ROM.TBITS))));
b.add(t);
b.norm();
}
if (ROM.MODTYPE == ROM.MONTGOMERY_FRIENDLY)
{
for (int i = 0; i < ROM.NLEN; i++)
{
d.w[ROM.NLEN + i] += d.muladd(d.w[i], ROM.MConst - 1, d.w[i], ROM.NLEN + i - 1);
}
b = new BIG(0);
for (int i = 0; i < ROM.NLEN; i++)
{
b.w[i] = d.w[ROM.NLEN + i];
}
b.norm();
}
if (ROM.MODTYPE == ROM.NOT_SPECIAL)
{
BIG md = new BIG(ROM.Modulus);
long m, carry;
for (int i = 0; i < ROM.NLEN; i++)
{
if (ROM.MConst == -1)
{
m = (-d.w[i]) & ROM.MASK;
}
else
{
if (ROM.MConst == 1)
{
m = d.w[i];
}
else
{
m = (ROM.MConst * d.w[i]) & ROM.MASK;
}
}
carry = 0;
for (int j = 0; j < ROM.NLEN; j++)
{
carry = d.muladd(m, md.w[j], carry, i + j);
}
d.w[ROM.NLEN + i] += carry;
}
b = new BIG(0);
for (int i = 0; i < ROM.NLEN; i++)
{
b.w[i] = d.w[ROM.NLEN + i];
}
b.norm();
}
return(b);
}
