ring_elem RingZZ::remainderAndQuotient(const ring_elem f, const ring_elem g,
ring_elem ") const
{
mpz_ptr q = new_elem();
mpz_ptr r = new_elem();
int gsign = mpz_sgn(g.get_mpz());
mpz_t gg, ghalf;
mpz_init(gg);
mpz_init(ghalf);
mpz_abs(gg,g.get_mpz());
mpz_fdiv_qr(q, r, f.get_mpz(), gg);
mpz_tdiv_q_2exp(ghalf, gg, 1);
if (mpz_cmp(r,ghalf) > 0) // r > ghalf
{
mpz_sub(r,r,gg);
mpz_add_ui(q,q,1);
}
if (gsign < 0)
mpz_neg(q,q);
mpz_clear(gg);
mpz_clear(ghalf);
quot = ring_elem(q);
return ring_elem(r);
}
ring_elem RingZZ::gcd_extended(const ring_elem f, const ring_elem g,
ring_elem &u, ring_elem &v) const
{
mpz_ptr result = new_elem();
mpz_ptr u1 = new_elem();
mpz_ptr v1 = new_elem();
mpz_gcdext(result, u1, v1, f.get_mpz(), g.get_mpz());
u = ring_elem(u1);
v = ring_elem(v1);
return ring_elem(result);
}
ring_elem GF::from_int(int n) const
{
int m = n % P;
if (m < 0) m += P;
m = _from_int_table[m];
return ring_elem(m);
}
ring_elem RingZZ::from_int(mpz_ptr n) const
{
mpz_ptr result = new_elem();
mpz_set(result, n);
return ring_elem(result);
}
ring_elem Z_mod::invert(const ring_elem f) const
{
// MES: error if f == _ZERO
int a = f.int_val;
if (a == 0) return 0; // this is the case f == ONE
return ring_elem(P - 1 - a);
}
ring_elem Z_mod::from_long(long n) const
{
int m = static_cast<int>(n % P);
if (m < 0) m += P;
m = _log_table[m];
return ring_elem(m);
}
ring_elem Z_mod::from_int(int n) const
{
int m = n % P;
if (m < 0) m += P;
m = _log_table[m];
return ring_elem(m);
}
ring_elem RingZZ::from_long(long n) const
{
mpz_ptr result = new_elem();
mpz_set_si(result, n);
return ring_elem(result);
}
ring_elem RingZZ::copy(const ring_elem f) const
{
mpz_ptr a = f.get_mpz();
mpz_ptr result = new_elem();
mpz_set(result, a);
return ring_elem(result);
}
ring_elem GF::from_long(long n) const
{
long m1 = n % characteristic();
if (m1 < 0) m1 += characteristic();
int m = static_cast<int>(m1);
m = _from_int_table[m];
return ring_elem(m);
}
ring_elem GF::from_int(mpz_ptr n) const
{
mpz_t result;
mpz_init(result);
mpz_mod_ui(result, n, P);
int m = static_cast<int>(mpz_get_si(result));
if (m < 0) m += P;
m = _from_int_table[m];
return ring_elem(m);
}
ring_elem RingZZ::power(const ring_elem f, mpz_t n) const
{
mpz_ptr result = new_elem();
int n1;
if (!get_si(n1, n))
{ ERROR("exponent too large"); }
else
mpz_pow_ui(result, f.get_mpz(), n1);
return ring_elem(result);
}
ring_elem GF::from_int(mpz_ptr n) const
{
mpz_t result;
mpz_init(result);
mpz_mod_ui(result, n, characteristic());
long m1 = mpz_get_si(result);
mpz_clear(result);
if (m1 < 0) m1 += characteristic();
int m = static_cast<int>(m1);
m = _from_int_table[m];
return ring_elem(m);
}
ring_elem Z_mod::from_int(mpz_ptr n) const
{
// cout << "from_int(";
// bignum_text_out(cout, n);
// cout << ") = " << endl;
mpz_t result;
mpz_init(result);
mpz_mod_ui(result, n, P);
int m = static_cast<int>(mpz_get_si(result));
// cout << m << endl;
if (m < 0) m += P;
m = _log_table[m];
return ring_elem(m);
}
void RingZZ::lower_content(ring_elem &c, ring_elem g) const
// c is a content elem, g is in ring
{
if (is_zero(c))
{
c = g;
return;
}
gmp_ZZ result = RingZZ::new_elem();
mpz_srcptr a = c.get_mpz();
mpz_srcptr b = g.get_mpz();
mpz_gcd(result, a, b);
if(mpz_sgn(a) == -1)
mpz_neg(result, result);
c = ring_elem(result);
}
bool RingZZ::lower_associate_divisor(ring_elem &f, const ring_elem g) const
{
// This sets f to either 0, 1 or -1.
// if f is 0, do f=sign(g), else f=sign(f)
// return whether f is zero
gmp_ZZ result = RingZZ::new_elem();
mpz_ptr a = f.get_mpz();
mpz_ptr b = g.get_mpz();
int sa = mpz_sgn(a);
int sb = mpz_sgn(b);
int s = (sa == 0 ? sb : sa);
mpz_set_si(result,s);
f = ring_elem(result);
return !RingZZ::is_zero(f);
}
void RingZZ::lower_content(ring_elem &c, ring_elem g) const
// c is a content elem, g is in ring
{
// if f is 0, do f=sign(g), else f=sign(f)
// return whether f is zero
if (is_zero(c))
{
c = g;
return;
}
gmp_ZZ result = RingZZ::new_elem();
mpz_ptr a = c.get_mpz();
mpz_ptr b = g.get_mpz();
mpz_gcd(result,a,b);
c = ring_elem(result);
}
ring_elem GF::invert(const ring_elem f) const
{
// error if f == _ZERO
if (f == _ONE) return _ONE;
return ring_elem(Q1_ - f);
}
ring_elem RingZZ::negate(const ring_elem f) const
{
mpz_ptr result = new_elem();
mpz_sub(result, _zero_elem, f.get_mpz());
return ring_elem(result);
}
ring_elem Z_mod::random() const
{
int exp = rawRandomInt((int32_t)P);
return ring_elem(exp);
}
ring_elem GF::random() const
{
int exp = rawRandomInt((int32_t)Q_);
return ring_elem(exp);
}
ring_elem RingZZ::subtract(const ring_elem f, const ring_elem g) const
{
mpz_ptr result = new_elem();
mpz_sub(result, f.get_mpz(), g.get_mpz());
return ring_elem(result);
}
ring_elem RingZZ::gcd(const ring_elem f, const ring_elem g) const
{
mpz_ptr result = new_elem();
mpz_gcd(result, f.get_mpz(), g.get_mpz());
return ring_elem(result);
}
ring_elem RingZZ::power(const ring_elem f, int n) const
{
mpz_ptr result = new_elem();
mpz_pow_ui(result, f.get_mpz(), n);
return ring_elem(result);
}
ring_elem RingZZ::divide(const ring_elem f, const ring_elem g) const
{
mpz_ptr result = new_elem();
mpz_fdiv_q(result, f.get_mpz(), g.get_mpz());
return ring_elem(result);
}
