static PyObject *
int_abs(PyIntObject *v)
{
if (v->ob_ival >= 0)
return int_pos(v);
else
return int_neg(v);
}
void int_gcd(BIGINT *u, BIGINT *v, BIGINT *w)
{
INDEX k, i, flag;
ELEMENT check, carry_bit;
BIGINT t, U, V;
int_copy( u, &U);
int_copy( v, &V);
/* find common powers of 2 and eliminate them */
k = 0;
/* check that both u and v are even */
while ( !(U.hw[INTMAX] & 1 || V.hw[INTMAX] & 1))
{
/* increment power of 2 and divide both u and v by 2 */
k++;
int_div2( &U);
int_div2( &V);
}
/* Now both u and v have been divided by 2^k.
If u is odd, set t = v and flag, otherwise t = u and clear flag */
if (U.hw[INTMAX] & 1)
{
int_copy( &V, &t);
flag = -1;
}
else
{
int_copy( &U, &t);
flag = 1;
}
check = 0;
INTLOOP (i) check |= t.hw[i];
while (check)
{
/* while t is even, divide by 2 */
while ( !(t.hw[INTMAX] & 1)) int_div2( &t);
/* reset u or v to t depending on sign of flag */
if (flag > 0) int_copy( &t, &U);
else int_copy( &t, &V);
/* t = u - v; core reduction step, gcd remains unchanged */
int_sub( &U, &V, &t);
if (t.hw[0] & MSB_HW)
{
flag = -1;
int_neg( &t);
}
else flag = 1;
check = 0;
INTLOOP (i) check |= t.hw[i];
}
/* reapply common powers of 2. First do words, then do bits.*/
int_copy( &U, w);
while ( k > HALFSIZE )
{
for (i=0; i<INTMAX; i++) w->hw[i] = w->hw[i+1];
k -= HALFSIZE;
w->hw[INTMAX] = 0;
}
carry_bit = 0;
while ( k > 0 )
{
INTLOOP (i)
{
w->hw[i] = (w->hw[i] << 1) | carry_bit;
carry_bit = w->hw[i] & CARRY ? 1 : 0;
w->hw[i] &= LOMASK;
}
k--;
}
}
