void t_INT_to_ZZ ( mpz_t value, GEN g )
{
long limbs = 0;
limbs = lgefint(g) - 2;
mpz_realloc2( value, limbs );
mpz_import( value, limbs, -1, sizeof(long), 0, 0, int_LSW(g) );
if ( signe(g) == -1 )
mpz_neg( value, value );
return;
}
GEN
shallowextract(GEN x, GEN L)
{
long i,j, tl = typ(L), tx = typ(x), lx = lg(x);
GEN y;
switch(tx)
{
case t_VEC:
case t_COL:
case t_MAT:
case t_VECSMALL: break;
default: pari_err_TYPE("extract",x);
}
if (tl==t_INT)
{ /* extract components of x as per the bits of mask L */
long k, l, ix, iy, maxj;
GEN Ld;
if (!signe(L)) return cgetg(1,tx);
y = new_chunk(lx);
l = lgefint(L)-1; ix = iy = 1;
maxj = BITS_IN_LONG - bfffo(*int_MSW(L));
if ((l-2) * BITS_IN_LONG + maxj >= lx)
pari_err_TYPE("vecextract [mask too large]", L);
for (k = 2, Ld = int_LSW(L); k < l; k++, Ld = int_nextW(Ld))
{
ulong B = *Ld;
for (j = 0; j < BITS_IN_LONG; j++, B >>= 1, ix++)
if (B & 1) y[iy++] = x[ix];
}
{ /* k = l */
ulong B = *Ld;
for (j = 0; j < maxj; j++, B >>= 1, ix++)
if (B & 1) y[iy++] = x[ix];
}
y[0] = evaltyp(tx) | evallg(iy);
return y;
}