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/*
Copyright (C) 2021 Fredrik Johansson
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "fmpz_extras.h"
#include "fexpr.h"
int
fexpr_get_fmpz(fmpz_t c, const fexpr_t x)
{
ulong head = x->data[0];
if (FEXPR_TYPE(head) == FEXPR_TYPE_SMALL_INT)
{
_fmpz_demote(c);
*c = ((slong) head) >> FEXPR_TYPE_BITS;
}
else
{
slong nlimbs;
int negative;
nlimbs = FEXPR_SIZE(head) - 1;
if (FEXPR_TYPE(head) == FEXPR_TYPE_BIG_INT_POS)
{
negative = 0;
}
else if (FEXPR_TYPE(head) == FEXPR_TYPE_BIG_INT_NEG)
{
negative = 1;
}
else
{
return 0;
}
if (nlimbs == 1 && x->data[1] <= COEFF_MAX)
{
_fmpz_demote(c);
*c = negative ? (-(slong) x->data[1]) : x->data[1];
}
else
{
fmpz_set_mpn_large(c, x->data + 1, nlimbs, negative);
}
}
return 1;
}