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/*
Copyright (C) 2009 William Hart
Copyright (C) 2010 Sebastian Pancratz
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 "gmpcompat.h"
#include "fmpz.h"
void
fmpz_divexact(fmpz_t f, const fmpz_t g, const fmpz_t h)
{
fmpz c1 = *g;
fmpz c2 = *h;
if (fmpz_is_zero(h))
{
flint_throw(FLINT_DIVZERO, "Exception (fmpz_divexact). Division by zero.\n");
}
if (!COEFF_IS_MPZ(c1)) /* g is small, h must be also or division isn't exact */
{
fmpz_set_si(f, c1 / c2);
}
else /* g is large */
{
mpz_ptr mf;
if (!COEFF_IS_MPZ(c2)) /* h is small */
{
mf = _fmpz_promote(f);
if (c2 > 0) /* h > 0 */
{
flint_mpz_divexact_ui(mf, COEFF_TO_PTR(c1), c2);
}
else
{
flint_mpz_divexact_ui(mf, COEFF_TO_PTR(c1), -c2);
mpz_neg(mf, mf);
}
_fmpz_demote_val(f); /* division by h may result in small value */
}
else /* both are large */
{
if (MPZ_WANT_FLINT_DIVISION(COEFF_TO_PTR(c1), COEFF_TO_PTR(c2)))
{
_fmpz_divexact_newton(f, g, h);
}
else
{
mf = _fmpz_promote(f);
mpz_divexact(mf, COEFF_TO_PTR(c1), COEFF_TO_PTR(c2));
_fmpz_demote_val(f); /* division by h may result in small value */
}
}
}
}
void fmpz_divexact_si(fmpz_t f, const fmpz_t g, slong h)
{
fmpz c1 = *g;
if (h == 0)
{
flint_throw(FLINT_DIVZERO, "Exception (fmpz_divexact_si). Division by zero.\n");
}
if (!COEFF_IS_MPZ(c1)) /* g is small */
{
fmpz_set_si(f, c1 / h);
}
else /* g is large */
{
mpz_ptr mf = _fmpz_promote(f);
if (h > 0)
{
flint_mpz_divexact_ui(mf, COEFF_TO_PTR(c1), h);
_fmpz_demote_val(f); /* division by h may result in small value */
}
else
{
flint_mpz_divexact_ui(mf, COEFF_TO_PTR(c1), -(ulong) h);
_fmpz_demote_val(f); /* division by h may result in small value */
fmpz_neg(f, f);
}
}
}
void fmpz_divexact_ui(fmpz_t f, const fmpz_t g, ulong h)
{
fmpz c1 = *g;
if (h == 0)
{
flint_throw(FLINT_DIVZERO, "Exception (fmpz_divexact_ui). Division by zero.\n");
}
if (!COEFF_IS_MPZ(c1)) /* g is small */
{
fmpz_set_si(f, c1 / (slong) h);
}
else /* g is large */
{
mpz_ptr mf = _fmpz_promote(f);
flint_mpz_divexact_ui(mf, COEFF_TO_PTR(c1), h);
_fmpz_demote_val(f); /* division by h may result in small value */
}
}
#if defined(__GNUC__)
void fmpz_divexact2_uiui(fmpz_t f, const fmpz_t g, ulong h1, ulong h2)
{
ulong hx;
int of;
/* builtin for better handling of overflow */
of = __builtin_mul_overflow(h1, h2, &hx);
if (!of)
{
fmpz_divexact_ui(f, g, hx);
}
else
{
fmpz_divexact_ui(f, g, h1);
fmpz_divexact_ui(f, f, h2);
}
}
#else
void fmpz_divexact2_uiui(fmpz_t f, const fmpz_t g, ulong h1, ulong h2)
{
ulong hi, lo;
umul_ppmm(hi, lo, h1, h2);
if (!hi)
{
fmpz_divexact_ui(f, g, lo);
}
else
{
fmpz_divexact_ui(f, g, h1);
fmpz_divexact_ui(f, f, h2);
}
}
#endif