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/*
Copyright (C) 2009 William Hart
Copyright (C) 2021 Daniel Schultz
Copyright (C) 2022 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 "gmpcompat.h"
#include "fmpz.h"
#include "fmpz/impl.h"
void fmpz_submul(fmpz_t f, const fmpz_t g, const fmpz_t h)
{
fmpz c1, c2, c3;
mpz_ptr mf;
c1 = *g;
c2 = *h;
c3 = *f;
/* todo: are the zero checks worth it for small input? */
if (c1 == 0 || c2 == 0)
return;
if (c3 == 0)
{
fmpz_mul(f, g, h);
fmpz_neg(f, f);
return;
}
if (!COEFF_IS_MPZ(c1)) /* g is small */
{
if (!COEFF_IS_MPZ(c2)) /* both are small */
{
ulong p1, p0;
smul_ppmm(p1, p0, -c1, c2);
if (!COEFF_IS_MPZ(c3))
{
ulong F1 = FLINT_SIGN_EXT(c3);
add_ssaaaa(p1, p0, p1, p0, F1, c3);
fmpz_set_signed_uiui(f, p1, p0);
}
else
{
mpz_ptr pF = COEFF_TO_PTR(c3);
flint_mpz_add_signed_uiui(pF, pF, p1, p0);
_fmpz_demote_val(f); /* cancellation may have occurred */
}
}
else
{
fmpz_addmul_si(f, h, -c1);
}
}
else if (!COEFF_IS_MPZ(c2)) /* h is small */
{
fmpz_addmul_si(f, g, -c2);
}
else
{
mf = _fmpz_promote_val(f);
_flint_mpz_addmul_large(mf, COEFF_TO_PTR(c1), COEFF_TO_PTR(c2), 1);
_fmpz_demote_val(f); /* cancellation may have occurred */
}
}
void fmpz_submul_si(fmpz_t f, const fmpz_t g, slong x)
{
fmpz F, G;
G = *g;
if (x == 0 || G == 0)
return;
F = *f;
if (F == 0)
{
fmpz_mul_si(f, g, x);
fmpz_neg(f, f);
return;
}
if (!COEFF_IS_MPZ(G))
{
ulong p1, p0;
smul_ppmm(p1, p0, G, x);
if (!COEFF_IS_MPZ(F))
{
ulong F1 = FLINT_SIGN_EXT(F);
sub_ddmmss(p1, p0, F1, F, p1, p0);
fmpz_set_signed_uiui(f, p1, p0);
}
else
{
mpz_ptr pF = COEFF_TO_PTR(F);
sub_ddmmss(p1, p0, UWORD(0), UWORD(0), p1, p0);
flint_mpz_add_signed_uiui(pF, pF, p1, p0);
_fmpz_demote_val(f);
}
}
else
{
mpz_ptr pG = COEFF_TO_PTR(G);
mpz_ptr pF = _fmpz_promote_val(f);
if (x < 0)
flint_mpz_addmul_ui(pF, pG, -(ulong) x);
else
flint_mpz_submul_ui(pF, pG, x);
_fmpz_demote_val(f);
}
}
void fmpz_submul_ui(fmpz_t f, const fmpz_t g, ulong x)
{
fmpz F, G;
G = *g;
if (x == 0 || G == 0)
return;
F = *f;
if (F == 0)
{
fmpz_mul_ui(f, g, x);
fmpz_neg(f, f);
return;
}
if (!COEFF_IS_MPZ(G))
{
ulong p1, p0;
if (x <= WORD_MAX)
{
smul_ppmm(p1, p0, -G, x);
}
else
{
umul_ppmm(p1, p0, FLINT_ABS(G), x);
if (G > 0)
{
p1 = -p1 - (p0 != 0);
p0 = -p0;
}
}
if (!COEFF_IS_MPZ(F))
{
ulong F1 = FLINT_SIGN_EXT(F);
add_ssaaaa(p1, p0, p1, p0, F1, F);
fmpz_set_signed_uiui(f, p1, p0);
}
else
{
mpz_ptr pF = COEFF_TO_PTR(F);
flint_mpz_add_signed_uiui(pF, pF, p1, p0);
_fmpz_demote_val(f);
}
}
else
{
mpz_ptr pG = COEFF_TO_PTR(G);
mpz_ptr pF = _fmpz_promote_val(f);
flint_mpz_submul_ui(pF, pG, x);
_fmpz_demote_val(f);
}
}