arb/mag/addmul.c
2014-05-08 14:48:36 +02:00

81 lines
2.3 KiB
C

/*=============================================================================
This file is part of ARB.
ARB is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
ARB is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with ARB; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2014 Fredrik Johansson
******************************************************************************/
#include "mag.h"
void
mag_addmul(mag_t z, const mag_t x, const mag_t y)
{
if (mag_is_zero(z))
{
mag_mul(z, x, y);
}
else if (mag_is_inf(z) || mag_is_inf(x) || mag_is_inf(y))
{
mag_inf(z);
}
else if (mag_is_zero(x) || mag_is_zero(y))
{
return;
}
else
{
long shift;
fmpz_t e;
fmpz_init(e);
/* x*y < 2^e */
_fmpz_add2_fast(e, MAG_EXPREF(x), MAG_EXPREF(y), 0);
shift = _fmpz_sub_small(MAG_EXPREF(z), e);
if (shift >= 0)
{
if (shift >= MAG_BITS)
MAG_MAN(z)++;
else
MAG_MAN(z) = MAG_MAN(z) + (MAG_FIXMUL(MAG_MAN(x),
MAG_MAN(y)) >> shift) + LIMB_ONE;
}
else
{
shift = -shift;
fmpz_swap(MAG_EXPREF(z), e);
if (shift >= MAG_BITS)
MAG_MAN(z) = MAG_FIXMUL(MAG_MAN(x), MAG_MAN(y))
+ (2 * LIMB_ONE);
else
MAG_MAN(z) = MAG_FIXMUL(MAG_MAN(x), MAG_MAN(y))
+ (MAG_MAN(z) >> shift) + (2 * LIMB_ONE);
MAG_ADJUST_ONE_TOO_SMALL(z);
}
MAG_ADJUST_ONE_TOO_LARGE(z);
fmpz_clear(e);
}
}