mirror of
https://github.com/vale981/arb
synced 2025-03-05 09:21:38 -05:00
77 lines
2.2 KiB
C
77 lines
2.2 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) 2013 Fredrik Johansson
|
|
|
|
******************************************************************************/
|
|
|
|
#include "fmpr.h"
|
|
|
|
slong
|
|
fmpr_set_round_ui_2exp_fmpz(fmpr_t z,
|
|
mp_limb_t lo, const fmpz_t exp, int negative,
|
|
slong prec, fmpr_rnd_t rnd)
|
|
{
|
|
slong lead, trail, bc, shift, shift2, ret;
|
|
|
|
shift = 0;
|
|
|
|
if ((lo & 1) == 0)
|
|
{
|
|
if (lo == 0)
|
|
{
|
|
fmpr_zero(z);
|
|
return FMPR_RESULT_EXACT;
|
|
}
|
|
|
|
count_trailing_zeros(trail, lo);
|
|
lo >>= trail;
|
|
shift = trail;
|
|
}
|
|
|
|
count_leading_zeros(lead, lo);
|
|
bc = FLINT_BITS - lead;
|
|
|
|
ret = FMPR_RESULT_EXACT;
|
|
if (bc > prec)
|
|
{
|
|
shift2 = bc - prec;
|
|
lo = (lo >> shift2) + rounds_up(rnd, negative);
|
|
count_trailing_zeros(trail, lo);
|
|
lo >>= trail;
|
|
shift += shift2;
|
|
shift += trail;
|
|
ret = trail;
|
|
|
|
/* special case: if the mantissa overflowed to the next power of two,
|
|
the error bound must be multiplied by two */
|
|
ret -= (trail == prec);
|
|
}
|
|
|
|
if (!negative)
|
|
fmpz_set_ui(fmpr_manref(z), lo);
|
|
else
|
|
fmpz_neg_ui(fmpr_manref(z), lo);
|
|
|
|
fmpz_add_si_inline(fmpr_expref(z), exp, shift);
|
|
return ret;
|
|
}
|
|
|