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normalise.c
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/*=============================================================================
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) 2012 Fredrik Johansson
******************************************************************************/
#include "fmpr.h"
long _fmpr_normalise(fmpz_t man, fmpz_t exp, long prec, fmpr_rnd_t rnd)
{
/* TODO: this should perhaps raise an exception to avoid ambiguity */
if (fmpz_is_zero(man))
{
fmpz_zero(exp);
return FMPR_RESULT_EXACT;
}
else
{
long bc, val;
bc = fmpz_bits(man);
val = fmpz_val2(man);
if (bc - val <= prec)
{
if (val != 0)
{
fmpz_tdiv_q_2exp(man, man, val);
fmpz_add_ui(exp, exp, val);
}
return FMPR_RESULT_EXACT;
}
else
{
long exp_shift = bc - prec;
if (rnd == FMPR_RND_NEAR)
{
abort();
}
else if (rnd == FMPR_RND_DOWN)
{
fmpz_tdiv_q_2exp(man, man, exp_shift);
}
else if (rnd == FMPR_RND_FLOOR)
{
fmpz_fdiv_q_2exp(man, man, exp_shift);
}
else if (rnd == FMPR_RND_CEIL)
{
fmpz_cdiv_q_2exp(man, man, exp_shift);
}
else
{
if (fmpz_sgn(man) > 0)
fmpz_cdiv_q_2exp(man, man, exp_shift);
else
fmpz_fdiv_q_2exp(man, man, exp_shift);
}
val = fmpz_val2(man);
exp_shift += val;
if (val != 0)
fmpz_tdiv_q_2exp(man, man, val);
fmpz_add_ui(exp, exp, exp_shift);
return val;
}
}
}