dab47db46b
fixes for: - mpn_sbpi1_div_qr_sec and mpn_sbpi1_div_r_sec - mpz_powm_ui - AMD family 11h - mpz_powm_sec and mpn_powm_sec - ASSERT() fixes - gcd, gcdext, and invert function fixes - some PPC division operations
103 lines
2.7 KiB
C
103 lines
2.7 KiB
C
/* mpz_cdiv_q_2exp, mpz_fdiv_q_2exp -- quotient from mpz divided by 2^n.
|
|
|
|
Copyright 1991, 1993, 1994, 1996, 1998, 1999, 2001, 2002, 2004, 2012 Free
|
|
Software Foundation, Inc.
|
|
|
|
This file is part of the GNU MP Library.
|
|
|
|
The GNU MP Library is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU Lesser General Public License as published by
|
|
the Free Software Foundation; either version 3 of the License, or (at your
|
|
option) any later version.
|
|
|
|
The GNU MP Library 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 Lesser General Public
|
|
License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public License
|
|
along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
|
|
|
|
#include "gmp.h"
|
|
#include "gmp-impl.h"
|
|
|
|
|
|
/* dir==1 for ceil, dir==-1 for floor */
|
|
|
|
static void __gmpz_cfdiv_q_2exp (REGPARM_3_1 (mpz_ptr, mpz_srcptr, mp_bitcnt_t, int)) REGPARM_ATTR (1);
|
|
#define cfdiv_q_2exp(w,u,cnt,dir) __gmpz_cfdiv_q_2exp (REGPARM_3_1 (w,u,cnt,dir))
|
|
|
|
REGPARM_ATTR (1) static void
|
|
cfdiv_q_2exp (mpz_ptr w, mpz_srcptr u, mp_bitcnt_t cnt, int dir)
|
|
{
|
|
mp_size_t wsize, usize, abs_usize, limb_cnt, i;
|
|
mp_srcptr up;
|
|
mp_ptr wp;
|
|
mp_limb_t round, rmask;
|
|
|
|
usize = SIZ (u);
|
|
abs_usize = ABS (usize);
|
|
limb_cnt = cnt / GMP_NUMB_BITS;
|
|
wsize = abs_usize - limb_cnt;
|
|
if (wsize <= 0)
|
|
{
|
|
/* u < 2**cnt, so result 1, 0 or -1 according to rounding */
|
|
PTR(w)[0] = 1;
|
|
SIZ(w) = (usize == 0 || (usize ^ dir) < 0 ? 0 : dir);
|
|
return;
|
|
}
|
|
|
|
/* +1 limb to allow for mpn_add_1 below */
|
|
MPZ_REALLOC (w, wsize+1);
|
|
|
|
/* Check for rounding if direction matches u sign.
|
|
Set round if we're skipping non-zero limbs. */
|
|
up = PTR(u);
|
|
round = 0;
|
|
rmask = ((usize ^ dir) >= 0 ? MP_LIMB_T_MAX : 0);
|
|
if (rmask != 0)
|
|
for (i = 0; i < limb_cnt && round == 0; i++)
|
|
round = up[i];
|
|
|
|
wp = PTR(w);
|
|
cnt %= GMP_NUMB_BITS;
|
|
if (cnt != 0)
|
|
{
|
|
round |= rmask & mpn_rshift (wp, up + limb_cnt, wsize, cnt);
|
|
wsize -= (wp[wsize - 1] == 0);
|
|
}
|
|
else
|
|
MPN_COPY_INCR (wp, up + limb_cnt, wsize);
|
|
|
|
if (round != 0)
|
|
{
|
|
if (wsize != 0)
|
|
{
|
|
mp_limb_t cy;
|
|
cy = mpn_add_1 (wp, wp, wsize, CNST_LIMB(1));
|
|
wp[wsize] = cy;
|
|
wsize += cy;
|
|
}
|
|
else
|
|
{
|
|
/* We shifted something to zero. */
|
|
wp[0] = 1;
|
|
wsize = 1;
|
|
}
|
|
}
|
|
SIZ(w) = (usize >= 0 ? wsize : -wsize);
|
|
}
|
|
|
|
|
|
void
|
|
mpz_cdiv_q_2exp (mpz_ptr w, mpz_srcptr u, mp_bitcnt_t cnt)
|
|
{
|
|
cfdiv_q_2exp (w, u, cnt, 1);
|
|
}
|
|
|
|
void
|
|
mpz_fdiv_q_2exp (mpz_ptr w, mpz_srcptr u, mp_bitcnt_t cnt)
|
|
{
|
|
cfdiv_q_2exp (w, u, cnt, -1);
|
|
}
|