Coverage Report

Created: 2025-03-06 07:58

/src/gmp/mpz/cfdiv_q_2exp.c
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/* mpz_cdiv_q_2exp, mpz_fdiv_q_2exp -- quotient from mpz divided by 2^n.
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Copyright 1991, 1993, 1994, 1996, 1998, 1999, 2001, 2002, 2004, 2012,
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2015 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of either:
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  * the GNU Lesser General Public License as published by the Free
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    Software Foundation; either version 3 of the License, or (at your
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    option) any later version.
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or
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  * the GNU General Public License as published by the Free Software
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    Foundation; either version 2 of the License, or (at your option) any
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    later version.
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or both in parallel, as here.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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for more details.
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You should have received copies of the GNU General Public License and the
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GNU Lesser General Public License along with the GNU MP Library.  If not,
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see https://www.gnu.org/licenses/.  */
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#include "gmp-impl.h"
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/* dir==1 for ceil, dir==-1 for floor */
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static void __gmpz_cfdiv_q_2exp (REGPARM_3_1 (mpz_ptr, mpz_srcptr, mp_bitcnt_t, int)) REGPARM_ATTR (1);
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#define cfdiv_q_2exp(w,u,cnt,dir)  __gmpz_cfdiv_q_2exp (REGPARM_3_1 (w,u,cnt,dir))
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REGPARM_ATTR (1) static void
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cfdiv_q_2exp (mpz_ptr w, mpz_srcptr u, mp_bitcnt_t cnt, int dir)
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{
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  mp_size_t  wsize, usize, abs_usize, limb_cnt, i;
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  mp_srcptr  up;
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  mp_ptr     wp;
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  mp_limb_t  round, rmask;
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  usize = SIZ (u);
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  abs_usize = ABS (usize);
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  limb_cnt = cnt / GMP_NUMB_BITS;
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  wsize = abs_usize - limb_cnt;
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  if (wsize <= 0)
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    {
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      /* u < 2**cnt, so result 1, 0 or -1 according to rounding */
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      MPZ_NEWALLOC (w, 1)[0] = 1;
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      SIZ(w) = (usize == 0 || (usize ^ dir) < 0 ? 0 : dir);
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      return;
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    }
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  /* +1 limb to allow for mpn_add_1 below */
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  wp = MPZ_REALLOC (w, wsize+1);
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  /* Check for rounding if direction matches u sign.
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     Set round if we're skipping non-zero limbs.  */
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  up = PTR(u);
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  round = 0;
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  rmask = ((usize ^ dir) >= 0 ? MP_LIMB_T_MAX : 0);
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  if (rmask != 0)
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    for (i = 0; i < limb_cnt && round == 0; i++)
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      round = up[i];
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  cnt %= GMP_NUMB_BITS;
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  if (cnt != 0)
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    {
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      round |= rmask & mpn_rshift (wp, up + limb_cnt, wsize, cnt);
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      wsize -= (wp[wsize - 1] == 0);
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    }
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  else
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    MPN_COPY_INCR (wp, up + limb_cnt, wsize);
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  if (round != 0)
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    {
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      if (wsize != 0)
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  {
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    mp_limb_t cy;
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    cy = mpn_add_1 (wp, wp, wsize, CNST_LIMB(1));
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    wp[wsize] = cy;
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    wsize += cy;
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  }
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      else
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  {
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    /* We shifted something to zero.  */
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    wp[0] = 1;
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    wsize = 1;
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  }
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    }
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  SIZ(w) = (usize >= 0 ? wsize : -wsize);
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}
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void
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mpz_cdiv_q_2exp (mpz_ptr w, mpz_srcptr u, mp_bitcnt_t cnt)
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{
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  cfdiv_q_2exp (w, u, cnt, 1);
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}
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void
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mpz_fdiv_q_2exp (mpz_ptr w, mpz_srcptr u, mp_bitcnt_t cnt)
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{
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  cfdiv_q_2exp (w, u, cnt, -1);
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}