1  /* mpf_ceil, mpf_floor -- round an mpf to an integer.
       2  
       3  Copyright 2001, 2004, 2012 Free Software Foundation, Inc.
       4  
       5  This file is part of the GNU MP Library.
       6  
       7  The GNU MP Library is free software; you can redistribute it and/or modify
       8  it under the terms of either:
       9  
      10    * the GNU Lesser General Public License as published by the Free
      11      Software Foundation; either version 3 of the License, or (at your
      12      option) any later version.
      13  
      14  or
      15  
      16    * the GNU General Public License as published by the Free Software
      17      Foundation; either version 2 of the License, or (at your option) any
      18      later version.
      19  
      20  or both in parallel, as here.
      21  
      22  The GNU MP Library is distributed in the hope that it will be useful, but
      23  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
      24  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
      25  for more details.
      26  
      27  You should have received copies of the GNU General Public License and the
      28  GNU Lesser General Public License along with the GNU MP Library.  If not,
      29  see https://www.gnu.org/licenses/.  */
      30  
      31  #include "gmp-impl.h"
      32  
      33  
      34  /* dir==1 for ceil, dir==-1 for floor
      35  
      36     Notice the use of prec+1 ensures mpf_ceil and mpf_floor are equivalent to
      37     mpf_set if u is already an integer.  */
      38  
      39  static void __gmpf_ceil_or_floor (REGPARM_2_1 (mpf_ptr, mpf_srcptr, int)) REGPARM_ATTR (1);
      40  #define mpf_ceil_or_floor(r,u,dir)  __gmpf_ceil_or_floor (REGPARM_2_1 (r, u, dir))
      41  
      42  REGPARM_ATTR (1) static void
      43  mpf_ceil_or_floor (mpf_ptr r, mpf_srcptr u, int dir)
      44  {
      45    mp_ptr     rp, up, p;
      46    mp_size_t  size, asize, prec;
      47    mp_exp_t   exp;
      48  
      49    size = SIZ(u);
      50    if (size == 0)
      51      {
      52      zero:
      53        SIZ(r) = 0;
      54        EXP(r) = 0;
      55        return;
      56      }
      57  
      58    rp = PTR(r);
      59    exp = EXP(u);
      60    if (exp <= 0)
      61      {
      62        /* u is only a fraction */
      63        if ((size ^ dir) < 0)
      64          goto zero;
      65        rp[0] = 1;
      66        EXP(r) = 1;
      67        SIZ(r) = dir;
      68        return;
      69      }
      70    EXP(r) = exp;
      71  
      72    up = PTR(u);
      73    asize = ABS (size);
      74    up += asize;
      75  
      76    /* skip fraction part of u */
      77    asize = MIN (asize, exp);
      78  
      79    /* don't lose precision in the copy */
      80    prec = PREC (r) + 1;
      81  
      82    /* skip excess over target precision */
      83    asize = MIN (asize, prec);
      84  
      85    up -= asize;
      86  
      87    if ((size ^ dir) >= 0)
      88      {
      89        /* rounding direction matches sign, must increment if ignored part is
      90           non-zero */
      91        for (p = PTR(u); p != up; p++)
      92          {
      93            if (*p != 0)
      94              {
      95                if (mpn_add_1 (rp, up, asize, CNST_LIMB(1)))
      96                  {
      97                    /* was all 0xFF..FFs, which have become zeros, giving just
      98                       a carry */
      99                    rp[0] = 1;
     100                    asize = 1;
     101                    EXP(r)++;
     102                  }
     103                SIZ(r) = (size >= 0 ? asize : -asize);
     104                return;
     105              }
     106          }
     107      }
     108  
     109    SIZ(r) = (size >= 0 ? asize : -asize);
     110    if (rp != up)
     111      MPN_COPY_INCR (rp, up, asize);
     112  }
     113  
     114  
     115  void
     116  mpf_ceil (mpf_ptr r, mpf_srcptr u)
     117  {
     118    mpf_ceil_or_floor (r, u, 1);
     119  }
     120  
     121  void
     122  mpf_floor (mpf_ptr r, mpf_srcptr u)
     123  {
     124    mpf_ceil_or_floor (r, u, -1);
     125  }