github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpf/ui_div.c (about)

     1  /* mpf_ui_div -- Divide an unsigned integer with a float.
     2  
     3  Copyright 1993-1996, 2000-2002, 2004, 2005, 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 <stdio.h>  /* for NULL */
    32  #include "gmp.h"
    33  #include "gmp-impl.h"
    34  #include "longlong.h"
    35  
    36  
    37  void
    38  mpf_ui_div (mpf_ptr r, unsigned long int u, mpf_srcptr v)
    39  {
    40    mp_srcptr vp;
    41    mp_ptr rp, tp, remp, new_vp;
    42    mp_size_t vsize;
    43    mp_size_t rsize, prospective_rsize, zeros, tsize, high_zero;
    44    mp_size_t sign_quotient;
    45    mp_size_t prec;
    46    mp_exp_t rexp;
    47    TMP_DECL;
    48  
    49    vsize = v->_mp_size;
    50    sign_quotient = vsize;
    51  
    52    if (UNLIKELY (vsize == 0))
    53      DIVIDE_BY_ZERO;
    54  
    55    if (UNLIKELY (u == 0))
    56      {
    57        r->_mp_size = 0;
    58        r->_mp_exp = 0;
    59        return;
    60      }
    61  
    62    vsize = ABS (vsize);
    63    prec = r->_mp_prec;
    64  
    65    TMP_MARK;
    66    rexp = 1 - v->_mp_exp + 1;
    67  
    68    rp = r->_mp_d;
    69    vp = v->_mp_d;
    70  
    71    prospective_rsize = 1 - vsize + 1;    /* quot from using given u,v sizes */
    72    rsize = prec + 1;                     /* desired quot size */
    73  
    74    zeros = rsize - prospective_rsize;    /* padding u to give rsize */
    75    tsize = 1 + zeros;                    /* u with zeros */
    76  
    77    if (WANT_TMP_DEBUG)
    78      {
    79        /* separate alloc blocks, for malloc debugging */
    80        remp = TMP_ALLOC_LIMBS (vsize);
    81        tp = TMP_ALLOC_LIMBS (tsize);
    82        new_vp = NULL;
    83        if (rp == vp)
    84          new_vp = TMP_ALLOC_LIMBS (vsize);
    85      }
    86    else
    87      {
    88        /* one alloc with calculated size, for efficiency */
    89        mp_size_t size = vsize + tsize + (rp == vp ? vsize : 0);
    90        remp = TMP_ALLOC_LIMBS (size);
    91        tp = remp + vsize;
    92        new_vp = tp + tsize;
    93      }
    94  
    95    /* ensure divisor doesn't overlap quotient */
    96    if (rp == vp)
    97      {
    98        MPN_COPY (new_vp, vp, vsize);
    99        vp = new_vp;
   100      }
   101  
   102    MPN_ZERO (tp, tsize-1);
   103  
   104    tp[tsize - 1] = u & GMP_NUMB_MASK;
   105  #if BITS_PER_ULONG > GMP_NUMB_BITS
   106    if (u > GMP_NUMB_MAX)
   107      {
   108        /* tsize-vsize+1 == rsize, so tsize >= rsize.  rsize == prec+1 >= 2,
   109           so tsize >= 2, hence there's room for 2-limb u with nails */
   110        ASSERT (tsize >= 2);
   111        tp[tsize - 1] = u >> GMP_NUMB_BITS;
   112        tp[tsize - 2] = u & GMP_NUMB_MASK;
   113        rexp++;
   114      }
   115  #endif
   116  
   117    ASSERT (tsize-vsize+1 == rsize);
   118    mpn_tdiv_qr (rp, remp, (mp_size_t) 0, tp, tsize, vp, vsize);
   119  
   120    /* strip possible zero high limb */
   121    high_zero = (rp[rsize-1] == 0);
   122    rsize -= high_zero;
   123    rexp -= high_zero;
   124  
   125    r->_mp_size = sign_quotient >= 0 ? rsize : -rsize;
   126    r->_mp_exp = rexp;
   127    TMP_FREE;
   128  }