source/libs/gmp/gmp-src/mpf/add_ui.c

   1 /* mpf_add_ui -- Add a float and an unsigned integer.
   2
   3 Copyright 1993, 1994, 1996, 2000, 2001 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.h"
  32 #include "gmp-impl.h"
  33
  34 void
  35 mpf_add_ui (mpf_ptr sum, mpf_srcptr u, unsigned long int v)
  36 {
  37   mp_srcptr up = u->_mp_d;
  38   mp_ptr sump = sum->_mp_d;
  39   mp_size_t usize, sumsize;
  40   mp_size_t prec = sum->_mp_prec;
  41   mp_exp_t uexp = u->_mp_exp;
  42
  43   usize = u->_mp_size;
  44   if (usize <= 0)
  45     {
  46       if (usize == 0)
  47         {
  48           mpf_set_ui (sum, v);
  49           return;
  50         }
  51       else
  52         {
  53           __mpf_struct u_negated;
  54           u_negated._mp_size = -usize;
  55           u_negated._mp_exp = u->_mp_exp;
  56           u_negated._mp_d = u->_mp_d;
  57           mpf_sub_ui (sum, &u_negated, v);
  58           sum->_mp_size = -(sum->_mp_size);
  59           return;
  60         }
  61     }
  62
  63   if (v == 0)
  64     {
  65     sum_is_u:
  66       if (u != sum)
  67         {
  68           sumsize = MIN (usize, prec + 1);
  69           MPN_COPY (sum->_mp_d, up + usize - sumsize, sumsize);
  70           sum->_mp_size = sumsize;
  71           sum->_mp_exp = u->_mp_exp;
  72         }
  73       return;
  74     }
  75
  76   if (uexp > 0)
  77     {
  78       /* U >= 1.  */
  79       if (uexp > prec)
  80         {
  81           /* U >> V, V is not part of final result.  */
  82           goto sum_is_u;
  83         }
  84       else
  85         {
  86           /* U's "limb point" is somewhere between the first limb
  87              and the PREC:th limb.
  88              Both U and V are part of the final result.  */
  89           if (uexp > usize)
  90             {
  91               /*   uuuuuu0000. */
  92               /* +          v. */
  93               /* We begin with moving U to the top of SUM, to handle
  94                  samevar(U,SUM).  */
  95               MPN_COPY_DECR (sump + uexp - usize, up, usize);
  96               sump[0] = v;
  97               MPN_ZERO (sump + 1, uexp - usize - 1);
  98 #if 0 /* What is this??? */
  99               if (sum == u)
 100                 MPN_COPY (sum->_mp_d, sump, uexp);
 101 #endif
 102               sum->_mp_size = uexp;
 103               sum->_mp_exp = uexp;
 104             }
 105           else
 106             {
 107               /*   uuuuuu.uuuu */
 108               /* +      v.     */
 109               mp_limb_t cy_limb;
 110               if (usize > prec)
 111                 {
 112                   /* Ignore excess limbs in U.  */
 113                   up += usize - prec;
 114                   usize -= usize - prec; /* Eq. usize = prec */
 115                 }
 116               if (sump != up)
 117                 MPN_COPY_INCR (sump, up, usize - uexp);
 118               cy_limb = mpn_add_1 (sump + usize - uexp, up + usize - uexp,
 119                                    uexp, (mp_limb_t) v);
 120               sump[usize] = cy_limb;
 121               sum->_mp_size = usize + cy_limb;
 122               sum->_mp_exp = uexp + cy_limb;
 123             }
 124         }
 125     }
 126   else
 127     {
 128       /* U < 1, so V > U for sure.  */
 129       /* v.         */
 130       /*  .0000uuuu */
 131       if ((-uexp) >= prec)
 132         {
 133           sump[0] = v;
 134           sum->_mp_size = 1;
 135           sum->_mp_exp = 1;
 136         }
 137       else
 138         {
 139           if (usize + (-uexp) + 1 > prec)
 140             {
 141               /* Ignore excess limbs in U.  */
 142               up += usize + (-uexp) + 1 - prec;
 143               usize -= usize + (-uexp) + 1 - prec;
 144             }
 145           if (sump != up)
 146             MPN_COPY_INCR (sump, up, usize);
 147           MPN_ZERO (sump + usize, -uexp);
 148           sump[usize + (-uexp)] = v;
 149           sum->_mp_size = usize + (-uexp) + 1;
 150           sum->_mp_exp = 1;
 151         }
 152     }
 153 }