source/libs/gmp/gmp-src/mpz/aors.h

   1 /* mpz_add, mpz_sub -- add or subtract integers.
   2
   3 Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2011, 2012 Free Software
   4 Foundation, Inc.
   5
   6 This file is part of the GNU MP Library.
   7
   8 The GNU MP Library is free software; you can redistribute it and/or modify
   9 it under the terms of either:
  10
  11   * the GNU Lesser General Public License as published by the Free
  12     Software Foundation; either version 3 of the License, or (at your
  13     option) any later version.
  14
  15 or
  16
  17   * the GNU General Public License as published by the Free Software
  18     Foundation; either version 2 of the License, or (at your option) any
  19     later version.
  20
  21 or both in parallel, as here.
  22
  23 The GNU MP Library is distributed in the hope that it will be useful, but
  24 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  25 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  26 for more details.
  27
  28 You should have received copies of the GNU General Public License and the
  29 GNU Lesser General Public License along with the GNU MP Library.  If not,
  30 see https://www.gnu.org/licenses/.  */
  31
  32 #include "gmp.h"
  33 #include "gmp-impl.h"
  34
  35
  36 #ifdef OPERATION_add
  37 #define FUNCTION     mpz_add
  38 #define VARIATION
  39 #endif
  40 #ifdef OPERATION_sub
  41 #define FUNCTION     mpz_sub
  42 #define VARIATION    -
  43 #endif
  44
  45 #ifndef FUNCTION
  46 Error, need OPERATION_add or OPERATION_sub
  47 #endif
  48
  49
  50 void
  51 FUNCTION (mpz_ptr w, mpz_srcptr u, mpz_srcptr v)
  52 {
  53   mp_srcptr up, vp;
  54   mp_ptr wp;
  55   mp_size_t usize, vsize, wsize;
  56   mp_size_t abs_usize;
  57   mp_size_t abs_vsize;
  58
  59   usize = SIZ(u);
  60   vsize = VARIATION SIZ(v);
  61   abs_usize = ABS (usize);
  62   abs_vsize = ABS (vsize);
  63
  64   if (abs_usize < abs_vsize)
  65     {
  66       /* Swap U and V. */
  67       MPZ_SRCPTR_SWAP (u, v);
  68       MP_SIZE_T_SWAP (usize, vsize);
  69       MP_SIZE_T_SWAP (abs_usize, abs_vsize);
  70     }
  71
  72   /* True: ABS_USIZE >= ABS_VSIZE.  */
  73
  74   /* If not space for w (and possible carry), increase space.  */
  75   wsize = abs_usize + 1;
  76   wp = MPZ_REALLOC (w, wsize);
  77
  78   /* These must be after realloc (u or v may be the same as w).  */
  79   up = PTR(u);
  80   vp = PTR(v);
  81
  82   if ((usize ^ vsize) < 0)
  83     {
  84       /* U and V have different sign.  Need to compare them to determine
  85          which operand to subtract from which.  */
  86
  87       /* This test is right since ABS_USIZE >= ABS_VSIZE.  */
  88       if (abs_usize != abs_vsize)
  89         {
  90           mpn_sub (wp, up, abs_usize, vp, abs_vsize);
  91           wsize = abs_usize;
  92           MPN_NORMALIZE (wp, wsize);
  93           if (usize < 0)
  94             wsize = -wsize;
  95         }
  96       else if (mpn_cmp (up, vp, abs_usize) < 0)
  97         {
  98           mpn_sub_n (wp, vp, up, abs_usize);
  99           wsize = abs_usize;
 100           MPN_NORMALIZE (wp, wsize);
 101           if (usize >= 0)
 102             wsize = -wsize;
 103         }
 104       else
 105         {
 106           mpn_sub_n (wp, up, vp, abs_usize);
 107           wsize = abs_usize;
 108           MPN_NORMALIZE (wp, wsize);
 109           if (usize < 0)
 110             wsize = -wsize;
 111         }
 112     }
 113   else
 114     {
 115       /* U and V have same sign.  Add them.  */
 116       mp_limb_t cy_limb = mpn_add (wp, up, abs_usize, vp, abs_vsize);
 117       wp[abs_usize] = cy_limb;
 118       wsize = abs_usize + cy_limb;
 119       if (usize < 0)
 120         wsize = -wsize;
 121     }
 122
 123   SIZ(w) = wsize;
 124 }