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

   1 /* mpz_add_ui, mpz_sub_ui -- Add or subtract an mpz_t and an unsigned
   2    one-word integer.
   3
   4 Copyright 1991, 1993, 1994, 1996, 1999-2002, 2004, 2012, 2013 Free Software
   5 Foundation, Inc.
   6
   7 This file is part of the GNU MP Library.
   8
   9 The GNU MP Library is free software; you can redistribute it and/or modify
  10 it under the terms of either:
  11
  12   * the GNU Lesser General Public License as published by the Free
  13     Software Foundation; either version 3 of the License, or (at your
  14     option) any later version.
  15
  16 or
  17
  18   * the GNU General Public License as published by the Free Software
  19     Foundation; either version 2 of the License, or (at your option) any
  20     later version.
  21
  22 or both in parallel, as here.
  23
  24 The GNU MP Library is distributed in the hope that it will be useful, but
  25 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  26 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  27 for more details.
  28
  29 You should have received copies of the GNU General Public License and the
  30 GNU Lesser General Public License along with the GNU MP Library.  If not,
  31 see https://www.gnu.org/licenses/.  */
  32
  33 #include "gmp.h"
  34 #include "gmp-impl.h"
  35
  36
  37 #ifdef OPERATION_add_ui
  38 #define FUNCTION          mpz_add_ui
  39 #define FUNCTION2         mpz_add
  40 #define VARIATION_CMP     >=
  41 #define VARIATION_NEG
  42 #define VARIATION_UNNEG   -
  43 #endif
  44
  45 #ifdef OPERATION_sub_ui
  46 #define FUNCTION          mpz_sub_ui
  47 #define FUNCTION2         mpz_sub
  48 #define VARIATION_CMP     <
  49 #define VARIATION_NEG     -
  50 #define VARIATION_UNNEG
  51 #endif
  52
  53 #ifndef FUNCTION
  54 Error, need OPERATION_add_ui or OPERATION_sub_ui
  55 #endif
  56
  57
  58 void
  59 FUNCTION (mpz_ptr w, mpz_srcptr u, unsigned long int vval)
  60 {
  61   mp_srcptr up;
  62   mp_ptr wp;
  63   mp_size_t usize, wsize;
  64   mp_size_t abs_usize;
  65
  66 #if BITS_PER_ULONG > GMP_NUMB_BITS  /* avoid warnings about shift amount */
  67   if (vval > GMP_NUMB_MAX)
  68     {
  69       mpz_t v;
  70       mp_limb_t vl[2];
  71       PTR(v) = vl;
  72       vl[0] = vval & GMP_NUMB_MASK;
  73       vl[1] = vval >> GMP_NUMB_BITS;
  74       SIZ(v) = 2;
  75       FUNCTION2 (w, u, v);
  76       return;
  77     }
  78 #endif
  79
  80   usize = SIZ (u);
  81   if (usize == 0)
  82     {
  83       PTR (w)[0] = vval;
  84       SIZ (w) = VARIATION_NEG (vval != 0);
  85       return;
  86     }
  87
  88   abs_usize = ABS (usize);
  89
  90   /* If not space for W (and possible carry), increase space.  */
  91   wp = MPZ_REALLOC (w, abs_usize + 1);
  92
  93   /* These must be after realloc (U may be the same as W).  */
  94   up = PTR (u);
  95
  96   if (usize VARIATION_CMP 0)
  97     {
  98       mp_limb_t cy;
  99       cy = mpn_add_1 (wp, up, abs_usize, (mp_limb_t) vval);
 100       wp[abs_usize] = cy;
 101       wsize = VARIATION_NEG (abs_usize + cy);
 102     }
 103   else
 104     {
 105       /* The signs are different.  Need exact comparison to determine
 106          which operand to subtract from which.  */
 107       if (abs_usize == 1 && up[0] < vval)
 108         {
 109           wp[0] = vval - up[0];
 110           wsize = VARIATION_NEG 1;
 111         }
 112       else
 113         {
 114           mpn_sub_1 (wp, up, abs_usize, (mp_limb_t) vval);
 115           /* Size can decrease with at most one limb.  */
 116           wsize = VARIATION_UNNEG (abs_usize - (wp[abs_usize - 1] == 0));
 117         }
 118     }
 119
 120   SIZ (w) = wsize;
 121 }