contrib/gmp/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, 2000, 2001, 2002, 2004 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 the GNU Lesser General Public License as published by
  11 the Free Software Foundation; either version 3 of the License, or (at your
  12 option) any later version.
  13
  14 The GNU MP Library is distributed in the hope that it will be useful, but
  15 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  16 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  17 License for more details.
  18
  19 You should have received a copy of the GNU Lesser General Public License
  20 along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
  21
  22 #include "gmp.h"
  23 #include "gmp-impl.h"
  24
  25
  26 #ifdef OPERATION_add_ui
  27 #define FUNCTION          mpz_add_ui
  28 #define FUNCTION2         mpz_add
  29 #define VARIATION_CMP     >=
  30 #define VARIATION_NEG
  31 #define VARIATION_UNNEG   -
  32 #endif
  33
  34 #ifdef OPERATION_sub_ui
  35 #define FUNCTION          mpz_sub_ui
  36 #define FUNCTION2         mpz_sub
  37 #define VARIATION_CMP     <
  38 #define VARIATION_NEG     -
  39 #define VARIATION_UNNEG
  40 #endif
  41
  42 #ifndef FUNCTION
  43 Error, need OPERATION_add_ui or OPERATION_sub_ui
  44 #endif
  45
  46
  47 void
  48 FUNCTION (mpz_ptr w, mpz_srcptr u, unsigned long int vval)
  49 {
  50   mp_srcptr up;
  51   mp_ptr wp;
  52   mp_size_t usize, wsize;
  53   mp_size_t abs_usize;
  54
  55 #if BITS_PER_ULONG > GMP_NUMB_BITS  /* avoid warnings about shift amount */
  56   if (vval > GMP_NUMB_MAX)
  57     {
  58       mpz_t v;
  59       mp_limb_t vl[2];
  60       PTR(v) = vl;
  61       vl[0] = vval & GMP_NUMB_MASK;
  62       vl[1] = vval >> GMP_NUMB_BITS;
  63       SIZ(v) = 2;
  64       FUNCTION2 (w, u, v);
  65       return;
  66     }
  67 #endif
  68
  69   usize = u->_mp_size;
  70   abs_usize = ABS (usize);
  71
  72   /* If not space for W (and possible carry), increase space.  */
  73   wsize = abs_usize + 1;
  74   if (w->_mp_alloc < wsize)
  75     _mpz_realloc (w, wsize);
  76
  77   /* These must be after realloc (U may be the same as W).  */
  78   up = u->_mp_d;
  79   wp = w->_mp_d;
  80
  81   if (abs_usize == 0)
  82     {
  83       wp[0] = vval;
  84       w->_mp_size = VARIATION_NEG (vval != 0);
  85       return;
  86     }
  87
  88   if (usize VARIATION_CMP 0)
  89     {
  90       mp_limb_t cy;
  91       cy = mpn_add_1 (wp, up, abs_usize, (mp_limb_t) vval);
  92       wp[abs_usize] = cy;
  93       wsize = VARIATION_NEG (abs_usize + cy);
  94     }
  95   else
  96     {
  97       /* The signs are different.  Need exact comparison to determine
  98          which operand to subtract from which.  */
  99       if (abs_usize == 1 && up[0] < vval)
 100         {
 101           wp[0] = vval - up[0];
 102           wsize = VARIATION_NEG 1;
 103         }
 104       else
 105         {
 106           mpn_sub_1 (wp, up, abs_usize, (mp_limb_t) vval);
 107           /* Size can decrease with at most one limb.  */
 108           wsize = VARIATION_UNNEG (abs_usize - (wp[abs_usize - 1] == 0));
 109         }
 110     }
 111
 112   w->_mp_size = wsize;
 113 }