/* mpz_add_ui -- Add an mpz_t and an unsigned one-word integer.
Copyright (C) 1991, 1993, 1994, 1996 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at your
option) any later version.
The GNU MP Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
License for more details.
You should have received a copy of the GNU Library General Public License
along with the GNU MP Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include "gmp.h"
#include "gmp-impl.h"
void
#if __STDC__
mpz_add_ui (mpz_ptr w, mpz_srcptr u, unsigned long int v)
#else
mpz_add_ui (w, u, v)
mpz_ptr w;
mpz_srcptr u;
unsigned long int v;
#endif
{
mp_srcptr up;
mp_ptr wp;
mp_size_t usize, wsize;
mp_size_t abs_usize;
usize = u->_mp_size;
abs_usize = ABS (usize);
/* If not space for W (and possible carry), increase space. */
wsize = abs_usize + 1;
if (w->_mp_alloc < wsize)
_mpz_realloc (w, wsize);
/* These must be after realloc (U may be the same as W). */
up = u->_mp_d;
wp = w->_mp_d;
if (abs_usize == 0)
{
wp[0] = v;
w->_mp_size = v != 0;
return;
}
if (usize >= 0)
{
mp_limb_t cy;
cy = mpn_add_1 (wp, up, abs_usize, v);
wp[abs_usize] = cy;
wsize = abs_usize + cy;
}
else
{
/* The signs are different. Need exact comparison to determine
which operand to subtract from which. */
if (abs_usize == 1 && up[0] < v)
{
wp[0] = v - up[0];
wsize = 1;
}
else
{
mpn_sub_1 (wp, up, abs_usize, v);
/* Size can decrease with at most one limb. */
wsize = -(abs_usize - (wp[abs_usize - 1] == 0));
}
}
w->_mp_size = wsize;
}
