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Annotation of OpenXM_contrib/gmp/mpz/mul_2exp.c, Revision 1.1.1.3

1.1       maekawa     1: /* mpz_mul_2exp -- Multiply a bignum by 2**CNT
                      2:
1.1.1.3 ! ohara       3: Copyright 1991, 1993, 1994, 1996, 2001, 2002 Free Software Foundation, Inc.
1.1       maekawa     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
1.1.1.2   maekawa     8: it under the terms of the GNU Lesser General Public License as published by
                      9: the Free Software Foundation; either version 2.1 of the License, or (at your
1.1       maekawa    10: option) any later version.
                     11:
                     12: The GNU MP Library is distributed in the hope that it will be useful, but
                     13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
1.1.1.2   maekawa    14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
1.1       maekawa    15: License for more details.
                     16:
1.1.1.2   maekawa    17: You should have received a copy of the GNU Lesser General Public License
1.1       maekawa    18: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
                     19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     20: MA 02111-1307, USA. */
                     21:
                     22: #include "gmp.h"
                     23: #include "gmp-impl.h"
                     24:
                     25: void
                     26: mpz_mul_2exp (mpz_ptr w, mpz_srcptr u, unsigned long int cnt)
                     27: {
                     28:   mp_size_t usize = u->_mp_size;
                     29:   mp_size_t abs_usize = ABS (usize);
                     30:   mp_size_t wsize;
                     31:   mp_size_t limb_cnt;
                     32:   mp_ptr wp;
                     33:   mp_limb_t wlimb;
                     34:
                     35:   if (usize == 0)
                     36:     {
                     37:       w->_mp_size = 0;
                     38:       return;
                     39:     }
                     40:
1.1.1.3 ! ohara      41:   limb_cnt = cnt / GMP_NUMB_BITS;
1.1       maekawa    42:   wsize = abs_usize + limb_cnt + 1;
                     43:   if (w->_mp_alloc < wsize)
                     44:     _mpz_realloc (w, wsize);
                     45:
                     46:   wp = w->_mp_d;
                     47:   wsize = abs_usize + limb_cnt;
                     48:
1.1.1.3 ! ohara      49:   cnt %= GMP_NUMB_BITS;
1.1       maekawa    50:   if (cnt != 0)
                     51:     {
                     52:       wlimb = mpn_lshift (wp + limb_cnt, u->_mp_d, abs_usize, cnt);
                     53:       if (wlimb != 0)
                     54:        {
                     55:          wp[wsize] = wlimb;
                     56:          wsize++;
                     57:        }
                     58:     }
                     59:   else
                     60:     {
                     61:       MPN_COPY_DECR (wp + limb_cnt, u->_mp_d, abs_usize);
                     62:     }
                     63:
                     64:   /* Zero all whole limbs at low end.  Do it here and not before calling
                     65:      mpn_lshift, not to lose for U == W.  */
                     66:   MPN_ZERO (wp, limb_cnt);
                     67:
                     68:   w->_mp_size = usize >= 0 ? wsize : -wsize;
                     69: }