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Annotation of OpenXM_contrib/gmp/mpz/tdiv_r_2exp.c, Revision 1.1.1.3

1.1       maekawa     1: /* mpz_tdiv_r_2exp -- Divide a integer by 2**CNT and produce a remainder.
                      2:
1.1.1.3 ! ohara       3: Copyright 1991, 1993, 1994, 1995, 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_tdiv_r_2exp (mpz_ptr res, mpz_srcptr in, unsigned long int cnt)
                     27: {
                     28:   mp_size_t in_size = ABS (in->_mp_size);
                     29:   mp_size_t res_size;
1.1.1.3 ! ohara      30:   mp_size_t limb_cnt = cnt / GMP_NUMB_BITS;
1.1       maekawa    31:   mp_srcptr in_ptr = in->_mp_d;
                     32:
                     33:   if (in_size > limb_cnt)
                     34:     {
                     35:       /* The input operand is (probably) greater than 2**CNT.  */
                     36:       mp_limb_t x;
                     37:
1.1.1.3 ! ohara      38:       x = in_ptr[limb_cnt] & (((mp_limb_t) 1 << cnt % GMP_NUMB_BITS) - 1);
1.1       maekawa    39:       if (x != 0)
                     40:        {
                     41:          res_size = limb_cnt + 1;
                     42:          if (res->_mp_alloc < res_size)
                     43:            _mpz_realloc (res, res_size);
                     44:
                     45:          res->_mp_d[limb_cnt] = x;
                     46:        }
                     47:       else
                     48:        {
                     49:          res_size = limb_cnt;
                     50:          MPN_NORMALIZE (in_ptr, res_size);
                     51:
                     52:          if (res->_mp_alloc < res_size)
                     53:            _mpz_realloc (res, res_size);
                     54:
                     55:          limb_cnt = res_size;
                     56:        }
                     57:     }
                     58:   else
                     59:     {
                     60:       /* The input operand is smaller than 2**CNT.  We perform a no-op,
                     61:         apart from that we might need to copy IN to RES.  */
                     62:       res_size = in_size;
                     63:       if (res->_mp_alloc < res_size)
                     64:        _mpz_realloc (res, res_size);
                     65:
                     66:       limb_cnt = res_size;
                     67:     }
                     68:
                     69:   if (res != in)
                     70:     MPN_COPY (res->_mp_d, in->_mp_d, limb_cnt);
                     71:   res->_mp_size = in->_mp_size >= 0 ? res_size : -res_size;
                     72: }