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Annotation of OpenXM_contrib/gmp/mpz/tdiv_r_2exp.c, Revision 1.1.1.2

1.1       maekawa     1: /* mpz_tdiv_r_2exp -- Divide a integer by 2**CNT and produce a remainder.
                      2:
                      3: Copyright (C) 1991, 1993, 1994, 1995 Free Software Foundation, Inc.
                      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: #if __STDC__
                     27: mpz_tdiv_r_2exp (mpz_ptr res, mpz_srcptr in, unsigned long int cnt)
                     28: #else
                     29: mpz_tdiv_r_2exp (res, in, cnt)
                     30:      mpz_ptr res;
                     31:      mpz_srcptr in;
                     32:      unsigned long int cnt;
                     33: #endif
                     34: {
                     35:   mp_size_t in_size = ABS (in->_mp_size);
                     36:   mp_size_t res_size;
                     37:   mp_size_t limb_cnt = cnt / BITS_PER_MP_LIMB;
                     38:   mp_srcptr in_ptr = in->_mp_d;
                     39:
                     40:   if (in_size > limb_cnt)
                     41:     {
                     42:       /* The input operand is (probably) greater than 2**CNT.  */
                     43:       mp_limb_t x;
                     44:
                     45:       x = in_ptr[limb_cnt] & (((mp_limb_t) 1 << cnt % BITS_PER_MP_LIMB) - 1);
                     46:       if (x != 0)
                     47:        {
                     48:          res_size = limb_cnt + 1;
                     49:          if (res->_mp_alloc < res_size)
                     50:            _mpz_realloc (res, res_size);
                     51:
                     52:          res->_mp_d[limb_cnt] = x;
                     53:        }
                     54:       else
                     55:        {
                     56:          res_size = limb_cnt;
                     57:          MPN_NORMALIZE (in_ptr, res_size);
                     58:
                     59:          if (res->_mp_alloc < res_size)
                     60:            _mpz_realloc (res, res_size);
                     61:
                     62:          limb_cnt = res_size;
                     63:        }
                     64:     }
                     65:   else
                     66:     {
                     67:       /* The input operand is smaller than 2**CNT.  We perform a no-op,
                     68:         apart from that we might need to copy IN to RES.  */
                     69:       res_size = in_size;
                     70:       if (res->_mp_alloc < res_size)
                     71:        _mpz_realloc (res, res_size);
                     72:
                     73:       limb_cnt = res_size;
                     74:     }
                     75:
                     76:   if (res != in)
                     77:     MPN_COPY (res->_mp_d, in->_mp_d, limb_cnt);
                     78:   res->_mp_size = in->_mp_size >= 0 ? res_size : -res_size;
                     79: }