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Annotation of OpenXM_contrib/gmp/mpn/generic/sizeinbase.c, Revision 1.1.1.1

1.1       ohara       1: /* mpn_sizeinbase -- approximation to chars required for an mpn.
                      2:
                      3:    THE FUNCTIONS IN THIS FILE ARE FOR INTERNAL USE ONLY.  THEY'RE ALMOST
                      4:    CERTAIN TO BE SUBJECT TO INCOMPATIBLE CHANGES OR DISAPPEAR COMPLETELY IN
                      5:    FUTURE GNU MP RELEASES.
                      6:
                      7: Copyright 1991, 1993, 1994, 1995, 2001, 2002 Free Software Foundation, Inc.
                      8:
                      9: This file is part of the GNU MP Library.
                     10:
                     11: The GNU MP Library is free software; you can redistribute it and/or modify
                     12: it under the terms of the GNU Lesser General Public License as published by
                     13: the Free Software Foundation; either version 2.1 of the License, or (at your
                     14: option) any later version.
                     15:
                     16: The GNU MP Library is distributed in the hope that it will be useful, but
                     17: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
                     18: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
                     19: License for more details.
                     20:
                     21: You should have received a copy of the GNU Lesser General Public License
                     22: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
                     23: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     24: MA 02111-1307, USA. */
                     25:
                     26: #include "gmp.h"
                     27: #include "gmp-impl.h"
                     28: #include "longlong.h"
                     29:
                     30:
                     31: /* Same as mpz_sizeinbase, meaning exact for power-of-2 bases, and either
                     32:    exact or 1 too big for other bases.  */
                     33:
                     34: size_t
                     35: mpn_sizeinbase (mp_srcptr xp, mp_size_t xsize, int base)
                     36: {
                     37:   int lb_base, cnt;
                     38:   mp_size_t totbits;
                     39:
                     40:   ASSERT (xsize >= 0);
                     41:   ASSERT (base >= 2);
                     42:   ASSERT (base < numberof (__mp_bases));
                     43:
                     44:   /* Special case for X == 0.  */
                     45:   if (xsize == 0)
                     46:     return 1;
                     47:
                     48:   /* Calculate the total number of significant bits of X.  */
                     49:   count_leading_zeros (cnt, xp[xsize-1]);
                     50:   totbits = xsize * BITS_PER_MP_LIMB - cnt;
                     51:
                     52:   if (POW2_P (base))
                     53:     {
                     54:       /* Special case for powers of 2, giving exact result.  */
                     55:       lb_base = __mp_bases[base].big_base;
                     56:       return (totbits + lb_base - 1) / lb_base;
                     57:     }
                     58:   else
                     59:     return (size_t) (totbits * __mp_bases[base].chars_per_bit_exactly) + 1;
                     60: }