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