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Annotation of OpenXM_contrib/gmp/mpz/sizeinbase.c, Revision 1.1

1.1     ! maekawa     1: /* mpz_sizeinbase(x, base) -- return an approximation to the number of
        !             2:    character the integer X would have printed in base BASE.  The
        !             3:    approximation is never too small.
        !             4:
        !             5: Copyright (C) 1991, 1993, 1994, 1995 Free Software Foundation, Inc.
        !             6:
        !             7: This file is part of the GNU MP Library.
        !             8:
        !             9: The GNU MP Library is free software; you can redistribute it and/or modify
        !            10: it under the terms of the GNU Library General Public License as published by
        !            11: the Free Software Foundation; either version 2 of the License, or (at your
        !            12: option) any later version.
        !            13:
        !            14: The GNU MP Library is distributed in the hope that it will be useful, but
        !            15: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            16: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
        !            17: License for more details.
        !            18:
        !            19: You should have received a copy of the GNU Library General Public License
        !            20: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
        !            21: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
        !            22: MA 02111-1307, USA. */
        !            23:
        !            24: #include "gmp.h"
        !            25: #include "gmp-impl.h"
        !            26: #include "longlong.h"
        !            27:
        !            28: size_t
        !            29: #if __STDC__
        !            30: mpz_sizeinbase (mpz_srcptr x, int base)
        !            31: #else
        !            32: mpz_sizeinbase (x, base)
        !            33:      mpz_srcptr x;
        !            34:      int base;
        !            35: #endif
        !            36: {
        !            37:   mp_size_t size = ABS (x->_mp_size);
        !            38:   int lb_base, cnt;
        !            39:   size_t totbits;
        !            40:
        !            41:   /* Special case for X == 0.  */
        !            42:   if (size == 0)
        !            43:     return 1;
        !            44:
        !            45:   /* Calculate the total number of significant bits of X.  */
        !            46:   count_leading_zeros (cnt, x->_mp_d[size - 1]);
        !            47:   totbits = size * BITS_PER_MP_LIMB - cnt;
        !            48:
        !            49:   if ((base & (base - 1)) == 0)
        !            50:     {
        !            51:       /* Special case for powers of 2, giving exact result.  */
        !            52:
        !            53:       count_leading_zeros (lb_base, base);
        !            54:       lb_base = BITS_PER_MP_LIMB - lb_base - 1;
        !            55:
        !            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: }