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: }
FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>