60 lines
1.7 KiB
C
60 lines
1.7 KiB
C
/* mpz_sizeinbase(x, base)  return an approximation to the number of


character the integer X would have printed in base BASE. The


approximation is never too small.




Copyright (C) 1991 Free Software Foundation, Inc.




This file is part of the GNU MP Library.




The GNU MP Library is free software; you can redistribute it and/or modify


it under the terms of the GNU General Public License as published by


the Free Software Foundation; either version 2, or (at your option)


any later version.




The GNU MP Library is distributed in the hope that it will be useful,


but WITHOUT ANY WARRANTY; without even the implied warranty of


MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the


GNU General Public License for more details.




You should have received a copy of the GNU General Public License


along with the GNU MP Library; see the file COPYING. If not, write to


the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */




#include "gmp.h"


#include "gmpimpl.h"


#include "longlong.h"




size_t


#ifdef __STDC__


mpz_sizeinbase (const MP_INT *x, int base)


#else


mpz_sizeinbase (x, base)


const MP_INT *x;


int base;


#endif


{


mp_size size = ABS (x>size);


int lb_base, cnt;


size_t totbits;




/* Special case for X == 0. */


if (size == 0)


return 1;




/* Calculate the total number of significant bits of X. */


count_leading_zeros (cnt, x>d[size  1]);


totbits = size * BITS_PER_MP_LIMB  cnt;




if ((base & (base  1)) == 0)


{


/* Special case for powers of 2, giving exact result. */




count_leading_zeros (lb_base, base);


lb_base = BITS_PER_MP_LIMB  lb_base  1;




return (totbits + lb_base  1) / lb_base;


}


else


return (size_t) (totbits * __mp_bases[base].chars_per_bit_exactly) + 1;


}
