macssh/gmp/mpz/inp_str.c

/* mpz_inp_str(dest_integer, stream, base) -- Input a number in base
   BASE from stdio stream STREAM and store the result in DEST_INTEGER.

Copyright (C) 1991, 1993, 1994, 1996, 1998, 2000 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 Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, 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 Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */

#include <stdio.h>
#include <ctype.h>
#include "gmp.h"
#include "gmp-impl.h"

static int
#if __STDC__
digit_value_in_base (int c, int base)
#else
digit_value_in_base (c, base)
     int c;
     int base;
#endif
{
  int digit;

  if (isdigit (c))
    digit = c - '0';
  else if (islower (c))
    digit = c - 'a' + 10;
  else if (isupper (c))
    digit = c - 'A' + 10;
  else
    return -1;

  if (digit < base)
    return digit;
  return -1;
}

size_t
#if __STDC__
mpz_inp_str (mpz_ptr x, FILE *stream, int base)
#else
mpz_inp_str (x, stream, base)
     mpz_ptr x;
     FILE *stream;
     int base;
#endif
{
  char *str;
  size_t alloc_size, str_size;
  int c;
  int negative;
  mp_size_t xsize;
  size_t nread;

  if (stream == 0)
    stream = stdin;

  nread = 0;

  /* Skip whitespace.  */
  do
    {
      c = getc (stream);
      nread++;
    }
  while (isspace (c));

  negative = 0;
  if (c == '-')
    {
      negative = 1;
      c = getc (stream);
      nread++;
    }

  if (digit_value_in_base (c, base == 0 ? 10 : base) < 0)
    return 0;			/* error if no digits */

  /* If BASE is 0, try to find out the base by looking at the initial
     characters.  */
  if (base == 0)
    {
      base = 10;
      if (c == '0')
	{
	  base = 8;
	  c = getc (stream);
	  nread++;
	  if (c == 'x' || c == 'X')
	    {
	      base = 16;
	      c = getc (stream);
	      nread++;
	    }
	  else if (c == 'b' || c == 'B')
	    {
	      base = 2;
	      c = getc (stream);
	      nread++;
	    }
	}
    }

  /* Skip leading zeros.  */
  while (c == '0')
    {
      c = getc (stream);
      nread++;
    }

  alloc_size = 100;
  str = (char *) (*_mp_allocate_func) (alloc_size);
  str_size = 0;

  for (;;)
    {
      int dig;
      if (str_size >= alloc_size)
	{
	  size_t old_alloc_size = alloc_size;
	  alloc_size = alloc_size * 3 / 2;
	  str = (char *) (*_mp_reallocate_func) (str, old_alloc_size, alloc_size);
	}
      dig = digit_value_in_base (c, base);
      if (dig < 0)
	break;
      str[str_size++] = dig;
      c = getc (stream);
    }

  ungetc (c, stream);

  /* Make sure the string is not empty, mpn_set_str would fail.  */
  if (str_size == 0)
    {
      x->_mp_size = 0;
      (*_mp_free_func) (str, alloc_size);
      return nread;
    }

  xsize = (((mp_size_t) (str_size / __mp_bases[base].chars_per_bit_exactly))
	   / BITS_PER_MP_LIMB + 2);
  if (x->_mp_alloc < xsize)
    _mpz_realloc (x, xsize);

  /* Convert the byte array in base BASE to our bignum format.  */
  xsize = mpn_set_str (x->_mp_d, (unsigned char *) str, str_size, base);
  x->_mp_size = negative ? -xsize : xsize;

  (*_mp_free_func) (str, alloc_size);
  return str_size + nread;
}