path: root/mpf/set_str.c

/* mpf_set_str (dest, string, base) -- Convert the string STRING
   in base BASE to a float in dest.  If BASE is zero, the leading characters
   of STRING is used to figure out the base.

Copyright 1993-1997, 2000-2003, 2005, 2007, 2008, 2011, 2013 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 3 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.  If not, see https://www.gnu.org/licenses/.  */

/*
  This still needs work, as suggested by some FIXME comments.
  1. Don't depend on superfluous mantissa digits.
  2. Allocate temp space more cleverly.
  3. Use mpn_div_q instead of mpn_lshift+mpn_divrem.
*/

#define _GNU_SOURCE    /* for DECIMAL_POINT in langinfo.h */

#include "config.h"

#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#if HAVE_LANGINFO_H
#include <langinfo.h>  /* for nl_langinfo */
#endif

#if HAVE_LOCALE_H
#include <locale.h>    /* for localeconv */
#endif

#include "gmp.h"
#include "gmp-impl.h"
#include "longlong.h"


#define digit_value_tab __gmp_digit_value_tab

/* Compute base^exp and return the most significant prec limbs in rp[].
   Put the count of omitted low limbs in *ign.
   Return the actual size (which might be less than prec).  */
static mp_size_t
mpn_pow_1_highpart (mp_ptr rp, mp_size_t *ignp,
		    mp_limb_t base, mp_exp_t exp,
		    mp_size_t prec, mp_ptr tp)
{
  mp_size_t ign;		/* counts number of ignored low limbs in r */
  mp_size_t off;		/* keeps track of offset where value starts */
  mp_ptr passed_rp = rp;
  mp_size_t rn;
  int cnt;
  int i;

  rp[0] = base;
  rn = 1;
  off = 0;
  ign = 0;
  count_leading_zeros (cnt, exp);
  for (i = GMP_LIMB_BITS - cnt - 2; i >= 0; i--)
    {
      mpn_sqr (tp, rp + off, rn);
      rn = 2 * rn;
      rn -= tp[rn - 1] == 0;
      ign <<= 1;

      off = 0;
      if (rn > prec)
	{
	  ign += rn - prec;
	  off = rn - prec;
	  rn = prec;
	}
      MP_PTR_SWAP (rp, tp);

      if (((exp >> i) & 1) != 0)
	{
	  mp_limb_t cy;
	  cy = mpn_mul_1 (rp, rp + off, rn, base);
	  rp[rn] = cy;
	  rn += cy != 0;
	  off = 0;
	}
    }

  if (rn > prec)
    {
      ign += rn - prec;
      rp += rn - prec;
      rn = prec;
    }

  MPN_COPY_INCR (passed_rp, rp + off, rn);
  *ignp = ign;
  return rn;
}

int
mpf_set_str (mpf_ptr x, const char *str, int base)
{
  size_t str_size;
  char *s, *begs;
  size_t i, j;
  int c;
  int negative;
  char *dotpos = 0;
  const char *expptr;
  int exp_base;
  const char  *point = GMP_DECIMAL_POINT;
  size_t      pointlen = strlen (point);
  const unsigned char *digit_value;
  TMP_DECL;

  c = (unsigned char) *str;

  /* Skip whitespace.  */
  while (isspace (c))
    c = (unsigned char) *++str;

  negative = 0;
  if (c == '-')
    {
      negative = 1;
      c = (unsigned char) *++str;
    }

  /* Default base to decimal.  */
  if (base == 0)
    base = 10;

  exp_base = base;

  if (base < 0)
    {
      exp_base = 10;
      base = -base;
    }

  digit_value = digit_value_tab;
  if (base > 36)
    {
      /* For bases > 36, use the collating sequence
	 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz.  */
      digit_value += 208;
      if (base > 62)
	return -1;		/* too large base */
    }

  /* Require at least one digit, possibly after an initial decimal point.  */
  if (digit_value[c] >= base)
    {
      /* not a digit, must be a decimal point */
      for (i = 0; i < pointlen; i++)
	if (str[i] != point[i])
	  return -1;
      if (digit_value[(unsigned char) str[pointlen]] >= base)
	return -1;
    }

  /* Locate exponent part of the input.  Look from the right of the string,
     since the exponent is usually a lot shorter than the mantissa.  */
  expptr = NULL;
  str_size = strlen (str);
  for (i = str_size - 1; i > 0; i--)
    {
      c = (unsigned char) str[i];
      if (c == '@' || (base <= 10 && (c == 'e' || c == 'E')))
	{
	  expptr = str + i + 1;
	  str_size = i;
	  break;
	}
    }

  TMP_MARK;
  s = begs = (char *) TMP_ALLOC (str_size + 1);

  /* Loop through mantissa, converting it from ASCII to raw byte values.  */
  for (i = 0; i < str_size; i++)
    {
      c = (unsigned char) *str;
      if (!isspace (c))
	{
	  int dig;

	  for (j = 0; j < pointlen; j++)
	    if (str[j] != point[j])
	      goto not_point;
	  if (1)
	    {
	      if (dotpos != 0)
		{
		  /* already saw a decimal point, another is invalid */
		  TMP_FREE;
		  return -1;
		}
	      dotpos = s;
	      str += pointlen - 1;
	      i += pointlen - 1;
	    }
	  else
	    {
	    not_point:
	      dig = digit_value[c];
	      if (dig >= base)
		{
		  TMP_FREE;
		  return -1;
		}
	      *s++ = dig;
	    }
	}
      c = (unsigned char) *++str;
    }

  str_size = s - begs;

  {
    long exp_in_base;
    mp_size_t ra, ma, rn, mn;
    int cnt;
    mp_ptr mp, tp, rp;
    mp_exp_t exp_in_limbs;
    mp_size_t prec = PREC(x) + 1;
    int divflag;
    mp_size_t madj, radj;

#if 0
    size_t n_chars_needed;

    /* This breaks things like 0.000...0001.  To safely ignore superfluous
       digits, we need to skip over leading zeros.  */
    /* Just consider the relevant leading digits of the mantissa.  */
    LIMBS_PER_DIGIT_IN_BASE (n_chars_needed, prec, base);
    if (str_size > n_chars_needed)
      str_size = n_chars_needed;
#endif

    LIMBS_PER_DIGIT_IN_BASE (ma, str_size, base);
    mp = TMP_ALLOC_LIMBS (ma);
    mn = mpn_set_str (mp, (unsigned char *) begs, str_size, base);

    if (mn == 0)
      {
	SIZ(x) = 0;
	EXP(x) = 0;
	TMP_FREE;
	return 0;
      }

    madj = 0;
    /* Ignore excess limbs in MP,MSIZE.  */
    if (mn > prec)
      {
	madj = mn - prec;
	mp += mn - prec;
	mn = prec;
      }

    if (expptr != 0)
      {
	/* Scan and convert the exponent, in base exp_base.  */
	long dig, minus, plusminus;
	c = (unsigned char) *expptr;
	minus = -(long) (c == '-');
	plusminus = minus | -(long) (c == '+');
	expptr -= plusminus;			/* conditional increment */
	c = (unsigned char) *expptr++;
	dig = digit_value[c];
	if (dig >= exp_base)
	  {
	    TMP_FREE;
	    return -1;
	  }
	exp_in_base = dig;
	c = (unsigned char) *expptr++;
	dig = digit_value[c];
	while (dig < exp_base)
	  {
	    exp_in_base = exp_in_base * exp_base;
	    exp_in_base += dig;
	    c = (unsigned char) *expptr++;
	    dig = digit_value[c];
	  }
	exp_in_base = (exp_in_base ^ minus) - minus; /* conditional negation */
      }
    else
      exp_in_base = 0;
    if (dotpos != 0)
      exp_in_base -= s - dotpos;
    divflag = exp_in_base < 0;
    exp_in_base = ABS (exp_in_base);

    if (exp_in_base == 0)
      {
	MPN_COPY (PTR(x), mp, mn);
	SIZ(x) = negative ? -mn : mn;
	EXP(x) = mn + madj;
	TMP_FREE;
	return 0;
      }

    ra = 2 * (prec + 1);
    rp = TMP_ALLOC_LIMBS (ra);
    tp = TMP_ALLOC_LIMBS (ra);
    rn = mpn_pow_1_highpart (rp, &radj, (mp_limb_t) base, exp_in_base, prec, tp);

    if (divflag)
      {
#if 0
	/* FIXME: Should use mpn_div_q here.  */
	...
	mpn_div_q (tp, mp, mn, rp, rn, scratch);
	...
#else
	mp_ptr qp;
	mp_limb_t qlimb;
	if (mn < rn)
	  {
	    /* Pad out MP,MSIZE for current divrem semantics.  */
	    mp_ptr tmp = TMP_ALLOC_LIMBS (rn + 1);
	    MPN_ZERO (tmp, rn - mn);
	    MPN_COPY (tmp + rn - mn, mp, mn);
	    mp = tmp;
	    madj -= rn - mn;
	    mn = rn;
	  }
	if ((rp[rn - 1] & GMP_NUMB_HIGHBIT) == 0)
	  {
	    mp_limb_t cy;
	    count_leading_zeros (cnt, rp[rn - 1]);
	    cnt -= GMP_NAIL_BITS;
	    mpn_lshift (rp, rp, rn, cnt);
	    cy = mpn_lshift (mp, mp, mn, cnt);
	    if (cy)
	      mp[mn++] = cy;
	  }

	qp = TMP_ALLOC_LIMBS (prec + 1);
	qlimb = mpn_divrem (qp, prec - (mn - rn), mp, mn, rp, rn);
	tp = qp;
	exp_in_limbs = qlimb + (mn - rn) + (madj - radj);
	rn = prec;
	if (qlimb != 0)
	  {
	    tp[prec] = qlimb;
	    /* Skip the least significant limb not to overrun the destination
	       variable.  */
	    tp++;
	  }
#endif
      }
    else
      {
	tp = TMP_ALLOC_LIMBS (rn + mn);
	if (rn > mn)
	  mpn_mul (tp, rp, rn, mp, mn);
	else
	  mpn_mul (tp, mp, mn, rp, rn);
	rn += mn;
	rn -= tp[rn - 1] == 0;
	exp_in_limbs = rn + madj + radj;

	if (rn > prec)
	  {
	    tp += rn - prec;
	    rn = prec;
	    exp_in_limbs += 0;
	  }
      }

    MPN_COPY (PTR(x), tp, rn);
    SIZ(x) = negative ? -rn : rn;
    EXP(x) = exp_in_limbs;
    TMP_FREE;
    return 0;
  }
}