/* Compatibility functions for floating point formatting, reentrant versions.

   Copyright (C) 1995-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C 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 C 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 C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <errno.h>

#include <float.h>

#include <stdio.h>

#include <string.h>

#include <ctype.h>

#include <math.h>

#include <stdlib.h>

#include <sys/param.h>

#include <math_ldbl_opt.h>

#ifndef FLOAT_TYPE

# define FLOAT_TYPE double

# define FUNC_PREFIX

# define FLOAT_FMT_FLAG

# define FLOAT_NAME_EXT

# define FLOAT_MIN_10_EXP DBL_MIN_10_EXP

# if DBL_MANT_DIG == 53

#  define NDIGIT_MAX 17

# elif DBL_MANT_DIG == 24

#  define NDIGIT_MAX 9

# elif DBL_MANT_DIG == 56

#  define NDIGIT_MAX 18

# else

/* See IEEE 854 5.6, table 2 for this formula.  Unfortunately we need a

   compile time constant here, so we cannot use it.  */

#  error "NDIGIT_MAX must be precomputed"

#  define NDIGIT_MAX (lrint (ceil (M_LN2 / M_LN10 * DBL_MANT_DIG + 1.0)))

# endif

# if DBL_MIN_10_EXP == -37

#  define FLOAT_MIN_10_NORM	1.0e-37

# elif DBL_MIN_10_EXP == -307

#  define FLOAT_MIN_10_NORM	1.0e-307

# elif DBL_MIN_10_EXP == -4931

#  define FLOAT_MIN_10_NORM	1.0e-4931

# else

/* libc can't depend on libm.  */

#  error "FLOAT_MIN_10_NORM must be precomputed"

#  define FLOAT_MIN_10_NORM	exp10 (DBL_MIN_10_EXP)

# endif

#else

# define LONG_DOUBLE_CVT

#endif

#define APPEND(a, b) APPEND2 (a, b)

#define APPEND2(a, b) a##b

#define __APPEND(a, b) __APPEND2 (a, b)

#define __APPEND2(a, b) __##a##b

#define FLOOR APPEND(floor, FLOAT_NAME_EXT)

#define FABS APPEND(fabs, FLOAT_NAME_EXT)

#define LOG10 APPEND(log10, FLOAT_NAME_EXT)

#define EXP APPEND(exp, FLOAT_NAME_EXT)

int

__APPEND (FUNC_PREFIX, fcvt_r) (FLOAT_TYPE value, int ndigit, int *decpt,

				int *sign, char *buf, size_t len)

{

  ssize_t n;

  ssize_t i;

  int left;

  if (buf == NULL)

    {

      __set_errno (EINVAL);

      return -1;

    }

  left = 0;

  if (isfinite (value))

    {

      *sign = signbit (value) != 0;

      if (*sign)

	value = -value;

      if (ndigit < 0)

	{

	  /* Rounding to the left of the decimal point.  */

	  while (ndigit < 0)

	    {

	      FLOAT_TYPE new_value = value * 0.1;

	      if (new_value < 1.0)

		{

		  ndigit = 0;

		  break;

		}

	      value = new_value;

	      ++left;

	      ++ndigit;

	    }

	}

    }

  else

    /* Value is Inf or NaN.  */

    *sign = 0;

  n = __snprintf (buf, len, "%.*" FLOAT_FMT_FLAG "f", MIN (ndigit, NDIGIT_MAX),

		  value);

  /* Check for a too small buffer.  */

  if (n >= (ssize_t) len)

    return -1;

  i = 0;

  while (i < n && isdigit (buf[i]))

    ++i;

  *decpt = i;

  if (i == 0)

    /* Value is Inf or NaN.  */

    return 0;

  if (i < n)

    {

      do

	++i;

      while (i < n && !isdigit (buf[i]));

      if (*decpt == 1 && buf[0] == '0' && value != 0.0)

	{

	  /* We must not have leading zeroes.  Strip them all out and

	     adjust *DECPT if necessary.  */

	  --*decpt;

	  while (i < n && buf[i] == '0')

	    {

	      --*decpt;

	      ++i;

	    }

	}

      memmove (&buf[MAX (*decpt, 0)], &buf[i], n - i);

      buf[n - (i - MAX (*decpt, 0))] = '\0';

    }

  if (left)

    {

      *decpt += left;

      if ((ssize_t) --len > n)

	{

	  while (left-- > 0 && n < (ssize_t) len)

	    buf[n++] = '0';

	  buf[n] = '\0';

	}

    }

  return 0;

}

int

__APPEND (FUNC_PREFIX, ecvt_r) (FLOAT_TYPE value, int ndigit, int *decpt,

				int *sign, char *buf, size_t len)

{

  int exponent = 0;

  if (isfinite (value) && value != 0.0)

    {

      /* Slow code that doesn't require -lm functions.  */

      FLOAT_TYPE d;

      FLOAT_TYPE f = 1.0;

      if (value < 0.0)

	d = -value;

      else

	d = value;

      /* For denormalized numbers the d < 1.0 case below won't work,

	 as f can overflow to +Inf.  */

      if (d < FLOAT_MIN_10_NORM)

	{

	  value /= FLOAT_MIN_10_NORM;

	  if (value < 0.0)

	    d = -value;

	  else

	    d = value;

	  exponent += FLOAT_MIN_10_EXP;

	}

      if (d < 1.0)

	{

	  do

	    {

	      f *= 10.0;

	      --exponent;

	    }

	  while (d * f < 1.0);

	  value *= f;

	}

      else if (d >= 10.0)

	{

	  do

	    {

	      f *= 10;

	      ++exponent;

	    }

	  while (d >= f * 10.0);

	  value /= f;

	}

    }

  else if (value == 0.0)

    /* SUSv2 leaves it unspecified whether *DECPT is 0 or 1 for 0.0.

       This could be changed to -1 if we want to return 0.  */

    exponent = 0;

  if (ndigit <= 0 && len > 0)

    {

      buf[0] = '\0';

      *decpt = 1;

      *sign = isfinite (value) ? signbit (value) != 0 : 0;

    }

  else

    if (__APPEND (FUNC_PREFIX, fcvt_r) (value, MIN (ndigit, NDIGIT_MAX) - 1,

					decpt, sign, buf, len))

      return -1;

  *decpt += exponent;

  return 0;

}

#if LONG_DOUBLE_COMPAT (libc, GLIBC_2_0)

# ifdef LONG_DOUBLE_CVT

#  define cvt_symbol(symbol) \

  cvt_symbol_1 (libc, __APPEND (FUNC_PREFIX, symbol), \

	      APPEND (FUNC_PREFIX, symbol), GLIBC_2_4)

#  define cvt_symbol_1(lib, local, symbol, version) \

    libc_hidden_def (local) \

    versioned_symbol (lib, local, symbol, version)

# else

#  define cvt_symbol(symbol) \

  cvt_symbol_1 (libc, __APPEND (FUNC_PREFIX, symbol), \

	      APPEND (q, symbol), GLIBC_2_0); \

  weak_alias (__APPEND (FUNC_PREFIX, symbol), APPEND (FUNC_PREFIX, symbol))

#  define cvt_symbol_1(lib, local, symbol, version) \

  libc_hidden_def (local) \

  compat_symbol (lib, local, symbol, version)

# endif

#else

# define cvt_symbol(symbol) \

  cvt_symbol_1 (__APPEND (FUNC_PREFIX, symbol), APPEND (FUNC_PREFIX, symbol))

#  define cvt_symbol_1(local, symbol) \

  libc_hidden_def (local) \

  weak_alias (local, symbol)

#endif

cvt_symbol(fcvt_r);

cvt_symbol(ecvt_r);