atof-generic.c

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/* atof_generic.c - turn a string of digits into a Flonum
   Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2000
   Free Software Foundation, Inc.

   This file is part of GAS, the GNU Assembler.

   GAS 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.

   GAS 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 GAS; see the file COPYING.  If not, write to the Free
   Software Foundation, 59 Temple Place - Suite 330, Boston, MA
   02111-1307, USA.  */

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

#include "as.h"

#ifndef FALSE
#define FALSE (0)
#endif
#ifndef TRUE
#define TRUE  (1)
#endif

#ifdef TRACE
static void flonum_print PARAMS ((const FLONUM_TYPE *));
#endif

#define ASSUME_DECIMAL_MARK_IS_DOT

/***********************************************************************\
 *									*
 *	Given a string of decimal digits , with optional decimal	*
 *	mark and optional decimal exponent (place value) of the		*
 *	lowest_order decimal digit: produce a floating point		*
 *	number. The number is 'generic' floating point: our		*
 *	caller will encode it for a specific machine architecture.	*
 *									*
 *	Assumptions							*
 *		uses base (radix) 2					*
 *		this machine uses 2's complement binary integers	*
 *		target flonums use "      "         "       "		*
 *		target flonums exponents fit in a long			*
 *									*
 \***********************************************************************/

/*

  Syntax:

  <flonum> ::= <optional-sign> <decimal-number> <optional-exponent>
  <optional-sign> ::= '+' | '-' | {empty}
  <decimal-number> ::= <integer>
  | <integer> <radix-character>
  | <integer> <radix-character> <integer>
  | <radix-character> <integer>

  <optional-exponent> ::= {empty}
  | <exponent-character> <optional-sign> <integer>

  <integer> ::= <digit> | <digit> <integer>
  <digit> ::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'
  <exponent-character> ::= {one character from "string_of_decimal_exponent_marks"}
  <radix-character> ::= {one character from "string_of_decimal_marks"}

  */

int
atof_generic (address_of_string_pointer,
	      string_of_decimal_marks,
	      string_of_decimal_exponent_marks,
	      address_of_generic_floating_point_number)
     /* return pointer to just AFTER number we read.  */
     char **address_of_string_pointer;
     /* At most one per number.  */
     const char *string_of_decimal_marks;
     const char *string_of_decimal_exponent_marks;
     FLONUM_TYPE *address_of_generic_floating_point_number;
{
  int return_value;		/* 0 means OK.  */
  char *first_digit;
  unsigned int number_of_digits_before_decimal;
  unsigned int number_of_digits_after_decimal;
  long decimal_exponent;
  unsigned int number_of_digits_available;
  char digits_sign_char;

  /*
   * Scan the input string, abstracting (1)digits (2)decimal mark (3) exponent.
   * It would be simpler to modify the string, but we don't; just to be nice
   * to caller.
   * We need to know how many digits we have, so we can allocate space for
   * the digits' value.
   */

  char *p;
  char c;
  int seen_significant_digit;

#ifdef ASSUME_DECIMAL_MARK_IS_DOT
  assert (string_of_decimal_marks[0] == '.'
	  && string_of_decimal_marks[1] == 0);
#define IS_DECIMAL_MARK(c)	((c) == '.')
#else
#define IS_DECIMAL_MARK(c)	(0 != strchr (string_of_decimal_marks, (c)))
#endif

  first_digit = *address_of_string_pointer;
  c = *first_digit;

  if (c == '-' || c == '+')
    {
      digits_sign_char = c;
      first_digit++;
    }
  else
    digits_sign_char = '+';

  switch (first_digit[0])
    {
    case 'n':
    case 'N':
      if (!strncasecmp ("nan", first_digit, 3))
	{
	  address_of_generic_floating_point_number->sign = 0;
	  address_of_generic_floating_point_number->exponent = 0;
	  address_of_generic_floating_point_number->leader =
	    address_of_generic_floating_point_number->low;
	  *address_of_string_pointer = first_digit + 3;
	  return 0;
	}
      break;

    case 'i':
    case 'I':
      if (!strncasecmp ("inf", first_digit, 3))
	{
	  address_of_generic_floating_point_number->sign =
	    digits_sign_char == '+' ? 'P' : 'N';
	  address_of_generic_floating_point_number->exponent = 0;
	  address_of_generic_floating_point_number->leader =
	    address_of_generic_floating_point_number->low;

	  first_digit += 3;
	  if (!strncasecmp ("inity", first_digit, 5))
	    first_digit += 5;

	  *address_of_string_pointer = first_digit;

	  return 0;
	}
      break;
    }

  number_of_digits_before_decimal = 0;
  number_of_digits_after_decimal = 0;
  decimal_exponent = 0;
  seen_significant_digit = 0;
  for (p = first_digit;
       (((c = *p) != '\0')
	&& (!c || !IS_DECIMAL_MARK (c))
	&& (!c || !strchr (string_of_decimal_exponent_marks, c)));
       p++)
    {
      if (isdigit ((unsigned char) c))
	{
	  if (seen_significant_digit || c > '0')
	    {
	      ++number_of_digits_before_decimal;
	      seen_significant_digit = 1;
	    }
	  else
	    {
	      first_digit++;
	    }
	}
      else
	{
	  break;		/* p -> char after pre-decimal digits.  */
	}
    }				/* For each digit before decimal mark.  */

#ifndef OLD_FLOAT_READS
  /* Ignore trailing 0's after the decimal point.  The original code here
   * (ifdef'd out) does not do this, and numbers like
   *	4.29496729600000000000e+09	(2**31)
   * come out inexact for some reason related to length of the digit
   * string.
   */
  if (c && IS_DECIMAL_MARK (c))
    {
      unsigned int zeros = 0;	/* Length of current string of zeros */

      for (p++; (c = *p) && isdigit ((unsigned char) c); p++)
	{
	  if (c == '0')
	    {
	      zeros++;
	    }
	  else
	    {
	      number_of_digits_after_decimal += 1 + zeros;
	      zeros = 0;
	    }
	}
    }
#else
  if (c && IS_DECIMAL_MARK (c))
    {
      for (p++;
	   (((c = *p) != '\0')
	    && (!c || !strchr (string_of_decimal_exponent_marks, c)));
	   p++)
	{
	  if (isdigit ((unsigned char) c))
	    {
	      /* This may be retracted below.  */
	      number_of_digits_after_decimal++;

	      if ( /* seen_significant_digit || */ c > '0')
		{
		  seen_significant_digit = TRUE;
		}
	    }
	  else
	    {
	      if (!seen_significant_digit)
		{
		  number_of_digits_after_decimal = 0;
		}
	      break;
	    }
	}			/* For each digit after decimal mark.  */
    }

  while (number_of_digits_after_decimal
	 && first_digit[number_of_digits_before_decimal
			+ number_of_digits_after_decimal] == '0')
    --number_of_digits_after_decimal;
#endif

  if (flag_m68k_mri)
    {
      while (c == '_')
	c = *++p;
    }
  if (c && strchr (string_of_decimal_exponent_marks, c))
    {
      char digits_exponent_sign_char;

      c = *++p;
      if (flag_m68k_mri)
	{
	  while (c == '_')
	    c = *++p;
	}
      if (c && strchr ("+-", c))
	{
	  digits_exponent_sign_char = c;
	  c = *++p;
	}
      else
	{
	  digits_exponent_sign_char = '+';
	}

      for (; (c); c = *++p)
	{
	  if (isdigit ((unsigned char) c))
	    {
	      decimal_exponent = decimal_exponent * 10 + c - '0';
	      /*
	       * BUG! If we overflow here, we lose!
	       */
	    }
	  else
	    {
	      break;
	    }
	}

      if (digits_exponent_sign_char == '-')
	{
	  decimal_exponent = -decimal_exponent;
	}
    }

  *address_of_string_pointer = p;

  number_of_digits_available =
    number_of_digits_before_decimal + number_of_digits_after_decimal;
  return_value = 0;
  if (number_of_digits_available == 0)
    {
      address_of_generic_floating_point_number->exponent = 0;	/* Not strictly necessary */
      address_of_generic_floating_point_number->leader
	= -1 + address_of_generic_floating_point_number->low;
      address_of_generic_floating_point_number->sign = digits_sign_char;
      /* We have just concocted (+/-)0.0E0 */

    }
  else
    {
      int count;		/* Number of useful digits left to scan.  */

      LITTLENUM_TYPE *digits_binary_low;
      unsigned int precision;
      unsigned int maximum_useful_digits;
      unsigned int number_of_digits_to_use;