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/* atof_generic.c - turn a string of digits into a Flonum

   Copyright (C) 1987-2015 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 3, 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, 51 Franklin Street - Fifth Floor, Boston, MA

   02110-1301, USA.  */

#include "as.h"

#include "safe-ctype.h"

#ifndef FALSE

#define FALSE (0)

#endif

#ifndef TRUE

#define TRUE  (1)

#endif

#ifdef TRACE

static void flonum_print (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:

   ::=   

   ::= '+' | '-' | {empty}

   ::= 

  |  

  |   

  |  

   ::= {empty}

  |   

   ::=  |  

   ::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'

   ::= {one character from "string_of_decimal_exponent_marks"}

   ::= {one character from "string_of_decimal_marks"}

  */

int

atof_generic (/* 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

  gas_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 (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 (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 (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 (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;

      unsigned int more_than_enough_bits_for_digits;

      unsigned int more_than_enough_littlenums_for_digits;

      unsigned int size_of_digits_in_littlenums;

      unsigned int size_of_digits_in_chars;

      FLONUM_TYPE power_of_10_flonum;

      FLONUM_TYPE digits_flonum;

      precision = (address_of_generic_floating_point_number->high

		   - address_of_generic_floating_point_number->low

		   + 1);	/* Number of destination littlenums.  */

      /* Includes guard bits (two littlenums worth) */

      maximum_useful_digits = (((precision - 2))

			       * ( (LITTLENUM_NUMBER_OF_BITS))

			       * 1000000 / 3321928)

	+ 2;			/* 2 :: guard digits.  */

      if (number_of_digits_available > maximum_useful_digits)

	{

	  number_of_digits_to_use = maximum_useful_digits;

	}

      else

	{

	  number_of_digits_to_use = number_of_digits_available;

	}

      /* Cast these to SIGNED LONG first, otherwise, on systems with

	 LONG wider than INT (such as Alpha OSF/1), unsignedness may

	 cause unexpected results.  */

      decimal_exponent += ((long) number_of_digits_before_decimal

			   - (long) number_of_digits_to_use);

      more_than_enough_bits_for_digits

	= (number_of_digits_to_use * 3321928 / 1000000 + 1);

      more_than_enough_littlenums_for_digits

	= (more_than_enough_bits_for_digits

	   / LITTLENUM_NUMBER_OF_BITS)

	+ 2;

      /* Compute (digits) part. In "12.34E56" this is the "1234" part.

	 Arithmetic is exact here. If no digits are supplied then this

	 part is a 0 valued binary integer.  Allocate room to build up

	 the binary number as littlenums.  We want this memory to

	 disappear when we leave this function.  Assume no alignment

	 problems => (room for n objects) == n * (room for 1

	 object).  */

      size_of_digits_in_littlenums = more_than_enough_littlenums_for_digits;

      size_of_digits_in_chars = size_of_digits_in_littlenums

	* sizeof (LITTLENUM_TYPE);

      digits_binary_low = (LITTLENUM_TYPE *)

	alloca (size_of_digits_in_chars);

      memset ((char *) digits_binary_low, '\0', size_of_digits_in_chars);

      /* Digits_binary_low[] is allocated and zeroed.  */

      /*

       * Parse the decimal digits as if * digits_low was in the units position.

       * Emit a binary number into digits_binary_low[].

       *

       * Use a large-precision version of:

       * (((1st-digit) * 10 + 2nd-digit) * 10 + 3rd-digit ...) * 10 + last-digit

       */

      for (p = first_digit, count = number_of_digits_to_use; count; p++, --count)

	{

	  c = *p;

	  if (ISDIGIT (c))

	    {

	      /*

	       * Multiply by 10. Assume can never overflow.

	       * Add this digit to digits_binary_low[].

	       */

	      long carry;

	      LITTLENUM_TYPE *littlenum_pointer;

	      LITTLENUM_TYPE *littlenum_limit;

	      littlenum_limit = digits_binary_low

		+ more_than_enough_littlenums_for_digits

		- 1;

	      carry = c - '0';	/* char -> binary */

	      for (littlenum_pointer = digits_binary_low;

		   littlenum_pointer <= littlenum_limit;

		   littlenum_pointer++)

		{

		  long work;

		  work = carry + 10 * (long) (*littlenum_pointer);

		  *littlenum_pointer = work & LITTLENUM_MASK;

		  carry = work >> LITTLENUM_NUMBER_OF_BITS;

		}

	      if (carry != 0)

		{

		  /*

		   * We have a GROSS internal error.

		   * This should never happen.

		   */

		  as_fatal (_("failed sanity check"));

		}

	    }

	  else

	    {

	      ++count;		/* '.' doesn't alter digits used count.  */

	    }

	}

      /*

       * Digits_binary_low[] properly encodes the value of the digits.

       * Forget about any high-order littlenums that are 0.

       */

      while (digits_binary_low[size_of_digits_in_littlenums - 1] == 0

	     && size_of_digits_in_littlenums >= 2)

	size_of_digits_in_littlenums--;

      digits_flonum.low = digits_binary_low;

      digits_flonum.high = digits_binary_low + size_of_digits_in_littlenums - 1;

      digits_flonum.leader = digits_flonum.high;

      digits_flonum.exponent = 0;

      /*

       * The value of digits_flonum . sign should not be important.

       * We have already decided the output's sign.

       * We trust that the sign won't influence the other parts of the number!

       * So we give it a value for these reasons:

       * (1) courtesy to humans reading/debugging

       *     these numbers so they don't get excited about strange values

       * (2) in future there may be more meaning attached to sign,

       *     and what was

       *     harmless noise may become disruptive, ill-conditioned (or worse)

       *     input.

       */

      digits_flonum.sign = '+';

      {

	/*

	 * Compute the mantssa (& exponent) of the power of 10.

	 * If successful, then multiply the power of 10 by the digits

	 * giving return_binary_mantissa and return_binary_exponent.

	 */

	LITTLENUM_TYPE *power_binary_low;

	int decimal_exponent_is_negative;

	/* This refers to the "-56" in "12.34E-56".  */

	/* FALSE: decimal_exponent is positive (or 0) */

	/* TRUE:  decimal_exponent is negative */

	FLONUM_TYPE temporary_flonum;

	LITTLENUM_TYPE *temporary_binary_low;

	unsigned int size_of_power_in_littlenums;

	unsigned int size_of_power_in_chars;

	size_of_power_in_littlenums = precision;

	/* Precision has a built-in fudge factor so we get a few guard bits.  */

	decimal_exponent_is_negative = decimal_exponent < 0;

	if (decimal_exponent_is_negative)

	  {

	    decimal_exponent = -decimal_exponent;

	  }

	/* From now on: the decimal exponent is > 0. Its sign is separate.  */

	size_of_power_in_chars = size_of_power_in_littlenums

	  * sizeof (LITTLENUM_TYPE) + 2;

	power_binary_low = (LITTLENUM_TYPE *) alloca (size_of_power_in_chars);

	temporary_binary_low = (LITTLENUM_TYPE *) alloca (size_of_power_in_chars);

	memset ((char *) power_binary_low, '\0', size_of_power_in_chars);

	*power_binary_low = 1;

	power_of_10_flonum.exponent = 0;

	power_of_10_flonum.low = power_binary_low;

	power_of_10_flonum.leader = power_binary_low;

	power_of_10_flonum.high = power_binary_low + size_of_power_in_littlenums - 1;

	power_of_10_flonum.sign = '+';

	temporary_flonum.low = temporary_binary_low;

	temporary_flonum.high = temporary_binary_low + size_of_power_in_littlenums - 1;

	/*

	 * (power) == 1.

	 * Space for temporary_flonum allocated.

	 */

	/*

	 * ...

	 *

	 * WHILE	more bits

	 * DO	find next bit (with place value)

	 *	multiply into power mantissa

	 * OD

	 */

	{

	  int place_number_limit;

	  /* Any 10^(2^n) whose "n" exceeds this */

	  /* value will fall off the end of */

	  /* flonum_XXXX_powers_of_ten[].  */

	  int place_number;

	  const FLONUM_TYPE *multiplicand;	/* -> 10^(2^n) */

	  place_number_limit = table_size_of_flonum_powers_of_ten;

	  multiplicand = (decimal_exponent_is_negative

			  ? flonum_negative_powers_of_ten

			  : flonum_positive_powers_of_ten);

	  for (place_number = 1;/* Place value of this bit of exponent.  */

	       decimal_exponent;/* Quit when no more 1 bits in exponent.  */

	       decimal_exponent >>= 1, place_number++)

	    {

	      if (decimal_exponent & 1)

		{

		  if (place_number > place_number_limit)

		    {

		      /* The decimal exponent has a magnitude so great

			 that our tables can't help us fragment it.

			 Although this routine is in error because it

			 can't imagine a number that big, signal an

			 error as if it is the user's fault for

			 presenting such a big number.  */

		      return_value = ERROR_EXPONENT_OVERFLOW;

		      /* quit out of loop gracefully */

		      decimal_exponent = 0;

		    }

		  else

		    {

#ifdef TRACE

		      printf ("before multiply, place_number = %d., power_of_10_flonum:\n",

			      place_number);

		      flonum_print (&power_of_10_flonum);

		      (void) putchar ('\n');

#endif

#ifdef TRACE

		      printf ("multiplier:\n");

		      flonum_print (multiplicand + place_number);

		      (void) putchar ('\n');

#endif

		      flonum_multip (multiplicand + place_number,

				     &power_of_10_flonum, &temporary_flonum);

#ifdef TRACE

		      printf ("after multiply:\n");

		      flonum_print (&temporary_flonum);

		      (void) putchar ('\n');

#endif

		      flonum_copy (&temporary_flonum, &power_of_10_flonum);

#ifdef TRACE

		      printf ("after copy:\n");

		      flonum_print (&power_of_10_flonum);

		      (void) putchar ('\n');

#endif

		    } /* If this bit of decimal_exponent was computable.*/

		} /* If this bit of decimal_exponent was set.  */

	    } /* For each bit of binary representation of exponent */

#ifdef TRACE

	  printf ("after computing power_of_10_flonum:\n");

	  flonum_print (&power_of_10_flonum);

	  (void) putchar ('\n');

#endif

	}

      }

      /*

       * power_of_10_flonum is power of ten in binary (mantissa) , (exponent).

       * It may be the number 1, in which case we don't NEED to multiply.

       *

       * Multiply (decimal digits) by power_of_10_flonum.

       */

      flonum_multip (&power_of_10_flonum, &digits_flonum, address_of_generic_floating_point_number);

      /* Assert sign of the number we made is '+'.  */

      address_of_generic_floating_point_number->sign = digits_sign_char;

    }

  return return_value;

}

#ifdef TRACE

static void

flonum_print (f)

     const FLONUM_TYPE *f;

{

  LITTLENUM_TYPE *lp;

  char littlenum_format[10];

  sprintf (littlenum_format, " %%0%dx", sizeof (LITTLENUM_TYPE) * 2);

#define print_littlenum(LP)	(printf (littlenum_format, LP))

  printf ("flonum @%p %c e%ld", f, f->sign, f->exponent);

  if (f->low < f->high)

    for (lp = f->high; lp >= f->low; lp--)

      print_littlenum (*lp);

  else

    for (lp = f->low; lp <= f->high; lp++)

      print_littlenum (*lp);

  printf ("\n");

  fflush (stdout);

}

#endif

/* end of atof_generic.c */