binutils-gdb/gas/flonum.h

/* flonum.h - Floating point package
   Copyright 1987, 1990, 1991, 1992, 1994, 1996, 2000, 2003, 2005, 2007
   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.  */

/***********************************************************************\
 *									*
 *	Arbitrary-precision floating point arithmetic.			*
 *									*
 *									*
 *	Notation: a floating point number is expressed as		*
 *	MANTISSA * (2 ** EXPONENT).					*
 *									*
 *	If this offends more traditional mathematicians, then		*
 *	please tell me your nomenclature for flonums!			*
 *									*
 \***********************************************************************/

#include "bignum.h"

/***********************************************************************\
 *									*
 *	Variable precision floating point numbers.			*
 *									*
 *	Exponent is the place value of the low littlenum. E.g.:		*
 *	If  0:  low points to the units             littlenum.		*
 *	If  1:  low points to the LITTLENUM_RADIX   littlenum.		*
 *	If -1:  low points to the 1/LITTLENUM_RADIX littlenum.		*
 *									*
 \***********************************************************************/

/* JF:  A sign value of 0 means we have been asked to assemble NaN
   A sign value of 'P' means we've been asked to assemble +Inf
   A sign value of 'N' means we've been asked to assemble -Inf
   */
struct FLONUM_STRUCT {
  LITTLENUM_TYPE *low;		/* low order littlenum of a bignum */
  LITTLENUM_TYPE *high;		/* high order littlenum of a bignum */
  LITTLENUM_TYPE *leader;	/* -> 1st non-zero littlenum */
  /* If flonum is 0.0, leader==low-1 */
  long exponent;		/* base LITTLENUM_RADIX */
  char sign;			/* '+' or '-' */
};

typedef struct FLONUM_STRUCT FLONUM_TYPE;

/***********************************************************************\
 *									*
 *	Since we can (& do) meet with exponents like 10^5000, it	*
 *	is silly to make a table of ~ 10,000 entries, one for each	*
 *	power of 10. We keep a table where item [n] is a struct		*
 *	FLONUM_FLOATING_POINT representing 10^(2^n). We then		*
 *	multiply appropriate entries from this table to get any		*
 *	particular power of 10. For the example of 10^5000, a table	*
 *	of just 25 entries suffices: 10^(2^-12)...10^(2^+12).		*
 *									*
 \***********************************************************************/

extern const FLONUM_TYPE flonum_positive_powers_of_ten[];
extern const FLONUM_TYPE flonum_negative_powers_of_ten[];
extern const int table_size_of_flonum_powers_of_ten;
/* Flonum_XXX_powers_of_ten[] table has legal indices from 0 to
   + this number inclusive.  */

/***********************************************************************\
 *									*
 *	Declare worker functions.					*
 *									*
 \***********************************************************************/

int atof_generic (char **address_of_string_pointer,
		  const char *string_of_decimal_marks,
		  const char *string_of_decimal_exponent_marks,
		  FLONUM_TYPE * address_of_generic_floating_point_number);

void flonum_copy (FLONUM_TYPE * in, FLONUM_TYPE * out);
void flonum_multip (const FLONUM_TYPE * a, const FLONUM_TYPE * b,
		    FLONUM_TYPE * product);

/***********************************************************************\
 *									*
 *	Declare error codes.						*
 *									*
 \***********************************************************************/

#define ERROR_EXPONENT_OVERFLOW (2)