flonum.h   [plain text]

#ifndef _FLONUM_H_
#define _FLONUM_H_
/* flonum.h - Floating point package
   Copyright (C) 1987 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 1, 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, 675 Mass Ave, Cambridge, MA 02139, 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!			*
*									*
\***********************************************************************/

#import "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 int		exponent; /* base LITTLENUM_RADIX */
  char			sign;	/* '+' or '-' */
};

typedef struct FLONUM_STRUCT FLONUM_TYPE;

struct const_FLONUM_STRUCT {
  const LITTLENUM_TYPE *	low;	/* low order littlenum of a bignum */
  const LITTLENUM_TYPE *	high;	/* high order littlenum of a bignum */
  const LITTLENUM_TYPE *	leader;	/* -> 1st non-zero littlenum */
					/* If flonum is 0.0, leader==low-1 */
  long int		exponent; /* base LITTLENUM_RADIX */
  char			sign;	/* '+' or '-' */
};

typedef struct const_FLONUM_STRUCT const_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 const_FLONUM_TYPE flonum_positive_powers_of_ten[];
extern const 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.					*
*									*
\***********************************************************************/

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


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

#define ERROR_EXPONENT_OVERFLOW (2)
#endif /* _FLONUM_H_ */