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      1 /* flonum.h - Floating point package
      2    Copyright (C) 1987-2016 Free Software Foundation, Inc.
      3 
      4    This file is part of GAS, the GNU Assembler.
      5 
      6    GAS is free software; you can redistribute it and/or modify
      7    it under the terms of the GNU General Public License as published by
      8    the Free Software Foundation; either version 3, or (at your option)
      9    any later version.
     10 
     11    GAS is distributed in the hope that it will be useful,
     12    but WITHOUT ANY WARRANTY; without even the implied warranty of
     13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     14    GNU General Public License for more details.
     15 
     16    You should have received a copy of the GNU General Public License
     17    along with GAS; see the file COPYING.  If not, write to the Free
     18    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
     19    02110-1301, USA.  */
     20 
     21 /***********************************************************************\
     22  *									*
     23  *	Arbitrary-precision floating point arithmetic.			*
     24  *									*
     25  *									*
     26  *	Notation: a floating point number is expressed as		*
     27  *	MANTISSA * (2 ** EXPONENT).					*
     28  *									*
     29  *	If this offends more traditional mathematicians, then		*
     30  *	please tell me your nomenclature for flonums!			*
     31  *									*
     32  \***********************************************************************/
     33 
     34 #include "bignum.h"
     35 
     36 /***********************************************************************\
     37  *									*
     38  *	Variable precision floating point numbers.			*
     39  *									*
     40  *	Exponent is the place value of the low littlenum. E.g.:		*
     41  *	If  0:  low points to the units             littlenum.		*
     42  *	If  1:  low points to the LITTLENUM_RADIX   littlenum.		*
     43  *	If -1:  low points to the 1/LITTLENUM_RADIX littlenum.		*
     44  *									*
     45  \***********************************************************************/
     46 
     47 /* JF:  A sign value of 0 means we have been asked to assemble NaN
     48    A sign value of 'P' means we've been asked to assemble +Inf
     49    A sign value of 'N' means we've been asked to assemble -Inf
     50    */
     51 struct FLONUM_STRUCT {
     52   LITTLENUM_TYPE *low;		/* low order littlenum of a bignum */
     53   LITTLENUM_TYPE *high;		/* high order littlenum of a bignum */
     54   LITTLENUM_TYPE *leader;	/* -> 1st non-zero littlenum */
     55   /* If flonum is 0.0, leader==low-1 */
     56   long exponent;		/* base LITTLENUM_RADIX */
     57   char sign;			/* '+' or '-' */
     58 };
     59 
     60 typedef struct FLONUM_STRUCT FLONUM_TYPE;
     61 
     62 /***********************************************************************\
     63  *									*
     64  *	Since we can (& do) meet with exponents like 10^5000, it	*
     65  *	is silly to make a table of ~ 10,000 entries, one for each	*
     66  *	power of 10. We keep a table where item [n] is a struct		*
     67  *	FLONUM_FLOATING_POINT representing 10^(2^n). We then		*
     68  *	multiply appropriate entries from this table to get any		*
     69  *	particular power of 10. For the example of 10^5000, a table	*
     70  *	of just 25 entries suffices: 10^(2^-12)...10^(2^+12).		*
     71  *									*
     72  \***********************************************************************/
     73 
     74 extern const FLONUM_TYPE flonum_positive_powers_of_ten[];
     75 extern const FLONUM_TYPE flonum_negative_powers_of_ten[];
     76 extern const int table_size_of_flonum_powers_of_ten;
     77 /* Flonum_XXX_powers_of_ten[] table has legal indices from 0 to
     78    + this number inclusive.  */
     79 
     80 /***********************************************************************\
     81  *									*
     82  *	Declare worker functions.					*
     83  *									*
     84  \***********************************************************************/
     85 
     86 int atof_generic (char **address_of_string_pointer,
     87 		  const char *string_of_decimal_marks,
     88 		  const char *string_of_decimal_exponent_marks,
     89 		  FLONUM_TYPE * address_of_generic_floating_point_number);
     90 
     91 void flonum_copy (FLONUM_TYPE * in, FLONUM_TYPE * out);
     92 void flonum_multip (const FLONUM_TYPE * a, const FLONUM_TYPE * b,
     93 		    FLONUM_TYPE * product);
     94 
     95 /***********************************************************************\
     96  *									*
     97  *	Declare error codes.						*
     98  *									*
     99  \***********************************************************************/
    100 
    101 #define ERROR_EXPONENT_OVERFLOW (2)
    102