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