source: trunk/third/binutils/gas/flonum.h @ 16965

Revision 16965, 4.0 KB checked in by ghudson, 22 years ago (diff)
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1/* flonum.h - Floating point package
2   Copyright 1987, 1990, 1991, 1992, 1994, 1996, 2000
3   Free Software Foundation, Inc.
4
5   This file is part of GAS, the GNU Assembler.
6
7   GAS is free software; you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by
9   the Free Software Foundation; either version 2, or (at your option)
10   any later version.
11
12   GAS is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with GAS; see the file COPYING.  If not, write to the Free
19   Software Foundation, 59 Temple Place - Suite 330, Boston, MA
20   02111-1307, USA.  */
21
22/***********************************************************************\
23 *                                                                      *
24 *      Arbitrary-precision floating point arithmetic.                  *
25 *                                                                      *
26 *                                                                      *
27 *      Notation: a floating point number is expressed as               *
28 *      MANTISSA * (2 ** EXPONENT).                                     *
29 *                                                                      *
30 *      If this offends more traditional mathematicians, then           *
31 *      please tell me your nomenclature for flonums!                   *
32 *                                                                      *
33 \***********************************************************************/
34
35#include "bignum.h"
36
37/***********************************************************************\
38 *                                                                      *
39 *      Variable precision floating point numbers.                      *
40 *                                                                      *
41 *      Exponent is the place value of the low littlenum. E.g.:         *
42 *      If  0:  low points to the units             littlenum.          *
43 *      If  1:  low points to the LITTLENUM_RADIX   littlenum.          *
44 *      If -1:  low points to the 1/LITTLENUM_RADIX littlenum.          *
45 *                                                                      *
46 \***********************************************************************/
47
48/* JF:  A sign value of 0 means we have been asked to assemble NaN
49   A sign value of 'P' means we've been asked to assemble +Inf
50   A sign value of 'N' means we've been asked to assemble -Inf
51   */
52struct FLONUM_STRUCT {
53  LITTLENUM_TYPE *low;          /* low order littlenum of a bignum */
54  LITTLENUM_TYPE *high;         /* high order littlenum of a bignum */
55  LITTLENUM_TYPE *leader;       /* -> 1st non-zero littlenum */
56  /* If flonum is 0.0, leader==low-1 */
57  long exponent;                /* base LITTLENUM_RADIX */
58  char sign;                    /* '+' or '-' */
59};
60
61typedef struct FLONUM_STRUCT FLONUM_TYPE;
62
63/***********************************************************************\
64 *                                                                      *
65 *      Since we can (& do) meet with exponents like 10^5000, it        *
66 *      is silly to make a table of ~ 10,000 entries, one for each      *
67 *      power of 10. We keep a table where item [n] is a struct         *
68 *      FLONUM_FLOATING_POINT representing 10^(2^n). We then            *
69 *      multiply appropriate entries from this table to get any         *
70 *      particular power of 10. For the example of 10^5000, a table     *
71 *      of just 25 entries suffices: 10^(2^-12)...10^(2^+12).           *
72 *                                                                      *
73 \***********************************************************************/
74
75extern const FLONUM_TYPE flonum_positive_powers_of_ten[];
76extern const FLONUM_TYPE flonum_negative_powers_of_ten[];
77extern const int table_size_of_flonum_powers_of_ten;
78/* Flonum_XXX_powers_of_ten[] table has legal indices from 0 to
79   + this number inclusive.  */
80
81/***********************************************************************\
82 *                                                                      *
83 *      Declare worker functions.                                       *
84 *                                                                      *
85 \***********************************************************************/
86
87int atof_generic PARAMS ((char **address_of_string_pointer,
88                          const char *string_of_decimal_marks,
89                          const char *string_of_decimal_exponent_marks,
90                          FLONUM_TYPE * address_of_generic_floating_point_number));
91
92void flonum_copy PARAMS ((FLONUM_TYPE * in, FLONUM_TYPE * out));
93void flonum_multip PARAMS ((const FLONUM_TYPE * a, const FLONUM_TYPE * b,
94                            FLONUM_TYPE * product));
95
96/***********************************************************************\
97 *                                                                      *
98 *      Declare error codes.                                            *
99 *                                                                      *
100 \***********************************************************************/
101
102#define ERROR_EXPONENT_OVERFLOW (2)
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