1#ifndef _EXPR_H_
2#define _EXPR_H_
3/* expr.h -> header file for expr.c
4   Copyright (C) 1987 Free Software Foundation, Inc.
5
6This file is part of GAS, the GNU Assembler.
7
8GAS is free software; you can redistribute it and/or modify
9it under the terms of the GNU General Public License as published by
10the Free Software Foundation; either version 1, or (at your option)
11any later version.
12
13GAS is distributed in the hope that it will be useful,
14but WITHOUT ANY WARRANTY; without even the implied warranty of
15MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16GNU General Public License for more details.
17
18You should have received a copy of the GNU General Public License
19along with GAS; see the file COPYING.  If not, write to
20the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
21
22#include "as.h"
23#import "struc-symbol.h"
24#import "bignum.h"
25#import "flonum.h"
26
27enum {
28  /* FROM expr.h line 46 */
29  /* A nonexistent expression.  */
30  O_absent = SEG_NONE, /* HACK, this isn't going to work, absent ones come up
31			  illegal currently.  */
32  /* X_add_symbol + X_add_number.  */
33  O_symbol = SEG_SECT,
34  /* X_add_number (a constant expression).  */
35  O_constant = SEG_ABSOLUTE,
36  /* A big value.  If X_add_number is negative or 0, the value is in
37     generic_floating_point_number.  Otherwise the value is in
38     generic_bignum, and X_add_number is the number of LITTLENUMs in
39     the value.  */
40  O_big = SEG_BIG,
41};
42
43extern char *seg_name[];
44extern segT N_TYPE_seg[];
45
46/*
47 * When an expression is SEG_BIG, it is in these globals (see comments above
48 * about SEG_BIG).  This data may be clobbered whenever expr() is called.
49 */
50extern FLONUM_TYPE    generic_floating_point_number;
51extern LITTLENUM_TYPE generic_bignum[];
52#define SIZE_OF_LARGE_NUMBER (20)	/* Number of littlenums in above */
53					/* generic_bignum which is enough to */
54					/* hold most precise flonum. */
55
56/*
57 * Abbreviations (mnemonics).
58 *
59 *	O	operator
60 *	Q	quantity,  operand
61 *	X	eXpression
62 */
63
64/*
65 * By popular demand, we define a struct to represent an expression.
66 * This will no doubt mutate as expressions become baroque.
67 *
68 * Currently, we support expressions like "foo-bar+42".
69 * In other words we permit a (possibly undefined) minuend, a
70 * (possibly undefined) subtrahend and an (absolute) augend.
71 * RMS says this is so we can have 1-pass assembly for any compiler
72 * emmissions, and a 'case' statement might emit 'undefined1 - undefined2'.
73 *
74 * To simplify table-driven dispatch, we also have a "segment" for the
75 * entire expression. That way we don't require complex reasoning about
76 * whether particular components are defined; and we can change component
77 * semantics without re-working all the dispatch tables in the assembler.
78 * In other words the "type" of an expression is its segment.
79 */
80
81// This isn't really up to date with GNU as, but it helps for source
82// compatibility.
83#define X_op X_seg
84#define X_op_symbol X_add_symbol
85
86/*
87 * To allow 32-bit architectures to use things like .quad we need to make
88 * all expressions be 64-bit regardless of the target architecture's address
89 * size.
90 */
91#include <stdint.h>
92typedef int64_t signed_expr_t;
93
94typedef struct {
95    symbolS *X_add_symbol;	/* foo */
96    symbolS *X_subtract_symbol;	/* bar */
97    signed_expr_t
98    X_add_number;	/* 42 (must be signed) */
99    segT     X_seg;		/* What segment (expr type) */
100
101	/* Non-zero if X_add_number should be regarded as unsigned.  This is
102     only valid for O_constant expressions.  It is only used when an
103     O_constant must be extended into a bignum (i.e., it is not used
104     when performing arithmetic on these values).
105     FIXME: This field is not set very reliably.  */
106	unsigned int X_unsigned : 1,
107
108	/* Non-zero if we have the special assembly time constant expression
109     of the difference of two symbols defined in the same section then divided
110     by exactly 2. */
111		     X_sectdiff_divide_by_two : 1;
112} expressionS;
113
114extern segT expression(
115    expressionS *resultP);
116extern char get_symbol_end(
117    void);
118extern segT try_to_make_absolute(
119    expressionS *expressionP);
120/* FROM line 165 */
121extern symbolS *make_expr_symbol (expressionS * expressionP);
122
123extern symbolS *expr_build_uconstant (offsetT);
124#endif /* _EXPR_H_ */
125