1/* expr.h -> header file for expr.c
2   Copyright 1987, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
3   2002, 2003 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, 51 Franklin Street - Fifth Floor, Boston, MA
20   02110-1301, USA.  */
21
22/*
23 * By popular demand, we define a struct to represent an expression.
24 * This will no doubt mutate as expressions become baroque.
25 *
26 * Currently, we support expressions like "foo OP bar + 42".  In other
27 * words we permit a (possibly undefined) symbol, a (possibly
28 * undefined) symbol and the operation used to combine the symbols,
29 * and an (absolute) augend.  RMS says this is so we can have 1-pass
30 * assembly for any compiler emissions, and a 'case' statement might
31 * emit 'undefined1 - undefined2'.
32 *
33 * The type of an expression used to be stored as a segment.  That got
34 * confusing because it overloaded the concept of a segment.  I added
35 * an operator field, instead.
36 */
37
38/* This is the type of an expression.  The operator types are also
39   used while parsing an expression.
40
41   NOTE: This enumeration must match the op_rank array in expr.c.  */
42
43typedef enum {
44  /* An illegal expression.  */
45  O_illegal,
46  /* A nonexistent expression.  */
47  O_absent,
48  /* X_add_number (a constant expression).  */
49  O_constant,
50  /* X_add_symbol + X_add_number.  */
51  O_symbol,
52  /* X_add_symbol + X_add_number - the base address of the image.  */
53  O_symbol_rva,
54  /* A register (X_add_number is register number).  */
55  O_register,
56  /* A big value.  If X_add_number is negative or 0, the value is in
57     generic_floating_point_number.  Otherwise the value is in
58     generic_bignum, and X_add_number is the number of LITTLENUMs in
59     the value.  */
60  O_big,
61  /* (- X_add_symbol) + X_add_number.  */
62  O_uminus,
63  /* (~ X_add_symbol) + X_add_number.  */
64  O_bit_not,
65  /* (! X_add_symbol) + X_add_number.  */
66  O_logical_not,
67  /* (X_add_symbol * X_op_symbol) + X_add_number.  */
68  O_multiply,
69  /* (X_add_symbol / X_op_symbol) + X_add_number.  */
70  O_divide,
71  /* (X_add_symbol % X_op_symbol) + X_add_number.  */
72  O_modulus,
73  /* (X_add_symbol << X_op_symbol) + X_add_number.  */
74  O_left_shift,
75  /* (X_add_symbol >> X_op_symbol) + X_add_number.  */
76  O_right_shift,
77  /* (X_add_symbol | X_op_symbol) + X_add_number.  */
78  O_bit_inclusive_or,
79  /* (X_add_symbol |~ X_op_symbol) + X_add_number.  */
80  O_bit_or_not,
81  /* (X_add_symbol ^ X_op_symbol) + X_add_number.  */
82  O_bit_exclusive_or,
83  /* (X_add_symbol & X_op_symbol) + X_add_number.  */
84  O_bit_and,
85  /* (X_add_symbol + X_op_symbol) + X_add_number.  */
86  O_add,
87  /* (X_add_symbol - X_op_symbol) + X_add_number.  */
88  O_subtract,
89  /* (X_add_symbol == X_op_symbol) + X_add_number.  */
90  O_eq,
91  /* (X_add_symbol != X_op_symbol) + X_add_number.  */
92  O_ne,
93  /* (X_add_symbol < X_op_symbol) + X_add_number.  */
94  O_lt,
95  /* (X_add_symbol <= X_op_symbol) + X_add_number.  */
96  O_le,
97  /* (X_add_symbol >= X_op_symbol) + X_add_number.  */
98  O_ge,
99  /* (X_add_symbol > X_op_symbol) + X_add_number.  */
100  O_gt,
101  /* (X_add_symbol && X_op_symbol) + X_add_number.  */
102  O_logical_and,
103  /* (X_add_symbol || X_op_symbol) + X_add_number.  */
104  O_logical_or,
105  /* X_op_symbol [ X_add_symbol ] */
106  O_index,
107  /* machine dependent operators */
108  O_md1,  O_md2,  O_md3,  O_md4,  O_md5,  O_md6,  O_md7,  O_md8,
109  O_md9,  O_md10, O_md11, O_md12, O_md13, O_md14, O_md15, O_md16,
110  O_md17, O_md18, O_md19, O_md20, O_md21, O_md22, O_md23, O_md24,
111  O_md25, O_md26, O_md27, O_md28, O_md29, O_md30, O_md31, O_md32,
112  /* this must be the largest value */
113  O_max
114} operatorT;
115
116typedef struct expressionS {
117  /* The main symbol.  */
118  symbolS *X_add_symbol;
119  /* The second symbol, if needed.  */
120  symbolS *X_op_symbol;
121  /* A number to add.  */
122  offsetT X_add_number;
123
124  /* The type of the expression.  We can't assume that an arbitrary
125     compiler can handle a bitfield of enum type.  FIXME: We could
126     check this using autoconf.  */
127#ifdef __GNUC__
128  operatorT X_op : 8;
129#else
130  unsigned char X_op;
131#endif
132
133  /* Non-zero if X_add_number should be regarded as unsigned.  This is
134     only valid for O_constant expressions.  It is only used when an
135     O_constant must be extended into a bignum (i.e., it is not used
136     when performing arithmetic on these values).
137     FIXME: This field is not set very reliably.  */
138  unsigned int X_unsigned : 1;
139
140  /* 7 additional bits can be defined if needed.  */
141
142  /* Machine dependent field */
143  unsigned short X_md;
144} expressionS;
145
146enum expr_mode
147{
148  expr_evaluate,
149  expr_normal,
150  expr_defer
151};
152
153/* "result" should be type (expressionS *).  */
154#define expression(result) expr (0, result, expr_normal)
155#define expression_and_evaluate(result) expr (0, result, expr_evaluate)
156#define deferred_expression(result) expr (0, result, expr_defer)
157
158/* If an expression is O_big, look here for its value. These common
159   data may be clobbered whenever expr() is called.  */
160/* Flonums returned here.  Big enough to hold most precise flonum.  */
161extern FLONUM_TYPE generic_floating_point_number;
162/* Bignums returned here.  */
163extern LITTLENUM_TYPE generic_bignum[];
164/* Number of littlenums in above.  */
165#define SIZE_OF_LARGE_NUMBER (20)
166
167typedef char operator_rankT;
168
169extern char get_symbol_end (void);
170extern void expr_begin (void);
171extern void expr_set_precedence (void);
172extern segT expr (int, expressionS *, enum expr_mode);
173extern unsigned int get_single_number (void);
174extern symbolS *make_expr_symbol (expressionS * expressionP);
175extern int expr_symbol_where (symbolS *, char **, unsigned int *);
176
177extern symbolS *expr_build_uconstant (offsetT);
178extern symbolS *expr_build_dot (void);
179
180int resolve_expression (expressionS *);
181