expr.h revision 33965 
1/* expr.h -> header file for expr.c
2   Copyright (C) 1987, 92, 93, 94, 95, 96, 1997 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 2, 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, 59 Temple Place - Suite 330, Boston, MA
19   02111-1307, USA.  */
20
21/*
22 * By popular demand, we define a struct to represent an expression.
23 * This will no doubt mutate as expressions become baroque.
24 *
25 * Currently, we support expressions like "foo OP bar + 42".  In other
26 * words we permit a (possibly undefined) symbol, a (possibly
27 * undefined) symbol and the operation used to combine the symbols,
28 * and an (absolute) augend.  RMS says this is so we can have 1-pass
29 * assembly for any compiler emissions, and a 'case' statement might
30 * emit 'undefined1 - undefined2'.
31 *
32 * The type of an expression used to be stored as a segment.  That got
33 * confusing because it overloaded the concept of a segment.  I added
34 * an operator field, instead.
35 */
36
37/* This is the type of an expression.  The operator types are also
38   used while parsing an expression.
39
40   NOTE: This enumeration must match the op_rank array in expr.c.  */
41
42typedef enum
43{
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  /* this must be the largest value */
106  O_max
107} operatorT;
108
109typedef struct expressionS
110{
111  /* The main symbol.  */
112  struct symbol *X_add_symbol;
113  /* The second symbol, if needed.  */
114  struct symbol *X_op_symbol;
115  /* A number to add.  */
116  offsetT X_add_number;
117  /* The type of the expression.  We can't assume that an arbitrary
118     compiler can handle a bitfield of enum type.  FIXME: We could
119     check this using autoconf.  */
120#ifdef __GNUC__
121  operatorT X_op : 5;
122#else
123  unsigned X_op : 5;
124#endif
125  /* Non-zero if X_add_number should be regarded as unsigned.  This is
126     only valid for O_constant expressions.  It is only used when an
127     O_constant must be extended into a bignum (i.e., it is not used
128     when performing arithmetic on these values).
129     FIXME: This field is not set very reliably.  */
130  unsigned int X_unsigned : 1;
131} expressionS;
132
133/* "result" should be type (expressionS *). */
134#define expression(result) expr (0, result)
135
136/* If an expression is O_big, look here for its value. These common
137   data may be clobbered whenever expr() is called. */
138/* Flonums returned here.  Big enough to hold most precise flonum. */
139extern FLONUM_TYPE generic_floating_point_number;
140/* Bignums returned here. */
141extern LITTLENUM_TYPE generic_bignum[];
142/* Number of littlenums in above. */
143#define SIZE_OF_LARGE_NUMBER (20)
144
145typedef char operator_rankT;
146
147extern char get_symbol_end PARAMS ((void));
148extern void expr_begin PARAMS ((void));
149extern segT expr PARAMS ((int rank, expressionS * resultP));
150extern unsigned int get_single_number PARAMS ((void));
151extern struct symbol *make_expr_symbol PARAMS ((expressionS * expressionP));
152extern int expr_symbol_where
153  PARAMS ((struct symbol *, char **, unsigned int *));
154
155/* end of expr.h */
156