expr.h revision 77298 
1/* expr.h -> header file for expr.c
2   Copyright (C) 1987, 92-99, 2000 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  /* An illegal expression.  */
44  O_illegal,
45  /* A nonexistent expression.  */
46  O_absent,
47  /* X_add_number (a constant expression).  */
48  O_constant,
49  /* X_add_symbol + X_add_number.  */
50  O_symbol,
51  /* X_add_symbol + X_add_number - the base address of the image.  */
52  O_symbol_rva,
53  /* A register (X_add_number is register number).  */
54  O_register,
55  /* A big value.  If X_add_number is negative or 0, the value is in
56     generic_floating_point_number.  Otherwise the value is in
57     generic_bignum, and X_add_number is the number of LITTLENUMs in
58     the value.  */
59  O_big,
60  /* (- X_add_symbol) + X_add_number.  */
61  O_uminus,
62  /* (~ X_add_symbol) + X_add_number.  */
63  O_bit_not,
64  /* (! X_add_symbol) + X_add_number.  */
65  O_logical_not,
66  /* (X_add_symbol * X_op_symbol) + X_add_number.  */
67  O_multiply,
68  /* (X_add_symbol / X_op_symbol) + X_add_number.  */
69  O_divide,
70  /* X_add_symbol % X_op_symbol) + X_add_number.  */
71  O_modulus,
72  /* X_add_symbol << X_op_symbol) + X_add_number.  */
73  O_left_shift,
74  /* X_add_symbol >> X_op_symbol) + X_add_number.  */
75  O_right_shift,
76  /* X_add_symbol | X_op_symbol) + X_add_number.  */
77  O_bit_inclusive_or,
78  /* X_add_symbol |~ X_op_symbol) + X_add_number.  */
79  O_bit_or_not,
80  /* X_add_symbol ^ X_op_symbol) + X_add_number.  */
81  O_bit_exclusive_or,
82  /* X_add_symbol & X_op_symbol) + X_add_number.  */
83  O_bit_and,
84  /* X_add_symbol + X_op_symbol) + X_add_number.  */
85  O_add,
86  /* X_add_symbol - X_op_symbol) + X_add_number.  */
87  O_subtract,
88  /* (X_add_symbol == X_op_symbol) + X_add_number.  */
89  O_eq,
90  /* (X_add_symbol != X_op_symbol) + X_add_number.  */
91  O_ne,
92  /* (X_add_symbol < X_op_symbol) + X_add_number.  */
93  O_lt,
94  /* (X_add_symbol <= X_op_symbol) + X_add_number.  */
95  O_le,
96  /* (X_add_symbol >= X_op_symbol) + X_add_number.  */
97  O_ge,
98  /* (X_add_symbol > X_op_symbol) + X_add_number.  */
99  O_gt,
100  /* (X_add_symbol && X_op_symbol) + X_add_number.  */
101  O_logical_and,
102  /* (X_add_symbol || X_op_symbol) + X_add_number.  */
103  O_logical_or,
104  /* X_op_symbol [ X_add_symbol ] */
105  O_index,
106  /* machine dependent operators */
107  O_md1,  O_md2,  O_md3,  O_md4,  O_md5,  O_md6,  O_md7,  O_md8,
108  O_md9,  O_md10, O_md11, O_md12, O_md13, O_md14, O_md15, O_md16,
109  /* this must be the largest value */
110  O_max
111} operatorT;
112
113typedef struct expressionS {
114  /* The main symbol.  */
115  symbolS *X_add_symbol;
116  /* The second symbol, if needed.  */
117  symbolS *X_op_symbol;
118  /* A number to add.  */
119  offsetT X_add_number;
120
121  /* The type of the expression.  We can't assume that an arbitrary
122     compiler can handle a bitfield of enum type.  FIXME: We could
123     check this using autoconf.  */
124#ifdef __GNUC__
125  operatorT X_op : 8;
126#else
127  unsigned char X_op;
128#endif
129
130  /* Non-zero if X_add_number should be regarded as unsigned.  This is
131     only valid for O_constant expressions.  It is only used when an
132     O_constant must be extended into a bignum (i.e., it is not used
133     when performing arithmetic on these values).
134     FIXME: This field is not set very reliably.  */
135  unsigned int X_unsigned : 1;
136
137  /* 7 additional bits can be defined if needed.  */
138
139  /* Machine dependent field */
140  unsigned short X_md;
141} expressionS;
142
143/* "result" should be type (expressionS *).  */
144#define expression(result) expr (0, result)
145
146/* If an expression is O_big, look here for its value. These common
147   data may be clobbered whenever expr() is called.  */
148/* Flonums returned here.  Big enough to hold most precise flonum.  */
149extern FLONUM_TYPE generic_floating_point_number;
150/* Bignums returned here.  */
151extern LITTLENUM_TYPE generic_bignum[];
152/* Number of littlenums in above.  */
153#define SIZE_OF_LARGE_NUMBER (20)
154
155typedef char operator_rankT;
156
157extern char get_symbol_end PARAMS ((void));
158extern void expr_begin PARAMS ((void));
159extern void expr_set_precedence PARAMS ((void));
160extern segT expr PARAMS ((int rank, expressionS * resultP));
161extern unsigned int get_single_number PARAMS ((void));
162extern symbolS *make_expr_symbol PARAMS ((expressionS * expressionP));
163extern int expr_symbol_where
164  PARAMS ((symbolS *, char **, unsigned int *));
165
166extern symbolS *expr_build_uconstant PARAMS ((offsetT));
167extern symbolS *expr_build_unary PARAMS ((operatorT, symbolS *));
168extern symbolS *expr_build_binary PARAMS ((operatorT, symbolS *, symbolS *));
169extern symbolS *expr_build_dot PARAMS ((void));
170