3a69b3ac |
1 | /* expr.h -> header file for expr.c |
2 | Copyright (C) 1987 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 1, 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 |
18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ |
19 | |
20 | /* |
21 | * Abbreviations (mnemonics). |
22 | * |
23 | * O operator |
24 | * Q quantity, operand |
25 | * X eXpression |
26 | */ |
27 | |
28 | /* |
29 | * By popular demand, we define a struct to represent an expression. |
30 | * This will no doubt mutate as expressions become baroque. |
31 | * |
32 | * Currently, we support expressions like "foo-bar+42". |
33 | * In other words we permit a (possibly undefined) minuend, a |
34 | * (possibly undefined) subtrahend and an (absolute) augend. |
35 | * RMS says this is so we can have 1-pass assembly for any compiler |
36 | * emmissions, and a 'case' statement might emit 'undefined1 - undefined2'. |
37 | * |
38 | * To simplify table-driven dispatch, we also have a "segment" for the |
39 | * entire expression. That way we don't require complex reasoning about |
40 | * whether particular components are defined; and we can change component |
41 | * semantics without re-working all the dispatch tables in the assembler. |
42 | * In other words the "type" of an expression is its segment. |
43 | */ |
44 | |
45 | typedef struct |
46 | { |
47 | symbolS *X_add_symbol; /* foo */ |
48 | symbolS *X_subtract_symbol; /* bar */ |
49 | long X_add_number; /* 42. Must be signed. */ |
50 | segT X_seg; /* What segment (expr type)? */ |
51 | } |
52 | expressionS; |
53 | |
54 | /* result should be type (expressionS *). */ |
55 | #define expression(result) expr(0,result) |
56 | |
57 | /* If an expression is SEG_BIG, look here */ |
58 | /* for its value. These common data may */ |
59 | /* be clobbered whenever expr() is called. */ |
60 | extern FLONUM_TYPE generic_floating_point_number; /* Flonums returned here. */ |
61 | /* Enough to hold most precise flonum. */ |
62 | extern LITTLENUM_TYPE generic_bignum []; /* Bignums returned here. */ |
63 | #define SIZE_OF_LARGE_NUMBER (20) /* Number of littlenums in above. */ |
64 | |
65 | typedef char operator_rankT; |
66 | |
67 | #ifdef __STDC__ |
68 | |
69 | char get_symbol_end(void); |
70 | segT expr(int rank, expressionS *resultP); |
71 | |
72 | #else /* __STDC__ */ |
73 | |
74 | char get_symbol_end(); |
75 | segT expr(); |
76 | |
77 | #endif /* __STDC__ */ |
78 | |
79 | /* end: expr.h */ |