| 1 | /* expr.h -> header file for expr.c |
| 2 | Copyright (C) 1987, 1992, 1993 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 |
| 18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ |
| 19 | |
| 20 | /* |
| 21 | * By popular demand, we define a struct to represent an expression. |
| 22 | * This will no doubt mutate as expressions become baroque. |
| 23 | * |
| 24 | * Currently, we support expressions like "foo OP bar + 42". In other |
| 25 | * words we permit a (possibly undefined) symbol, a (possibly |
| 26 | * undefined) symbol and the operation used to combine the symbols, |
| 27 | * and an (absolute) augend. RMS says this is so we can have 1-pass |
| 28 | * assembly for any compiler emissions, and a 'case' statement might |
| 29 | * emit 'undefined1 - undefined2'. |
| 30 | * |
| 31 | * The type of an expression used to be stored as a segment. That got |
| 32 | * confusing because it overloaded the concept of a segment. I added |
| 33 | * an operator field, instead. |
| 34 | */ |
| 35 | |
| 36 | /* This is the type of an expression. The operator types are also |
| 37 | used while parsing an expression. |
| 38 | |
| 39 | NOTE: This enumeration must match the op_rank array in expr.c. */ |
| 40 | |
| 41 | typedef enum |
| 42 | { |
| 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 | /* A register (X_add_number is register number). */ |
| 52 | O_register, |
| 53 | /* A big value. If X_add_number is negative or 0, the value is in |
| 54 | generic_floating_point_number. Otherwise the value is in |
| 55 | generic_bignum, and X_add_number is the number of LITTLENUMs in |
| 56 | the value. */ |
| 57 | O_big, |
| 58 | /* (- X_add_symbol) + X_add_number. */ |
| 59 | O_uminus, |
| 60 | /* (~ X_add_symbol) + X_add_number. */ |
| 61 | O_bit_not, |
| 62 | /* (X_add_symbol * X_op_symbol) + X_add_number. */ |
| 63 | O_multiply, |
| 64 | /* (X_add_symbol / X_op_symbol) + X_add_number. */ |
| 65 | O_divide, |
| 66 | /* X_add_symbol % X_op_symbol) + X_add_number. */ |
| 67 | O_modulus, |
| 68 | /* X_add_symbol << X_op_symbol) + X_add_number. */ |
| 69 | O_left_shift, |
| 70 | /* X_add_symbol >> X_op_symbol) + X_add_number. */ |
| 71 | O_right_shift, |
| 72 | /* X_add_symbol | X_op_symbol) + X_add_number. */ |
| 73 | O_bit_inclusive_or, |
| 74 | /* X_add_symbol |~ X_op_symbol) + X_add_number. */ |
| 75 | O_bit_or_not, |
| 76 | /* X_add_symbol ^ X_op_symbol) + X_add_number. */ |
| 77 | O_bit_exclusive_or, |
| 78 | /* X_add_symbol & X_op_symbol) + X_add_number. */ |
| 79 | O_bit_and, |
| 80 | /* X_add_symbol + X_op_symbol) + X_add_number. */ |
| 81 | O_add, |
| 82 | /* X_add_symbol - X_op_symbol) + X_add_number. */ |
| 83 | O_subtract |
| 84 | } operatorT; |
| 85 | |
| 86 | typedef struct expressionS |
| 87 | { |
| 88 | /* The type of the expression. */ |
| 89 | operatorT X_op; |
| 90 | /* The main symbol. */ |
| 91 | struct symbol *X_add_symbol; |
| 92 | /* The second symbol, if needed. */ |
| 93 | struct symbol *X_op_symbol; |
| 94 | /* A number to add. */ |
| 95 | offsetT X_add_number; |
| 96 | /* Non-zero if X_add_number should be regarded as unsigned. This is |
| 97 | only valid for O_constant expressions. It is only used when an |
| 98 | O_constant must be extended into a bignum (i.e., it is not used |
| 99 | when performing arithmetic on these values). |
| 100 | FIXME: This field is not set very reliably. |
| 101 | If we ever need more flags here, we can make them bitfields. */ |
| 102 | int X_unsigned; |
| 103 | } expressionS; |
| 104 | |
| 105 | /* "result" should be type (expressionS *). */ |
| 106 | #define expression(result) expr (0, result) |
| 107 | |
| 108 | /* If an expression is O_big, look here for its value. These common |
| 109 | data may be clobbered whenever expr() is called. */ |
| 110 | /* Flonums returned here. Big enough to hold most precise flonum. */ |
| 111 | extern FLONUM_TYPE generic_floating_point_number; |
| 112 | /* Bignums returned here. */ |
| 113 | extern LITTLENUM_TYPE generic_bignum[]; |
| 114 | /* Number of littlenums in above. */ |
| 115 | #define SIZE_OF_LARGE_NUMBER (20) |
| 116 | |
| 117 | typedef char operator_rankT; |
| 118 | |
| 119 | char get_symbol_end PARAMS ((void)); |
| 120 | segT expr PARAMS ((int rank, expressionS * resultP)); |
| 121 | unsigned int get_single_number PARAMS ((void)); |
| 122 | symbolS *make_expr_symbol PARAMS ((expressionS * expressionP)); |
| 123 | |
| 124 | /* end of expr.h */ |