| 1 | /* expr.h -> header file for expr.c
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| 2 | Copyright 1987, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000
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| 3 | Free Software Foundation, Inc.
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| 4 |
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| 5 | This file is part of GAS, the GNU Assembler.
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| 6 |
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| 7 | GAS is free software; you can redistribute it and/or modify
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| 8 | it under the terms of the GNU General Public License as published by
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| 9 | the Free Software Foundation; either version 2, or (at your option)
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| 10 | any later version.
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| 11 |
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| 12 | GAS is distributed in the hope that it will be useful,
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| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 15 | GNU General Public License for more details.
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| 16 |
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| 17 | You should have received a copy of the GNU General Public License
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| 18 | along with GAS; see the file COPYING. If not, write to the Free
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| 19 | Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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| 20 | 02111-1307, USA. */
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| 21 |
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| 22 | /*
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| 23 | * By popular demand, we define a struct to represent an expression.
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| 24 | * This will no doubt mutate as expressions become baroque.
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| 25 | *
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| 26 | * Currently, we support expressions like "foo OP bar + 42". In other
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| 27 | * words we permit a (possibly undefined) symbol, a (possibly
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| 28 | * undefined) symbol and the operation used to combine the symbols,
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| 29 | * and an (absolute) augend. RMS says this is so we can have 1-pass
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| 30 | * assembly for any compiler emissions, and a 'case' statement might
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| 31 | * emit 'undefined1 - undefined2'.
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| 32 | *
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| 33 | * The type of an expression used to be stored as a segment. That got
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| 34 | * confusing because it overloaded the concept of a segment. I added
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| 35 | * an operator field, instead.
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| 36 | */
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| 37 |
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| 38 | /* This is the type of an expression. The operator types are also
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| 39 | used while parsing an expression.
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| 40 |
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| 41 | NOTE: This enumeration must match the op_rank array in expr.c. */
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| 42 |
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| 43 | typedef enum {
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| 44 | /* An illegal expression. */
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| 45 | O_illegal,
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| 46 | /* A nonexistent expression. */
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| 47 | O_absent,
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| 48 | /* X_add_number (a constant expression). */
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| 49 | O_constant,
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| 50 | /* X_add_symbol + X_add_number. */
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| 51 | O_symbol,
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| 52 | /* X_add_symbol + X_add_number - the base address of the image. */
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| 53 | O_symbol_rva,
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| 54 | /* A register (X_add_number is register number). */
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| 55 | O_register,
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| 56 | /* A big value. If X_add_number is negative or 0, the value is in
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| 57 | generic_floating_point_number. Otherwise the value is in
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| 58 | generic_bignum, and X_add_number is the number of LITTLENUMs in
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| 59 | the value. */
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| 60 | O_big,
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| 61 | /* (- X_add_symbol) + X_add_number. */
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| 62 | O_uminus,
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| 63 | /* (~ X_add_symbol) + X_add_number. */
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| 64 | O_bit_not,
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| 65 | /* (! X_add_symbol) + X_add_number. */
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| 66 | O_logical_not,
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| 67 | /* (X_add_symbol * X_op_symbol) + X_add_number. */
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| 68 | O_multiply,
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| 69 | /* (X_add_symbol / X_op_symbol) + X_add_number. */
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| 70 | O_divide,
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| 71 | /* (X_add_symbol % X_op_symbol) + X_add_number. */
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| 72 | O_modulus,
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| 73 | /* (X_add_symbol << X_op_symbol) + X_add_number. */
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