125 lines
4.4 KiB
C
125 lines
4.4 KiB
C
/* expr.h -> header file for expr.c
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Copyright (C) 1987, 1992, 1993 Free Software Foundation, Inc.
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This file is part of GAS, the GNU Assembler.
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GAS is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GAS is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GAS; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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/*
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* By popular demand, we define a struct to represent an expression.
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* This will no doubt mutate as expressions become baroque.
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*
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* Currently, we support expressions like "foo OP bar + 42". In other
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* words we permit a (possibly undefined) symbol, a (possibly
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* undefined) symbol and the operation used to combine the symbols,
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* and an (absolute) augend. RMS says this is so we can have 1-pass
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* assembly for any compiler emissions, and a 'case' statement might
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* emit 'undefined1 - undefined2'.
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*
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* The type of an expression used to be stored as a segment. That got
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* confusing because it overloaded the concept of a segment. I added
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* an operator field, instead.
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*/
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/* This is the type of an expression. The operator types are also
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used while parsing an expression.
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NOTE: This enumeration must match the op_rank array in expr.c. */
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typedef enum
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{
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/* An illegal expression. */
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O_illegal,
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/* A nonexistent expression. */
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O_absent,
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/* X_add_number (a constant expression). */
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O_constant,
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/* X_add_symbol + X_add_number. */
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O_symbol,
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/* A register (X_add_number is register number). */
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O_register,
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/* A big value. If X_add_number is negative or 0, the value is in
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generic_floating_point_number. Otherwise the value is in
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generic_bignum, and X_add_number is the number of LITTLENUMs in
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the value. */
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O_big,
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/* (- X_add_symbol) + X_add_number. */
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O_uminus,
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/* (~ X_add_symbol) + X_add_number. */
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O_bit_not,
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/* (X_add_symbol * X_op_symbol) + X_add_number. */
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O_multiply,
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/* (X_add_symbol / X_op_symbol) + X_add_number. */
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O_divide,
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/* X_add_symbol % X_op_symbol) + X_add_number. */
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O_modulus,
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/* X_add_symbol << X_op_symbol) + X_add_number. */
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O_left_shift,
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/* X_add_symbol >> X_op_symbol) + X_add_number. */
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O_right_shift,
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/* X_add_symbol | X_op_symbol) + X_add_number. */
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O_bit_inclusive_or,
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/* X_add_symbol |~ X_op_symbol) + X_add_number. */
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O_bit_or_not,
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/* X_add_symbol ^ X_op_symbol) + X_add_number. */
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O_bit_exclusive_or,
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/* X_add_symbol & X_op_symbol) + X_add_number. */
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O_bit_and,
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/* X_add_symbol + X_op_symbol) + X_add_number. */
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O_add,
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/* X_add_symbol - X_op_symbol) + X_add_number. */
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O_subtract
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} operatorT;
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typedef struct expressionS
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{
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/* The type of the expression. */
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operatorT X_op;
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/* The main symbol. */
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struct symbol *X_add_symbol;
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/* The second symbol, if needed. */
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struct symbol *X_op_symbol;
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/* A number to add. */
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offsetT X_add_number;
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/* Non-zero if X_add_number should be regarded as unsigned. This is
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only valid for O_constant expressions. It is only used when an
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O_constant must be extended into a bignum (i.e., it is not used
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when performing arithmetic on these values).
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FIXME: This field is not set very reliably.
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If we ever need more flags here, we can make them bitfields. */
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int X_unsigned;
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} expressionS;
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/* "result" should be type (expressionS *). */
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#define expression(result) expr (0, result)
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/* If an expression is O_big, look here for its value. These common
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data may be clobbered whenever expr() is called. */
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/* Flonums returned here. Big enough to hold most precise flonum. */
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extern FLONUM_TYPE generic_floating_point_number;
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/* Bignums returned here. */
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extern LITTLENUM_TYPE generic_bignum[];
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/* Number of littlenums in above. */
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#define SIZE_OF_LARGE_NUMBER (20)
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typedef char operator_rankT;
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char get_symbol_end PARAMS ((void));
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segT expr PARAMS ((int rank, expressionS * resultP));
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unsigned int get_single_number PARAMS ((void));
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symbolS *make_expr_symbol PARAMS ((expressionS * expressionP));
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/* end of expr.h */
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