/* expr.h -> header file for expr.c
Copyright (C) 1987-2024 Free Software Foundation, Inc.
This file is part of GAS, the GNU Assembler.
GAS is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GAS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GAS; see the file COPYING. If not, write to the Free
Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
02110-1301, USA. */
/* By popular demand, we define a struct to represent an expression.
This will no doubt mutate as expressions become baroque.
Currently, we support expressions like "foo OP bar + 42". In other
words we permit a (possibly undefined) symbol, a (possibly
undefined) symbol and the operation used to combine the symbols,
and an (absolute) augend. RMS says this is so we can have 1-pass
assembly for any compiler emissions, and a 'case' statement might
emit 'undefined1 - undefined2'.
The type of an expression used to be stored as a segment. That got
confusing because it overloaded the concept of a segment. I added
an operator field, instead. */
/* This is the type of an expression. The operator types are also
used while parsing an expression.
NOTE: This enumeration must match the op_rank array in expr.c. */
typedef enum
{
/* An illegal expression. */
O_illegal,
/* A nonexistent expression. */
O_absent,
/* X_add_number (a constant expression). */
O_constant,
/* X_add_symbol + X_add_number. */
O_symbol,
/* X_add_symbol + X_add_number - the base address of the image. */
O_symbol_rva,
/* The section index of X_add_symbol. */
O_secidx,
/* A register (X_add_number is register number). */
O_register,
/* A big value. If X_add_number is negative or 0, the value is in
generic_floating_point_number. Otherwise the value is in
generic_bignum, and X_add_number is the number of LITTLENUMs in
the value. */
O_big,
/* (- X_add_symbol) + X_add_number. */
O_uminus,
/* (~ X_add_symbol) + X_add_number. */
O_bit_not,
/* (! X_add_symbol) + X_add_number. */
O_logical_not,
/* (X_add_symbol * X_op_symbol) + X_add_number. */
O_multiply,
/* (X_add_symbol / X_op_symbol) + X_add_number. */
O_divide,
/* (X_add_symbol % X_op_symbol) + X_add_number. */
O_modulus,
/* (X_add_symbol << X_op_symbol) + X_add_number. */
O_left_shift,
/* (X_add_symbol >> X_op_symbol) + X_add_number. */
O_right_shift,
/* (X_add_symbol | X_op_symbol) + X_add_number. */
O_bit_inclusive_or,
/* (X_add_symbol |~ X_op_symbol) + X_add_number. */
O_bit_or_not,
/* (X_add_symbol ^ X_op_symbol) + X_add_number. */
O_bit_exclusive_or,
/* (X_add_symbol & X_op_symbol) + X_add_number. */
O_bit_and,
/* (X_add_symbol + X_op_symbol) + X_add_number. */
O_add,
/* (X_add_symbol - X_op_symbol) + X_add_number. */
O_subtract,
/* (X_add_symbol == X_op_symbol) + X_add_number. */
O_eq,
/* (X_add_symbol != X_op_symbol) + X_add_number. */
O_ne,
/* (X_add_symbol < X_op_symbol) + X_add_number. */
O_lt,
/* (X_add_symbol <= X_op_symbol) + X_add_number. */
O_le,
/* (X_add_symbol >= X_op_symbol) + X_add_number. */
O_ge,
/* (X_add_symbol > X_op_symbol) + X_add_number. */
O_gt,
/* (X_add_symbol && X_op_symbol) + X_add_number. */
O_logical_and,
/* (X_add_symbol || X_op_symbol) + X_add_number. */
O_logical_or,
/* X_op_symbol [ X_add_symbol ] */
O_index,
/* machine dependent operators */
O_md1, O_md2, O_md3, O_md4, O_md5, O_md6, O_md7, O_md8,
O_md9, O_md10, O_md11, O_md12, O_md13, O_md14, O_md15, O_md16,
O_md17, O_md18, O_md19, O_md20, O_md21, O_md22, O_md23, O_md24,
O_md25, O_md26, O_md27, O_md28, O_md29, O_md30, O_md31, O_md32,
/* this must be the largest value */
O_max
} operatorT;
typedef struct expressionS
{
/* The main symbol. */
symbolS *X_add_symbol;
/* The second symbol, if needed. */
symbolS *X_op_symbol;
/* A number to add. */
offsetT X_add_number;
/* The type of the expression. We can't assume that an arbitrary
compiler can handle a bitfield of enum type. FIXME: We could
check this using autoconf. */
#ifdef __GNUC__
operatorT X_op : 8;
#else
unsigned char X_op;
#endif
/* Non-zero if X_add_number should be regarded as unsigned. This is
only valid for O_constant expressions. It is only used when an
O_constant must be extended into a bignum (i.e., it is not used
when performing arithmetic on these values).
FIXME: This field is not set very reliably. */
unsigned int X_unsigned : 1;
/* This is used to implement "word size + 1 bit" arithmetic, so that e.g.
expressions used with .sleb128 directives can use the full range available
for an unsigned word, but can also properly represent all values of a
signed word. */
unsigned int X_extrabit : 1;
/* 7 additional bits can be defined if needed. */
/* Machine dependent field */
unsigned short X_md;
} expressionS;
/* "result" should be type (expressionS *). */
#define expression(result) expr (0, result, expr_normal)
#define expression_and_evaluate(result) expr (0, result, expr_evaluate)
#define deferred_expression(result) expr (0, result, expr_defer)
/* If an expression is O_big, look here for its value. These common
data may be clobbered whenever expr() is called. */
/* Flonums returned here. Big enough to hold most precise flonum. */
extern FLONUM_TYPE generic_floating_point_number;
/* Bignums returned here. */
extern LITTLENUM_TYPE generic_bignum[];
/* Number of littlenums in above. */
#define SIZE_OF_LARGE_NUMBER (20)
