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/* expr.h -> header file for expr.c
Copyright (C) 1987, 1992 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 2, 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, 675 Mass Ave, Cambridge, MA 02139, USA. */
/*
* Abbreviations (mnemonics).
*
* O operator
* Q quantity, operand
* X eXpression
*/
/*
* 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-bar+42".
* In other words we permit a (possibly undefined) minuend, a
* (possibly undefined) subtrahend 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'.
*
* To simplify table-driven dispatch, we also have a "segment" for the
* entire expression. That way we don't require complex reasoning about
* whether particular components are defined; and we can change component
* semantics without re-working all the dispatch tables in the assembler.
* In other words the "type" of an expression is its segment.
*/
typedef struct
{
struct symbol *X_add_symbol; /* "foo", above */
struct symbol *X_subtract_symbol; /* "bar", above */
offsetT X_add_number; /* 42, above -- must be signed */
/* What segment (expr type)? */
segT X_seg;
} expressionS;
/* "result" should be type (expressionS *). */
#define expression(result) expr(0,result)
/* If an expression is SEG_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)
typedef char operator_rankT;
char get_symbol_end PARAMS ((void));
segT expr PARAMS ((int rank, expressionS * resultP));
unsigned int get_single_number PARAMS ((void));
/* end of expr.h */
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