73 lines
2.6 KiB
C
73 lines
2.6 KiB
C
/* expr.h -> header file for expr.c
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Copyright (C) 1987, 1992 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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* Abbreviations (mnemonics).
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*
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* O operator
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* Q quantity, operand
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* X eXpression
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*/
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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-bar+42".
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* In other words we permit a (possibly undefined) minuend, a
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* (possibly undefined) subtrahend and an (absolute) augend.
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* RMS says this is so we can have 1-pass assembly for any compiler
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* emissions, and a 'case' statement might emit 'undefined1 - undefined2'.
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*
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* To simplify table-driven dispatch, we also have a "segment" for the
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* entire expression. That way we don't require complex reasoning about
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* whether particular components are defined; and we can change component
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* semantics without re-working all the dispatch tables in the assembler.
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* In other words the "type" of an expression is its segment.
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*/
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typedef struct
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{
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struct symbol *X_add_symbol; /* "foo", above */
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struct symbol *X_subtract_symbol; /* "bar", above */
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offsetT X_add_number; /* 42, above -- must be signed */
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/* What segment (expr type)? */
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segT X_seg;
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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 SEG_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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/* end of expr.h */
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