70 lines
2.4 KiB
C
70 lines
2.4 KiB
C
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/* expr.h -> header file for expr.c
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Copyright (C) 1987 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 1, 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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* emmissions, 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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symbolS *X_add_symbol; /* foo */
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symbolS *X_subtract_symbol; /* bar */
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long int X_add_number; /* 42. Must be signed. */
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segT X_seg; /* What segment (expr type)? */
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}
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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 */
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/* for its value. These common data may */
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/* be clobbered whenever expr() is called. */
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extern FLONUM_TYPE generic_floating_point_number; /* Flonums returned here. */
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/* Enough to hold most precise flonum. */
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extern LITTLENUM_TYPE generic_bignum []; /* Bignums returned here. */
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#define SIZE_OF_LARGE_NUMBER (20) /* Number of littlenums in above. */
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segT expr();
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char get_symbol_end();
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/* end: expr.h */
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