#ifndef _EXPR_H_ #define _EXPR_H_ /* expr.h -> header file for expr.c Copyright (C) 1987 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 1, 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. */ #import "struc-symbol.h" #import "bignum.h" #import "flonum.h" /* * This table describes the use of segments as EXPRESSION types. * * X_seg X_add_symbol X_subtract_symbol X_add_number * SEG_NONE no (legal) expression * SEG_BIG * > 32 bits const. * SEG_ABSOLUTE 0 * SEG_SECT * 0 * SEG_UNKNOWN * 0 * SEG_DIFFSECT 0 * 0 * * The blank fields MUST be 0, and are nugatory. * The '0' fields MAY be 0. The '*' fields MAY NOT be 0. * * SEG_BIG: A floating point number or an integer larger than 32 bits. * For a floating point number: * X_add_number is < 0 * The result is in the global variable generic_floating_point_number. * The value in X_add_number is -'c' where c is the character that * introduced the constant. e.g. "0f6.9" will have -'f' as a * X_add_number value. * For an integer larger than 32 bits: * X_add_number > 0 * The result is in the global variable generic_bignum. * The value in X_add_number is a count of how many littlenums it * took to represent the bignum. */ typedef enum { SEG_ABSOLUTE, /* absolute */ SEG_SECT, /* normal defined section */ SEG_DIFFSECT, /* difference between symbols in sections */ SEG_UNKNOWN, /* expression involving an undefined symbol */ SEG_NONE, /* no expression */ SEG_BIG /* bigger than 32 bits constant */ } segT; extern char *seg_name[]; extern segT N_TYPE_seg[]; /* * When an expression is SEG_BIG, it is in these globals (see comments above * about SEG_BIG). This data may be clobbered whenever expr() is called. */ extern FLONUM_TYPE generic_floating_point_number; extern LITTLENUM_TYPE generic_bignum[]; #define SIZE_OF_LARGE_NUMBER (20) /* Number of littlenums in above */ /* generic_bignum which is enough to */ /* hold most precise flonum. */ /* * 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 * emmissions, 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 { symbolS *X_add_symbol; /* foo */ symbolS *X_subtract_symbol; /* bar */ long X_add_number; /* 42 (must be signed) */ segT X_seg; /* What segment (expr type) */ } expressionS; extern segT expression( expressionS *resultP); extern char get_symbol_end( void); extern segT try_to_make_absolute( expressionS *expressionP); #endif /* _EXPR_H_ */