[deliverable/binutils-gdb.git] / gas / expr.h

/* 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 */
Commit	Line	Data
fecd2382	1	/* expr.h -> header file for expr.c
6efd877d KR	2	Copyright (C) 1987, 1992 Free Software Foundation, Inc.
6efd877d KR	3
a39116f1	4	This file is part of GAS, the GNU Assembler.
6efd877d	5
a39116f1 RP	6	GAS is free software; you can redistribute it and/or modify
	7	it under the terms of the GNU General Public License as published by
	8	the Free Software Foundation; either version 2, or (at your option)
	9	any later version.
6efd877d	10
a39116f1 RP	11	GAS is distributed in the hope that it will be useful,
	12	but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	GNU General Public License for more details.
6efd877d	15
a39116f1 RP	16	You should have received a copy of the GNU General Public License
	17	along with GAS; see the file COPYING. If not, write to
	18	the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
fecd2382 RP	19
	20	/*
	21	* Abbreviations (mnemonics).
	22	*
	23	* O operator
	24	* Q quantity, operand
	25	* X eXpression
	26	*/
	27
	28	/*
	29	* By popular demand, we define a struct to represent an expression.
	30	* This will no doubt mutate as expressions become baroque.
	31	*
	32	* Currently, we support expressions like "foo-bar+42".
	33	* In other words we permit a (possibly undefined) minuend, a
	34	* (possibly undefined) subtrahend and an (absolute) augend.
	35	* RMS says this is so we can have 1-pass assembly for any compiler
2fe8b7b0	36	* emissions, and a 'case' statement might emit 'undefined1 - undefined2'.
fecd2382 RP	37	*
	38	* To simplify table-driven dispatch, we also have a "segment" for the
	39	* entire expression. That way we don't require complex reasoning about
	40	* whether particular components are defined; and we can change component
	41	* semantics without re-working all the dispatch tables in the assembler.
	42	* In other words the "type" of an expression is its segment.
	43	*/
	44
	45	typedef struct
	46	{
85051959 ILT	47	struct symbol X_add_symbol; / "foo", above */
	48	struct symbol X_subtract_symbol; / "bar", above */
	49	offsetT X_add_number; /* 42, above -- must be signed */
2fe8b7b0 KR	50	/* What segment (expr type)? */
2fe8b7b0 KR	51	segT X_seg;
85051959	52	} expressionS;
fecd2382	53
2fe8b7b0	54	/* "result" should be type (expressionS ). /
fecd2382 RP	55	#define expression(result) expr(0,result)
fecd2382 RP	56
2fe8b7b0 KR	57	/* If an expression is SEG_BIG, look here for its value. These common
	58	data may be clobbered whenever expr() is called. */
	59	/* Flonums returned here. Big enough to hold most precise flonum. */
	60	extern FLONUM_TYPE generic_floating_point_number;
	61	/* Bignums returned here. */
	62	extern LITTLENUM_TYPE generic_bignum[];
	63	/* Number of littlenums in above. */
	64	#define SIZE_OF_LARGE_NUMBER (20)
fecd2382 RP	65
	66	typedef char operator_rankT;
	67
2fe8b7b0 KR	68	char get_symbol_end PARAMS ((void));
	69	segT expr PARAMS ((int rank, expressionS * resultP));
	70	unsigned int get_single_number PARAMS ((void));
fecd2382	71
8b228fe9	72	/* end of expr.h */