[binutils.git] / gas / 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.  */

/*
 * 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;

				/* 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. */
extern FLONUM_TYPE generic_floating_point_number; /* Flonums returned here. */
				/* Enough to hold most precise flonum. */
extern LITTLENUM_TYPE generic_bignum []; /* Bignums returned here. */
#define SIZE_OF_LARGE_NUMBER (20)	/* Number of littlenums in above. */

typedef char operator_rankT;

#ifdef __STDC__

char get_symbol_end(void);
segT expr(int rank, expressionS *resultP);

#else /* __STDC__ */

char get_symbol_end();
segT expr();

#endif /* __STDC__ */

/* end: expr.h */
Commit	Line	Data
fecd2382 RP	1	/* expr.h -> header file for expr.c
	2	Copyright (C) 1987 Free Software Foundation, Inc.
	3
	4	This file is part of GAS, the GNU Assembler.
	5
	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 1, or (at your option)
	9	any later version.
	10
	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.
	15
	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. */
	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
	36	* emmissions, and a 'case' statement might emit 'undefined1 - undefined2'.
	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	{
	47	symbolS X_add_symbol; / foo */
	48	symbolS X_subtract_symbol; / bar */
	49	long X_add_number; /* 42. Must be signed. */
	50	segT X_seg; /* What segment (expr type)? */
	51	}
	52	expressionS;
	53
	54	/* result should be type (expressionS ). /
	55	#define expression(result) expr(0,result)
	56
	57	/* If an expression is SEG_BIG, look here */
	58	/* for its value. These common data may */
	59	/* be clobbered whenever expr() is called. */
	60	extern FLONUM_TYPE generic_floating_point_number; /* Flonums returned here. */
	61	/* Enough to hold most precise flonum. */
	62	extern LITTLENUM_TYPE generic_bignum []; /* Bignums returned here. */
	63	#define SIZE_OF_LARGE_NUMBER (20) /* Number of littlenums in above. */
	64
65	typedef char operator_rankT;
66
67	#ifdef __STDC__
68
69	char get_symbol_end(void);
70	segT expr(int rank, expressionS *resultP);
71
72	#else /* __STDC__ */
73
74	char get_symbol_end();
75	segT expr();
76
77	#endif /* __STDC__ */
78
79	/* end: expr.h */