db_expr.c revision 5 
1/*
2 * Mach Operating System
3 * Copyright (c) 1991,1990 Carnegie Mellon University
4 * All Rights Reserved.
5 *
6 * Permission to use, copy, modify and distribute this software and its
7 * documentation is hereby granted, provided that both the copyright
8 * notice and this permission notice appear in all copies of the
9 * software, derivative works or modified versions, and any portions
10 * thereof, and that both notices appear in supporting documentation.
11 *
12 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
13 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
14 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
15 *
16 * Carnegie Mellon requests users of this software to return to
17 *
18 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
19 *  School of Computer Science
20 *  Carnegie Mellon University
21 *  Pittsburgh PA 15213-3890
22 *
23 * any improvements or extensions that they make and grant Carnegie the
24 * rights to redistribute these changes.
25 */
26/*
27 * HISTORY
28 * $Log: db_expr.c,v $
29 * Revision 1.1  1992/03/25  21:45:09  pace
30 * Initial revision
31 *
32 * Revision 2.3  91/02/05  17:06:25  mrt
33 * 	Changed to new Mach copyright
34 * 	[91/01/31  16:17:46  mrt]
35 *
36 * Revision 2.2  90/08/27  21:50:57  dbg
37 * 	Use '..' instead of '$$' for db_prev.
38 * 	Use '+' for db_next.
39 * 	[90/08/22            dbg]
40 *
41 * 	Allow repeated unary operators.
42 * 	[90/08/20            dbg]
43 *
44 * 	Reflected back rename of db_symbol_value->db_value_of_name
45 * 	[90/08/20            af]
46 * 	Reduce lint.
47 * 	[90/08/07            dbg]
48 * 	Created.
49 * 	[90/07/25            dbg]
50 *
51 */
52/*
53 *	Author: David B. Golub, Carnegie Mellon University
54 *	Date:	7/90
55 */
56#include "param.h"
57#include "proc.h"
58#include <machine/db_machdep.h>
59#include <ddb/db_lex.h>
60#include <ddb/db_access.h>
61#include <ddb/db_command.h>
62
63boolean_t
64db_term(valuep)
65	db_expr_t *valuep;
66{
67	int	t;
68
69	t = db_read_token();
70	if (t == tIDENT) {
71	    if (!db_value_of_name(db_tok_string, valuep)) {
72		db_error("Symbol not found\n");
73		/*NOTREACHED*/
74	    }
75	    return (TRUE);
76	}
77	if (t == tNUMBER) {
78	    *valuep = (db_expr_t)db_tok_number;
79	    return (TRUE);
80	}
81	if (t == tDOT) {
82	    *valuep = (db_expr_t)db_dot;
83	    return (TRUE);
84	}
85	if (t == tDOTDOT) {
86	    *valuep = (db_expr_t)db_prev;
87	    return (TRUE);
88	}
89	if (t == tPLUS) {
90	    *valuep = (db_expr_t) db_next;
91	    return (TRUE);
92	}
93	if (t == tDITTO) {
94	    *valuep = (db_expr_t)db_last_addr;
95	    return (TRUE);
96	}
97	if (t == tDOLLAR) {
98	    if (!db_get_variable(valuep))
99		return (FALSE);
100	    return (TRUE);
101	}
102	if (t == tLPAREN) {
103	    if (!db_expression(valuep)) {
104		db_error("Syntax error\n");
105		/*NOTREACHED*/
106	    }
107	    t = db_read_token();
108	    if (t != tRPAREN) {
109		db_error("Syntax error\n");
110		/*NOTREACHED*/
111	    }
112	    return (TRUE);
113	}
114	db_unread_token(t);
115	return (FALSE);
116}
117
118boolean_t
119db_unary(valuep)
120	db_expr_t *valuep;
121{
122	int	t;
123
124	t = db_read_token();
125	if (t == tMINUS) {
126	    if (!db_unary(valuep)) {
127		db_error("Syntax error\n");
128		/*NOTREACHED*/
129	    }
130	    *valuep = -*valuep;
131	    return (TRUE);
132	}
133	if (t == tSTAR) {
134	    /* indirection */
135	    if (!db_unary(valuep)) {
136		db_error("Syntax error\n");
137		/*NOTREACHED*/
138	    }
139	    *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE);
140	    return (TRUE);
141	}
142	db_unread_token(t);
143	return (db_term(valuep));
144}
145
146boolean_t
147db_mult_expr(valuep)
148	db_expr_t *valuep;
149{
150	db_expr_t	lhs, rhs;
151	int		t;
152
153	if (!db_unary(&lhs))
154	    return (FALSE);
155
156	t = db_read_token();
157	while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) {
158	    if (!db_term(&rhs)) {
159		db_error("Syntax error\n");
160		/*NOTREACHED*/
161	    }
162	    if (t == tSTAR)
163		lhs *= rhs;
164	    else {
165		if (rhs == 0) {
166		    db_error("Divide by 0\n");
167		    /*NOTREACHED*/
168		}
169		if (t == tSLASH)
170		    lhs /= rhs;
171		else if (t == tPCT)
172		    lhs %= rhs;
173		else
174		    lhs = ((lhs+rhs-1)/rhs)*rhs;
175	    }
176	    t = db_read_token();
177	}
178	db_unread_token(t);
179	*valuep = lhs;
180	return (TRUE);
181}
182
183boolean_t
184db_add_expr(valuep)
185	db_expr_t *valuep;
186{
187	db_expr_t	lhs, rhs;
188	int		t;
189
190	if (!db_mult_expr(&lhs))
191	    return (FALSE);
192
193	t = db_read_token();
194	while (t == tPLUS || t == tMINUS) {
195	    if (!db_mult_expr(&rhs)) {
196		db_error("Syntax error\n");
197		/*NOTREACHED*/
198	    }
199	    if (t == tPLUS)
200		lhs += rhs;
201	    else
202		lhs -= rhs;
203	    t = db_read_token();
204	}
205	db_unread_token(t);
206	*valuep = lhs;
207	return (TRUE);
208}
209
210boolean_t
211db_shift_expr(valuep)
212	db_expr_t *valuep;
213{
214	db_expr_t	lhs, rhs;
215	int		t;
216
217	if (!db_add_expr(&lhs))
218	    return (FALSE);
219
220	t = db_read_token();
221	while (t == tSHIFT_L || t == tSHIFT_R) {
222	    if (!db_add_expr(&rhs)) {
223		db_error("Syntax error\n");
224		/*NOTREACHED*/
225	    }
226	    if (rhs < 0) {
227		db_error("Negative shift amount\n");
228		/*NOTREACHED*/
229	    }
230	    if (t == tSHIFT_L)
231		lhs <<= rhs;
232	    else {
233		/* Shift right is unsigned */
234		lhs = (unsigned) lhs >> rhs;
235	    }
236	    t = db_read_token();
237	}
238	db_unread_token(t);
239	*valuep = lhs;
240	return (TRUE);
241}
242
243int
244db_expression(valuep)
245	db_expr_t *valuep;
246{
247	return (db_shift_expr(valuep));
248}
249