db_expr.c revision 92756 
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 * $FreeBSD: head/sys/ddb/db_expr.c 92756 2002-03-20 05:14:42Z alfred $
27 */
28
29/*
30 *	Author: David B. Golub, Carnegie Mellon University
31 *	Date:	7/90
32 */
33#include <sys/param.h>
34
35#include <ddb/ddb.h>
36#include <ddb/db_lex.h>
37#include <ddb/db_access.h>
38#include <ddb/db_command.h>
39
40static boolean_t	db_add_expr(db_expr_t *valuep);
41static boolean_t	db_mult_expr(db_expr_t *valuep);
42static boolean_t	db_shift_expr(db_expr_t *valuep);
43static boolean_t	db_term(db_expr_t *valuep);
44static boolean_t	db_unary(db_expr_t *valuep);
45
46static boolean_t
47db_term(valuep)
48	db_expr_t *valuep;
49{
50	int	t;
51
52	t = db_read_token();
53	if (t == tIDENT) {
54	    if (!db_value_of_name(db_tok_string, valuep)) {
55		db_error("Symbol not found\n");
56		/*NOTREACHED*/
57	    }
58	    return (TRUE);
59	}
60	if (t == tNUMBER) {
61	    *valuep = (db_expr_t)db_tok_number;
62	    return (TRUE);
63	}
64	if (t == tDOT) {
65	    *valuep = (db_expr_t)db_dot;
66	    return (TRUE);
67	}
68	if (t == tDOTDOT) {
69	    *valuep = (db_expr_t)db_prev;
70	    return (TRUE);
71	}
72	if (t == tPLUS) {
73	    *valuep = (db_expr_t) db_next;
74	    return (TRUE);
75	}
76	if (t == tDITTO) {
77	    *valuep = (db_expr_t)db_last_addr;
78	    return (TRUE);
79	}
80	if (t == tDOLLAR) {
81	    if (!db_get_variable(valuep))
82		return (FALSE);
83	    return (TRUE);
84	}
85	if (t == tLPAREN) {
86	    if (!db_expression(valuep)) {
87		db_error("Syntax error\n");
88		/*NOTREACHED*/
89	    }
90	    t = db_read_token();
91	    if (t != tRPAREN) {
92		db_error("Syntax error\n");
93		/*NOTREACHED*/
94	    }
95	    return (TRUE);
96	}
97	db_unread_token(t);
98	return (FALSE);
99}
100
101static boolean_t
102db_unary(valuep)
103	db_expr_t *valuep;
104{
105	int	t;
106
107	t = db_read_token();
108	if (t == tMINUS) {
109	    if (!db_unary(valuep)) {
110		db_error("Syntax error\n");
111		/*NOTREACHED*/
112	    }
113	    *valuep = -*valuep;
114	    return (TRUE);
115	}
116	if (t == tSTAR) {
117	    /* indirection */
118	    if (!db_unary(valuep)) {
119		db_error("Syntax error\n");
120		/*NOTREACHED*/
121	    }
122	    *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE);
123	    return (TRUE);
124	}
125	db_unread_token(t);
126	return (db_term(valuep));
127}
128
129static boolean_t
130db_mult_expr(valuep)
131	db_expr_t *valuep;
132{
133	db_expr_t	lhs, rhs;
134	int		t;
135
136	if (!db_unary(&lhs))
137	    return (FALSE);
138
139	t = db_read_token();
140	while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) {
141	    if (!db_term(&rhs)) {
142		db_error("Syntax error\n");
143		/*NOTREACHED*/
144	    }
145	    if (t == tSTAR)
146		lhs *= rhs;
147	    else {
148		if (rhs == 0) {
149		    db_error("Divide by 0\n");
150		    /*NOTREACHED*/
151		}
152		if (t == tSLASH)
153		    lhs /= rhs;
154		else if (t == tPCT)
155		    lhs %= rhs;
156		else
157		    lhs = ((lhs+rhs-1)/rhs)*rhs;
158	    }
159	    t = db_read_token();
160	}
161	db_unread_token(t);
162	*valuep = lhs;
163	return (TRUE);
164}
165
166static boolean_t
167db_add_expr(valuep)
168	db_expr_t *valuep;
169{
170	db_expr_t	lhs, rhs;
171	int		t;
172
173	if (!db_mult_expr(&lhs))
174	    return (FALSE);
175
176	t = db_read_token();
177	while (t == tPLUS || t == tMINUS) {
178	    if (!db_mult_expr(&rhs)) {
179		db_error("Syntax error\n");
180		/*NOTREACHED*/
181	    }
182	    if (t == tPLUS)
183		lhs += rhs;
184	    else
185		lhs -= rhs;
186	    t = db_read_token();
187	}
188	db_unread_token(t);
189	*valuep = lhs;
190	return (TRUE);
191}
192
193static boolean_t
194db_shift_expr(valuep)
195	db_expr_t *valuep;
196{
197	db_expr_t	lhs, rhs;
198	int		t;
199
200	if (!db_add_expr(&lhs))
201	    return (FALSE);
202
203	t = db_read_token();
204	while (t == tSHIFT_L || t == tSHIFT_R) {
205	    if (!db_add_expr(&rhs)) {
206		db_error("Syntax error\n");
207		/*NOTREACHED*/
208	    }
209	    if (rhs < 0) {
210		db_error("Negative shift amount\n");
211		/*NOTREACHED*/
212	    }
213	    if (t == tSHIFT_L)
214		lhs <<= rhs;
215	    else {
216		/* Shift right is unsigned */
217		lhs = (unsigned) lhs >> rhs;
218	    }
219	    t = db_read_token();
220	}
221	db_unread_token(t);
222	*valuep = lhs;
223	return (TRUE);
224}
225
226int
227db_expression(valuep)
228	db_expr_t *valuep;
229{
230	return (db_shift_expr(valuep));
231}
232