db_expr.c revision 12662 
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 *	$Id: db_expr.c,v 1.7 1995/11/29 10:25:18 phk Exp $
27 */
28
29/*
30 *	Author: David B. Golub, Carnegie Mellon University
31 *	Date:	7/90
32 */
33#include <sys/param.h>
34#include <sys/systm.h>
35#include <sys/proc.h>
36#include <vm/vm_param.h>
37#include <ddb/ddb.h>
38#include <ddb/db_lex.h>
39#include <ddb/db_access.h>
40#include <ddb/db_command.h>
41
42static boolean_t	db_add_expr __P((db_expr_t *valuep));
43static boolean_t	db_mult_expr __P((db_expr_t *valuep));
44static boolean_t	db_shift_expr __P((db_expr_t *valuep));
45static boolean_t	db_term __P((db_expr_t *valuep));
46static boolean_t	db_unary __P((db_expr_t *valuep));
47
48static boolean_t
49db_term(valuep)
50	db_expr_t *valuep;
51{
52	int	t;
53
54	t = db_read_token();
55	if (t == tIDENT) {
56	    if (!db_value_of_name(db_tok_string, valuep)) {
57		db_error("Symbol not found\n");
58		/*NOTREACHED*/
59	    }
60	    return (TRUE);
61	}
62	if (t == tNUMBER) {
63	    *valuep = (db_expr_t)db_tok_number;
64	    return (TRUE);
65	}
66	if (t == tDOT) {
67	    *valuep = (db_expr_t)db_dot;
68	    return (TRUE);
69	}
70	if (t == tDOTDOT) {
71	    *valuep = (db_expr_t)db_prev;
72	    return (TRUE);
73	}
74	if (t == tPLUS) {
75	    *valuep = (db_expr_t) db_next;
76	    return (TRUE);
77	}
78	if (t == tDITTO) {
79	    *valuep = (db_expr_t)db_last_addr;
80	    return (TRUE);
81	}
82	if (t == tDOLLAR) {
83	    if (!db_get_variable(valuep))
84		return (FALSE);
85	    return (TRUE);
86	}
87	if (t == tLPAREN) {
88	    if (!db_expression(valuep)) {
89		db_error("Syntax error\n");
90		/*NOTREACHED*/
91	    }
92	    t = db_read_token();
93	    if (t != tRPAREN) {
94		db_error("Syntax error\n");
95		/*NOTREACHED*/
96	    }
97	    return (TRUE);
98	}
99	db_unread_token(t);
100	return (FALSE);
101}
102
103static boolean_t
104db_unary(valuep)
105	db_expr_t *valuep;
106{
107	int	t;
108
109	t = db_read_token();
110	if (t == tMINUS) {
111	    if (!db_unary(valuep)) {
112		db_error("Syntax error\n");
113		/*NOTREACHED*/
114	    }
115	    *valuep = -*valuep;
116	    return (TRUE);
117	}
118	if (t == tSTAR) {
119	    /* indirection */
120	    if (!db_unary(valuep)) {
121		db_error("Syntax error\n");
122		/*NOTREACHED*/
123	    }
124	    *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE);
125	    return (TRUE);
126	}
127	db_unread_token(t);
128	return (db_term(valuep));
129}
130
131static boolean_t
132db_mult_expr(valuep)
133	db_expr_t *valuep;
134{
135	db_expr_t	lhs, rhs;
136	int		t;
137
138	if (!db_unary(&lhs))
139	    return (FALSE);
140
141	t = db_read_token();
142	while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) {
143	    if (!db_term(&rhs)) {
144		db_error("Syntax error\n");
145		/*NOTREACHED*/
146	    }
147	    if (t == tSTAR)
148		lhs *= rhs;
149	    else {
150		if (rhs == 0) {
151		    db_error("Divide by 0\n");
152		    /*NOTREACHED*/
153		}
154		if (t == tSLASH)
155		    lhs /= rhs;
156		else if (t == tPCT)
157		    lhs %= rhs;
158		else
159		    lhs = ((lhs+rhs-1)/rhs)*rhs;
160	    }
161	    t = db_read_token();
162	}
163	db_unread_token(t);
164	*valuep = lhs;
165	return (TRUE);
166}
167
168static boolean_t
169db_add_expr(valuep)
170	db_expr_t *valuep;
171{
172	db_expr_t	lhs, rhs;
173	int		t;
174
175	if (!db_mult_expr(&lhs))
176	    return (FALSE);
177
178	t = db_read_token();
179	while (t == tPLUS || t == tMINUS) {
180	    if (!db_mult_expr(&rhs)) {
181		db_error("Syntax error\n");
182		/*NOTREACHED*/
183	    }
184	    if (t == tPLUS)
185		lhs += rhs;
186	    else
187		lhs -= rhs;
188	    t = db_read_token();
189	}
190	db_unread_token(t);
191	*valuep = lhs;
192	return (TRUE);
193}
194
195static boolean_t
196db_shift_expr(valuep)
197	db_expr_t *valuep;
198{
199	db_expr_t	lhs, rhs;
200	int		t;
201
202	if (!db_add_expr(&lhs))
203	    return (FALSE);
204
205	t = db_read_token();
206	while (t == tSHIFT_L || t == tSHIFT_R) {
207	    if (!db_add_expr(&rhs)) {
208		db_error("Syntax error\n");
209		/*NOTREACHED*/
210	    }
211	    if (rhs < 0) {
212		db_error("Negative shift amount\n");
213		/*NOTREACHED*/
214	    }
215	    if (t == tSHIFT_L)
216		lhs <<= rhs;
217	    else {
218		/* Shift right is unsigned */
219		lhs = (unsigned) lhs >> rhs;
220	    }
221	    t = db_read_token();
222	}
223	db_unread_token(t);
224	*valuep = lhs;
225	return (TRUE);
226}
227
228int
229db_expression(valuep)
230	db_expr_t *valuep;
231{
232	return (db_shift_expr(valuep));
233}
234