db_expr.c revision 623 
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 *	$Id$
27 */
28
29/*
30 *	Author: David B. Golub, Carnegie Mellon University
31 *	Date:	7/90
32 */
33#include "param.h"
34#include "proc.h"
35#include <machine/db_machdep.h>
36#include <ddb/db_lex.h>
37#include <ddb/db_access.h>
38#include <ddb/db_command.h>
39
40boolean_t
41db_term(valuep)
42	db_expr_t *valuep;
43{
44	int	t;
45
46	t = db_read_token();
47	if (t == tIDENT) {
48	    if (!db_value_of_name(db_tok_string, valuep)) {
49		db_error("Symbol not found\n");
50		/*NOTREACHED*/
51	    }
52	    return (TRUE);
53	}
54	if (t == tNUMBER) {
55	    *valuep = (db_expr_t)db_tok_number;
56	    return (TRUE);
57	}
58	if (t == tDOT) {
59	    *valuep = (db_expr_t)db_dot;
60	    return (TRUE);
61	}
62	if (t == tDOTDOT) {
63	    *valuep = (db_expr_t)db_prev;
64	    return (TRUE);
65	}
66	if (t == tPLUS) {
67	    *valuep = (db_expr_t) db_next;
68	    return (TRUE);
69	}
70	if (t == tDITTO) {
71	    *valuep = (db_expr_t)db_last_addr;
72	    return (TRUE);
73	}
74	if (t == tDOLLAR) {
75	    if (!db_get_variable(valuep))
76		return (FALSE);
77	    return (TRUE);
78	}
79	if (t == tLPAREN) {
80	    if (!db_expression(valuep)) {
81		db_error("Syntax error\n");
82		/*NOTREACHED*/
83	    }
84	    t = db_read_token();
85	    if (t != tRPAREN) {
86		db_error("Syntax error\n");
87		/*NOTREACHED*/
88	    }
89	    return (TRUE);
90	}
91	db_unread_token(t);
92	return (FALSE);
93}
94
95boolean_t
96db_unary(valuep)
97	db_expr_t *valuep;
98{
99	int	t;
100
101	t = db_read_token();
102	if (t == tMINUS) {
103	    if (!db_unary(valuep)) {
104		db_error("Syntax error\n");
105		/*NOTREACHED*/
106	    }
107	    *valuep = -*valuep;
108	    return (TRUE);
109	}
110	if (t == tSTAR) {
111	    /* indirection */
112	    if (!db_unary(valuep)) {
113		db_error("Syntax error\n");
114		/*NOTREACHED*/
115	    }
116	    *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE);
117	    return (TRUE);
118	}
119	db_unread_token(t);
120	return (db_term(valuep));
121}
122
123boolean_t
124db_mult_expr(valuep)
125	db_expr_t *valuep;
126{
127	db_expr_t	lhs, rhs;
128	int		t;
129
130	if (!db_unary(&lhs))
131	    return (FALSE);
132
133	t = db_read_token();
134	while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) {
135	    if (!db_term(&rhs)) {
136		db_error("Syntax error\n");
137		/*NOTREACHED*/
138	    }
139	    if (t == tSTAR)
140		lhs *= rhs;
141	    else {
142		if (rhs == 0) {
143		    db_error("Divide by 0\n");
144		    /*NOTREACHED*/
145		}
146		if (t == tSLASH)
147		    lhs /= rhs;
148		else if (t == tPCT)
149		    lhs %= rhs;
150		else
151		    lhs = ((lhs+rhs-1)/rhs)*rhs;
152	    }
153	    t = db_read_token();
154	}
155	db_unread_token(t);
156	*valuep = lhs;
157	return (TRUE);
158}
159
160boolean_t
161db_add_expr(valuep)
162	db_expr_t *valuep;
163{
164	db_expr_t	lhs, rhs;
165	int		t;
166
167	if (!db_mult_expr(&lhs))
168	    return (FALSE);
169
170	t = db_read_token();
171	while (t == tPLUS || t == tMINUS) {
172	    if (!db_mult_expr(&rhs)) {
173		db_error("Syntax error\n");
174		/*NOTREACHED*/
175	    }
176	    if (t == tPLUS)
177		lhs += rhs;
178	    else
179		lhs -= rhs;
180	    t = db_read_token();
181	}
182	db_unread_token(t);
183	*valuep = lhs;
184	return (TRUE);
185}
186
187boolean_t
188db_shift_expr(valuep)
189	db_expr_t *valuep;
190{
191	db_expr_t	lhs, rhs;
192	int		t;
193
194	if (!db_add_expr(&lhs))
195	    return (FALSE);
196
197	t = db_read_token();
198	while (t == tSHIFT_L || t == tSHIFT_R) {
199	    if (!db_add_expr(&rhs)) {
200		db_error("Syntax error\n");
201		/*NOTREACHED*/
202	    }
203	    if (rhs < 0) {
204		db_error("Negative shift amount\n");
205		/*NOTREACHED*/
206	    }
207	    if (t == tSHIFT_L)
208		lhs <<= rhs;
209	    else {
210		/* Shift right is unsigned */
211		lhs = (unsigned) lhs >> rhs;
212	    }
213	    t = db_read_token();
214	}
215	db_unread_token(t);
216	*valuep = lhs;
217	return (TRUE);
218}
219
220int
221db_expression(valuep)
222	db_expr_t *valuep;
223{
224	return (db_shift_expr(valuep));
225}
226