FreeBSD/Linux Kernel Cross Reference
sys/ddb/db_expr.c
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 * Author: David B. Golub, Carnegie Mellon University
28 * Date: 7/90
29 */
30
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD: src/sys/ddb/db_expr.c,v 1.17 2005/01/06 01:34:41 imp Exp $");
33
34 #include <sys/param.h>
35
36 #include <ddb/ddb.h>
37 #include <ddb/db_lex.h>
38 #include <ddb/db_access.h>
39 #include <ddb/db_command.h>
40
41 static boolean_t db_add_expr(db_expr_t *valuep);
42 static boolean_t db_mult_expr(db_expr_t *valuep);
43 static boolean_t db_shift_expr(db_expr_t *valuep);
44 static boolean_t db_term(db_expr_t *valuep);
45 static boolean_t db_unary(db_expr_t *valuep);
46
47 static boolean_t
48 db_term(valuep)
49 db_expr_t *valuep;
50 {
51 int t;
52
53 t = db_read_token();
54 if (t == tIDENT) {
55 if (!db_value_of_name(db_tok_string, valuep)) {
56 db_error("Symbol not found\n");
57 /*NOTREACHED*/
58 }
59 return (TRUE);
60 }
61 if (t == tNUMBER) {
62 *valuep = (db_expr_t)db_tok_number;
63 return (TRUE);
64 }
65 if (t == tDOT) {
66 *valuep = (db_expr_t)db_dot;
67 return (TRUE);
68 }
69 if (t == tDOTDOT) {
70 *valuep = (db_expr_t)db_prev;
71 return (TRUE);
72 }
73 if (t == tPLUS) {
74 *valuep = (db_expr_t) db_next;
75 return (TRUE);
76 }
77 if (t == tDITTO) {
78 *valuep = (db_expr_t)db_last_addr;
79 return (TRUE);
80 }
81 if (t == tDOLLAR) {
82 if (!db_get_variable(valuep))
83 return (FALSE);
84 return (TRUE);
85 }
86 if (t == tLPAREN) {
87 if (!db_expression(valuep)) {
88 db_error("Syntax error\n");
89 /*NOTREACHED*/
90 }
91 t = db_read_token();
92 if (t != tRPAREN) {
93 db_error("Syntax error\n");
94 /*NOTREACHED*/
95 }
96 return (TRUE);
97 }
98 db_unread_token(t);
99 return (FALSE);
100 }
101
102 static boolean_t
103 db_unary(valuep)
104 db_expr_t *valuep;
105 {
106 int t;
107
108 t = db_read_token();
109 if (t == tMINUS) {
110 if (!db_unary(valuep)) {
111 db_error("Syntax error\n");
112 /*NOTREACHED*/
113 }
114 *valuep = -*valuep;
115 return (TRUE);
116 }
117 if (t == tSTAR) {
118 /* indirection */
119 if (!db_unary(valuep)) {
120 db_error("Syntax error\n");
121 /*NOTREACHED*/
122 }
123 *valuep = db_get_value((db_addr_t)*valuep, sizeof(void *), FALSE);
124 return (TRUE);
125 }
126 db_unread_token(t);
127 return (db_term(valuep));
128 }
129
130 static boolean_t
131 db_mult_expr(valuep)
132 db_expr_t *valuep;
133 {
134 db_expr_t lhs, rhs;
135 int t;
136
137 if (!db_unary(&lhs))
138 return (FALSE);
139
140 t = db_read_token();
141 while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) {
142 if (!db_term(&rhs)) {
143 db_error("Syntax error\n");
144 /*NOTREACHED*/
145 }
146 if (t == tSTAR)
147 lhs *= rhs;
148 else {
149 if (rhs == 0) {
150 db_error("Divide by 0\n");
151 /*NOTREACHED*/
152 }
153 if (t == tSLASH)
154 lhs /= rhs;
155 else if (t == tPCT)
156 lhs %= rhs;
157 else
158 lhs = ((lhs+rhs-1)/rhs)*rhs;
159 }
160 t = db_read_token();
161 }
162 db_unread_token(t);
163 *valuep = lhs;
164 return (TRUE);
165 }
166
167 static boolean_t
168 db_add_expr(valuep)
169 db_expr_t *valuep;
170 {
171 db_expr_t lhs, rhs;
172 int t;
173
174 if (!db_mult_expr(&lhs))
175 return (FALSE);
176
177 t = db_read_token();
178 while (t == tPLUS || t == tMINUS) {
179 if (!db_mult_expr(&rhs)) {
180 db_error("Syntax error\n");
181 /*NOTREACHED*/
182 }
183 if (t == tPLUS)
184 lhs += rhs;
185 else
186 lhs -= rhs;
187 t = db_read_token();
188 }
189 db_unread_token(t);
190 *valuep = lhs;
191 return (TRUE);
192 }
193
194 static boolean_t
195 db_shift_expr(valuep)
196 db_expr_t *valuep;
197 {
198 db_expr_t lhs, rhs;
199 int t;
200
201 if (!db_add_expr(&lhs))
202 return (FALSE);
203
204 t = db_read_token();
205 while (t == tSHIFT_L || t == tSHIFT_R) {
206 if (!db_add_expr(&rhs)) {
207 db_error("Syntax error\n");
208 /*NOTREACHED*/
209 }
210 if (rhs < 0) {
211 db_error("Negative shift amount\n");
212 /*NOTREACHED*/
213 }
214 if (t == tSHIFT_L)
215 lhs <<= rhs;
216 else {
217 /* Shift right is unsigned */
218 lhs = (unsigned) lhs >> rhs;
219 }
220 t = db_read_token();
221 }
222 db_unread_token(t);
223 *valuep = lhs;
224 return (TRUE);
225 }
226
227 int
228 db_expression(valuep)
229 db_expr_t *valuep;
230 {
231 return (db_shift_expr(valuep));
232 }
233
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