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 * $FreeBSD: src/sys/ddb/db_expr.c,v 1.13 1999/08/28 00:41:07 peter Exp $
27 * $DragonFly: src/sys/ddb/db_expr.c,v 1.4 2005/12/23 21:35:44 swildner Exp $
28 */
29
30 /*
31 * Author: David B. Golub, Carnegie Mellon University
32 * Date: 7/90
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(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
101 static boolean_t
102 db_unary(db_expr_t *valuep)
103 {
104 int t;
105
106 t = db_read_token();
107 if (t == tMINUS) {
108 if (!db_unary(valuep)) {
109 db_error("Syntax error\n");
110 /*NOTREACHED*/
111 }
112 *valuep = -*valuep;
113 return (TRUE);
114 }
115 if (t == tSTAR) {
116 /* indirection */
117 if (!db_unary(valuep)) {
118 db_error("Syntax error\n");
119 /*NOTREACHED*/
120 }
121 *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE);
122 return (TRUE);
123 }
124 db_unread_token(t);
125 return (db_term(valuep));
126 }
127
128 static boolean_t
129 db_mult_expr(db_expr_t *valuep)
130 {
131 db_expr_t lhs, rhs;
132 int t;
133
134 *valuep = 0; /* silence gcc */
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
166 static boolean_t
167 db_add_expr(db_expr_t *valuep)
168 {
169 db_expr_t lhs, rhs;
170 int t;
171
172 *valuep = 0; /* silence gcc */
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(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
226 int
227 db_expression(db_expr_t *valuep)
228 {
229 return (db_shift_expr(valuep));
230 }
Cache object: 467306568a9f1a4b9d3c4e60943e1f40
|