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 */
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
40 static boolean_t db_add_expr (db_expr_t *valuep);
41 static boolean_t db_mult_expr (db_expr_t *valuep);
42 static boolean_t db_shift_expr (db_expr_t *valuep);
43 static boolean_t db_term (db_expr_t *valuep);
44 static boolean_t db_unary (db_expr_t *valuep);
45
46 static boolean_t
db_term(db_expr_t * valuep)47 db_term(db_expr_t *valuep)
48 {
49 int t;
50
51 t = db_read_token();
52 if (t == tIDENT) {
53 if (!db_value_of_name(db_tok_string, valuep)) {
54 db_error("Symbol not found\n");
55 /*NOTREACHED*/
56 }
57 return (TRUE);
58 }
59 if (t == tNUMBER) {
60 *valuep = (db_expr_t)db_tok_number;
61 return (TRUE);
62 }
63 if (t == tDOT) {
64 *valuep = (db_expr_t)db_dot;
65 return (TRUE);
66 }
67 if (t == tDOTDOT) {
68 *valuep = (db_expr_t)db_prev;
69 return (TRUE);
70 }
71 if (t == tPLUS) {
72 *valuep = (db_expr_t) db_next;
73 return (TRUE);
74 }
75 if (t == tDITTO) {
76 *valuep = (db_expr_t)db_last_addr;
77 return (TRUE);
78 }
79 if (t == tDOLLAR) {
80 if (!db_get_variable(valuep))
81 return (FALSE);
82 return (TRUE);
83 }
84 if (t == tLPAREN) {
85 if (!db_expression(valuep)) {
86 db_error("Syntax error\n");
87 /*NOTREACHED*/
88 }
89 t = db_read_token();
90 if (t != tRPAREN) {
91 db_error("Syntax error\n");
92 /*NOTREACHED*/
93 }
94 return (TRUE);
95 }
96 db_unread_token(t);
97 return (FALSE);
98 }
99
100 static boolean_t
db_unary(db_expr_t * valuep)101 db_unary(db_expr_t *valuep)
102 {
103 int t;
104
105 t = db_read_token();
106 if (t == tMINUS) {
107 if (!db_unary(valuep)) {
108 db_error("Syntax error\n");
109 /*NOTREACHED*/
110 }
111 *valuep = -*valuep;
112 return (TRUE);
113 }
114 if (t == tSTAR) {
115 /* indirection */
116 if (!db_unary(valuep)) {
117 db_error("Syntax error\n");
118 /*NOTREACHED*/
119 }
120 *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE);
121 return (TRUE);
122 }
123 db_unread_token(t);
124 return (db_term(valuep));
125 }
126
127 static boolean_t
db_mult_expr(db_expr_t * valuep)128 db_mult_expr(db_expr_t *valuep)
129 {
130 db_expr_t lhs, rhs;
131 int t;
132
133 *valuep = 0; /* silence gcc */
134
135 if (!db_unary(&lhs))
136 return (FALSE);
137
138 t = db_read_token();
139 while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) {
140 if (!db_term(&rhs)) {
141 db_error("Syntax error\n");
142 /*NOTREACHED*/
143 }
144 if (t == tSTAR)
145 lhs *= rhs;
146 else {
147 if (rhs == 0) {
148 db_error("Divide by 0\n");
149 /*NOTREACHED*/
150 }
151 if (t == tSLASH)
152 lhs /= rhs;
153 else if (t == tPCT)
154 lhs %= rhs;
155 else
156 lhs = roundup(lhs, rhs);
157 }
158 t = db_read_token();
159 }
160 db_unread_token(t);
161 *valuep = lhs;
162 return (TRUE);
163 }
164
165 static boolean_t
db_add_expr(db_expr_t * valuep)166 db_add_expr(db_expr_t *valuep)
167 {
168 db_expr_t lhs, rhs;
169 int t;
170
171 *valuep = 0; /* silence gcc */
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
193 static boolean_t
db_shift_expr(db_expr_t * valuep)194 db_shift_expr(db_expr_t *valuep)
195 {
196 db_expr_t lhs, rhs;
197 int t;
198
199 if (!db_add_expr(&lhs))
200 return (FALSE);
201
202 t = db_read_token();
203 while (t == tSHIFT_L || t == tSHIFT_R) {
204 if (!db_add_expr(&rhs)) {
205 db_error("Syntax error\n");
206 /*NOTREACHED*/
207 }
208 if (rhs < 0) {
209 db_error("Negative shift amount\n");
210 /*NOTREACHED*/
211 }
212 if (t == tSHIFT_L)
213 lhs <<= rhs;
214 else {
215 /* Shift right is unsigned */
216 lhs = (unsigned) lhs >> rhs;
217 }
218 t = db_read_token();
219 }
220 db_unread_token(t);
221 *valuep = lhs;
222 return (TRUE);
223 }
224
225 int
db_expression(db_expr_t * valuep)226 db_expression(db_expr_t *valuep)
227 {
228 return (db_shift_expr(valuep));
229 }
230