HAMMER Utilities: Mirroring and pseudo-fs directives
[dragonfly.git] / sys / ddb / db_expr.c
blob11a793a06e28f24e6791569968233bb7118ab668
1 /*
2 * Mach Operating System
3 * Copyright (c) 1991,1990 Carnegie Mellon University
4 * All Rights Reserved.
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.
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.
16 * Carnegie Mellon requests users of this software to return to
18 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
19 * School of Computer Science
20 * Carnegie Mellon University
21 * Pittsburgh PA 15213-3890
23 * any improvements or extensions that they make and grant Carnegie the
24 * rights to redistribute these changes.
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 $
31 * Author: David B. Golub, Carnegie Mellon University
32 * Date: 7/90
34 #include <sys/param.h>
36 #include <ddb/ddb.h>
37 #include <ddb/db_lex.h>
38 #include <ddb/db_access.h>
39 #include <ddb/db_command.h>
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);
47 static boolean_t
48 db_term(db_expr_t *valuep)
50 int t;
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*/
58 return (TRUE);
60 if (t == tNUMBER) {
61 *valuep = (db_expr_t)db_tok_number;
62 return (TRUE);
64 if (t == tDOT) {
65 *valuep = (db_expr_t)db_dot;
66 return (TRUE);
68 if (t == tDOTDOT) {
69 *valuep = (db_expr_t)db_prev;
70 return (TRUE);
72 if (t == tPLUS) {
73 *valuep = (db_expr_t) db_next;
74 return (TRUE);
76 if (t == tDITTO) {
77 *valuep = (db_expr_t)db_last_addr;
78 return (TRUE);
80 if (t == tDOLLAR) {
81 if (!db_get_variable(valuep))
82 return (FALSE);
83 return (TRUE);
85 if (t == tLPAREN) {
86 if (!db_expression(valuep)) {
87 db_error("Syntax error\n");
88 /*NOTREACHED*/
90 t = db_read_token();
91 if (t != tRPAREN) {
92 db_error("Syntax error\n");
93 /*NOTREACHED*/
95 return (TRUE);
97 db_unread_token(t);
98 return (FALSE);
101 static boolean_t
102 db_unary(db_expr_t *valuep)
104 int t;
106 t = db_read_token();
107 if (t == tMINUS) {
108 if (!db_unary(valuep)) {
109 db_error("Syntax error\n");
110 /*NOTREACHED*/
112 *valuep = -*valuep;
113 return (TRUE);
115 if (t == tSTAR) {
116 /* indirection */
117 if (!db_unary(valuep)) {
118 db_error("Syntax error\n");
119 /*NOTREACHED*/
121 *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE);
122 return (TRUE);
124 db_unread_token(t);
125 return (db_term(valuep));
128 static boolean_t
129 db_mult_expr(db_expr_t *valuep)
131 db_expr_t lhs, rhs;
132 int t;
134 if (!db_unary(&lhs))
135 return (FALSE);
137 t = db_read_token();
138 while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) {
139 if (!db_term(&rhs)) {
140 db_error("Syntax error\n");
141 /*NOTREACHED*/
143 if (t == tSTAR)
144 lhs *= rhs;
145 else {
146 if (rhs == 0) {
147 db_error("Divide by 0\n");
148 /*NOTREACHED*/
150 if (t == tSLASH)
151 lhs /= rhs;
152 else if (t == tPCT)
153 lhs %= rhs;
154 else
155 lhs = ((lhs+rhs-1)/rhs)*rhs;
157 t = db_read_token();
159 db_unread_token(t);
160 *valuep = lhs;
161 return (TRUE);
164 static boolean_t
165 db_add_expr(db_expr_t *valuep)
167 db_expr_t lhs, rhs;
168 int t;
170 if (!db_mult_expr(&lhs))
171 return (FALSE);
173 t = db_read_token();
174 while (t == tPLUS || t == tMINUS) {
175 if (!db_mult_expr(&rhs)) {
176 db_error("Syntax error\n");
177 /*NOTREACHED*/
179 if (t == tPLUS)
180 lhs += rhs;
181 else
182 lhs -= rhs;
183 t = db_read_token();
185 db_unread_token(t);
186 *valuep = lhs;
187 return (TRUE);
190 static boolean_t
191 db_shift_expr(db_expr_t *valuep)
193 db_expr_t lhs, rhs;
194 int t;
196 if (!db_add_expr(&lhs))
197 return (FALSE);
199 t = db_read_token();
200 while (t == tSHIFT_L || t == tSHIFT_R) {
201 if (!db_add_expr(&rhs)) {
202 db_error("Syntax error\n");
203 /*NOTREACHED*/
205 if (rhs < 0) {
206 db_error("Negative shift amount\n");
207 /*NOTREACHED*/
209 if (t == tSHIFT_L)
210 lhs <<= rhs;
211 else {
212 /* Shift right is unsigned */
213 lhs = (unsigned) lhs >> rhs;
215 t = db_read_token();
217 db_unread_token(t);
218 *valuep = lhs;
219 return (TRUE);
223 db_expression(db_expr_t *valuep)
225 return (db_shift_expr(valuep));