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         if (!db_unary(&lhs))
 135             return (FALSE);
 136
 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*/
 142             }
 143             if (t == tSTAR)
 144                 lhs *= rhs;
 145             else {
 146                 if (rhs == 0) {
 147                     db_error("Divide by 0\n");
 148                     /*NOTREACHED*/
 149                 }
 150                 if (t == tSLASH)
 151                     lhs /= rhs;
 152                 else if (t == tPCT)
 153                     lhs %= rhs;
 154                 else
 155                     lhs = ((lhs+rhs-1)/rhs)*rhs;
 156             }
 157             t = db_read_token();
 158         }
 159         db_unread_token(t);
 160         *valuep = lhs;
 161         return (TRUE);
 162 }
 163
 164 static boolean_t
 165 db_add_expr(db_expr_t *valuep)
 166 {
 167         db_expr_t       lhs, rhs;
 168         int             t;
 169
 170         if (!db_mult_expr(&lhs))
 171             return (FALSE);
 172
 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*/
 178             }
 179             if (t == tPLUS)
 180                 lhs += rhs;
 181             else
 182                 lhs -= rhs;
 183             t = db_read_token();
 184         }
 185         db_unread_token(t);
 186         *valuep = lhs;
 187         return (TRUE);
 188 }
 189
 190 static boolean_t
 191 db_shift_expr(db_expr_t *valuep)
 192 {
 193         db_expr_t       lhs, rhs;
 194         int             t;
 195
 196         if (!db_add_expr(&lhs))
 197             return (FALSE);
 198
 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*/
 204             }
 205             if (rhs < 0) {
 206                 db_error("Negative shift amount\n");
 207                 /*NOTREACHED*/
 208             }
 209             if (t == tSHIFT_L)
 210                 lhs <<= rhs;
 211             else {
 212                 /* Shift right is unsigned */
 213                 lhs = (unsigned) lhs >> rhs;
 214             }
 215             t = db_read_token();
 216         }
 217         db_unread_token(t);
 218         *valuep = lhs;
 219         return (TRUE);
 220 }
 221
 222 int
 223 db_expression(db_expr_t *valuep)
 224 {
 225         return (db_shift_expr(valuep));
 226 }